Every-day Science: Volume 7. The Conquest of Time and Space
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Title: Every-day Science: Volume 7. The Conquest of Time and Space
Author: Henry Smith Williams
Edward Huntington Williams
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*** START OF THE PROJECT GUTENBERG EBOOK EVERY-DAY SCIENCE: VOLUME 7. THE CONQUEST OF TIME AND SPACE ***
[Illustration: THE WRIGHT AEROPLANE IN FRANCE IN 1908.
It will be seen that there are two passengers on the aeroplane, one
being Mr. Wilbur Wright, the other a pupil.]
EVERY-DAY SCIENCE
BY
HENRY SMITH WILLIAMS, M.D., LL.D.
ASSISTED BY
EDWARD H. WILLIAMS, M.D.
VOLUME VII.
THE CONQUEST OF TIME AND SPACE
ILLUSTRATED
[Illustration]
NEW YORK AND LONDON
THE GOODHUE COMPANY
PUBLISHERS MDCCCCX
Copyright, 1910, by THE GOODHUE CO.
_All rights reserved_
CONTENTS
CHAPTER I
THE CONQUEST OF THE ZONES
Geographical knowledge of the ancient Egyptians, p. 5--The
mariner's compass, p. 7--Reference to the thirty-two points
of the compass by Chaucer, p. 9--Halley's observations on
the changes in the direction of the compass in a century,
p. 10--Deviation of the compass, p. 11--The voyage of the
_Carnegie_, the non-magnetic ship, p. 12--The "dip of the needle"
first observed by Robert Norman, p. 13--The modern compass
invented by Lord Kelvin, p. 14--Sailing by dead reckoning, p.
14--The invention of the "log," p. 15--The modern log, p. 17--The
development of the sextant, p. 18--The astrolabe, p. 19--The
quadrant invented by Hadley, p. 20--The perfected sextant, p.
21--Perfecting the chronometer, p. 23--The timepieces invented
by the British carpenter, John Harrison, p. 25--The prize won by
Harrison, p. 27--Finding time without a chronometer, p. 28--The
_Nautical Almanac_, p. 30--Ascertaining the ship's longitude, p.
31--Difficulties of "taking the sun" at noon, p. 33--Measuring
a degree of latitude, p. 34--The observations of Robert Norman,
p. 35--The function of the _Nautical Almanac_, p. 37--Soundings
and charts, p. 41--Mercator's projection, p. 44--The lure of the
unknown, p. 45--The quest of the Pole, p. 47--Commander Peary's
achievement, p. 49--How observations are made in arctic regions,
p. 50--Making observations at the Pole, p. 52--Difficulties as to
direction at the Pole, p. 54.
CHAPTER II
THE HIGHWAY OF THE WATERS
Use of sails in ancient times, p. 56--Ships with many banks
of oars, p. 57--Mediæval ships, p. 59--Modern sailing ships,
p. 60--The sailing record of _The Sovereign of the Seas_,
p. 60--Early attempts to invent a steamboat, p. 63--Robert
Fulton's _Clermont_, p. 64--The steamboat of Blasco de Gary,
p. 66--The _Charlotte Dundas_, p. 67--The steamboat invented
by Col. John Stevens, p. 68--Fulton designs the _Clermont_,
p. 71--The historic trip of the _Clermont_ up the Hudson, p.
71--Sea-going steamships, p. 73--Ships built of iron and steel,
p. 74--The _Great Eastern_, p. 76--Principal dimensions of the
_Great Eastern_, p. 78--Twin-screw vessels, p. 80--The triumph
of the turbine, p. 81--The _Lusitania_ and _Mauretania_, p.
82--Submarine signalling, p. 83--The rescue of the _Republic_,
p. 84--How the submarine signalling device works, p. 86--The
_Olympic_ and _Titanic_, p. 90--Liquid fuel, p. 90--Advantages
and disadvantages of liquid fuel, p. 91.
CHAPTER III
SUBMARINE VESSELS
Slow development of submarine navigation, p. 93--The first
submarine, p. 94--Description of David Bushnell's boat, p.
94--Attempts to sink a war vessel during the American Revolution,
p. 97--Robert Fulton's experiments, p. 98--The attack on the
_Argus_ by Fulton's submarine, p. 100--The attack upon the
_Ramilles_ in 1813, p. 102--A successful diving boat, p. 103--The
sinking of the _Housatonic_, p. 104--Recent submarines and
submersibles, p. 105--The _Holland_, p. 106--The Lake type of
boat, p. 108--Problems to be overcome in submarine navigation, p.
109--Present status of submarine boats, p. 111--The problem of
seeing without being seen, p. 113--The experimental attacks upon
the cruiser _Yankee_ in 1908, p. 115--The possibility of using
aeroplanes for detecting the presence of submarines, p. 117.
CHAPTER IV
THE STEAM LOCOMOTIVE
The earliest railroad, p. 119--The substitution of flanged
wheels for flanged rails, p. 120--The locomotive of Richard
Trevithick, p. 121--The cable road of Chapman, p. 123--Stephenson
solves the problem, p. 124--Versatility of Stephenson, p.
125--His early locomotives, p. 126--Stephenson's locomotive of
1825, p. 127--The first passenger coach, p. 128--The Liverpool
and Manchester Railway projected, p. 129--Conditions named
for testing the competing locomotives, p. 130--The _Rocket_
and other contestants, p. 132--Description of the _Rocket_,
p. 133--Improvements on the construction of the _Rocket_, p.
134--Improvements in locomotives in recent years, p. 135--The
compound locomotive, p. 137--Advantages of compound locomotives,
p. 138--The Westinghouse air brake, p. 141--The "straight air
brake," p. 143--The automatic air brake, p. 144--The high-speed
air brake, p. 146--Automatic couplings, p. 147--Principle of the
Janney coupling, p. 149--A comparison--the old and the new, p.
150.
CHAPTER V
FROM CART TO AUTOMOBILE
When were carts first used? p. 152--The development of the
bicycle, p. 154--The pneumatic tire introduced, p. 155--The
coming of the automobile, p. 156--The gas engine of Dr. Otto,
p. 157--Cugnot's automobile, p. 158--The automobile of William
Murdoch, 1785, p. 158--Opposition in England to the introduction
of automobiles, p. 159--An extraordinary piece of legislation,
p. 161--Scientific aspects of automobile racing, p. 164--Some
records made at Ormonde, p. 165--Records made by Oldfield
in 1910, p. 166--Comparative speeds of various vehicles and
animals, p. 167--Speed of birds in flight, p. 168--A miraculous
transformation of energy, p. 170--Electrical timing device for
measuring automobile speeds, p. 171.
CHAPTER VI
THE DEVELOPMENT OF ELECTRIC RAILWAYS
New York the first city to have a street railway, p. 175--Cable
systems, p. 177--Early self-sustained systems, p. 178--The
electro-magnetic locomotive of Moses G. Farmer, p. 179--The
efforts of Professor Page to produce a storage battery car,
p. 180--The experiments of Siemens and Halske with electric
motors, p. 181--The Edison electric locomotive, p. 182--Third
rails and trolleys, p. 184--The inventions of Daft and Van
Depoele, p. 185--The work of Frank J. Sprague in developing
electric railways, p. 186--How the word "trolley" was coined, p.
187--Storage battery systems, p. 188--The Edison storage battery
car of 1910, p. 189--Monorail systems, p. 191--Electric aerial
monorail systems, p. 193.
CHAPTER VII
THE GYROCAR
Mr. Louis Brennan's car exhibited before the Royal Society in
London, p. 195--How the gyroscope is installed on this car, p.
196--Gyroscopic action explained, p. 197--Why does the spinning
wheel exert gyroscopic power? p. 199--Mr. Brennan's model car,
p. 200--The "wabble" of the gyroscope explained, p. 202--How
the Brennan gyroscopes work, p. 203--Technical explanation of
the gyroscope, p. 204--The evolution of an idea, p. 213--Sir
Henry Bessemer's experiment, p. 214--What may be expected of the
gyrocar, p. 215.
CHAPTER VIII
THE GYROSCOPE AND OCEAN TRAVEL
Bessemer's costly experiment, p. 217--Dr. Schlick's successful
experiment, p. 219--The action of Dr. Schlick's invention
explained, p. 220--Did gyroscopic action wreck the _Viper_? p.
222--Theoretical dangers of the gyroscope, p. 223--Probable use
of the gyroscope on battleships, p. 225.
CHAPTER IX
NAVIGATING THE AIR
Some mediæval traditions about airships, p. 266--The flying
machines devised by Leonardo da Vinci, p. 277--The flying
machine of Besnier, p. 228--The discovery of hydrogen gas and
its effect upon aeronautics, p. 230--The balloon invented, p.
231--The first successful balloon ascension, p. 232--Rozier, the
first man to make an ascent in a balloon, p. 235--Blanchard's
attempt to produce a dirigible balloon, p. 238--Hot-air
balloons and hydrogen-gas balloons, p. 240--Rozier, the first
victim of ballooning, p. 241--Progress in mechanical flight,
p. 244--Cocking's parachute, p. 245--Henson's studies of the
lifting power of plane surfaces, p. 246--The flying machine
of Captain Le Bris, p. 248--Giffard "the Fulton of aerial
navigation," p. 251--The flights of the _Giant_, p. 252--The
record flight of John Wise in 1859, p. 256--Early war balloons
and dirigible balloons, p. 257--The use of balloons during the
Franco-Prussian war, p. 258--The dirigible balloon achieved, p.
262--The dirigible balloon of Dupuy de Lome, p. 263--The aluminum
balloon of Herr Schwartz, p. 264--The dirigible balloons of Count
Zeppelin, p. 266--Early experiments of Santos-Dumont, p. 267.
CHAPTER X
THE TRIUMPH OF THE AEROPLANE
Balloon versus aeroplane, p. 272--The kite as a flying machine,
p. 273--How the air sustains a heavier-than-air mechanism, p.
274--Langley's early experiments, p. 275--Experiments in soaring,
p. 277--Lilienthal's imitation of the soaring bird, p. 279--Sir
Hiram Maxim's flying machine, p. 283--Langley's successful
aerodrome, p. 284--The failure of Langley's larger aerodrome,
p. 287--Wilbur and Orville Wright accomplish the impossible, p.
288--The first public demonstration by the Wright brothers, p.
290--The Wright aeroplane described, p. 291--A host of imitators,
p. 292--Mr. Henry Farman's successful flights, p. 293--Public
demonstrations by the Wright brothers in America and France, p.
293--The English Channel crossed by Blériot, p. 294--Orville
Wright fulfils the Government tests, p. 295--Spectacular
cross-country flights, p. 296--The Wright brothers the true
pioneers, p. 300.
ILLUSTRATIONS
THE WRIGHT AEROPLANE IN FRANCE IN 1908 _Frontispiece_
_Facing page_
"TAKING THE SUN" WITH THE SEXTANT 22
THE OLD AND THE NEW--A CONTRAST 60
MARINE ENGINES AND AN EARLY TYPE OF STEAMBOAT 64
THE STEAMSHIPS "CHARLOTTE DUNDAS" AND "CLERMONT" 68
THE "CLERMONT" 72
ROBERT FULTON 98
THE AMERICAN SUBMARINE BOAT "CUTTLEFISH" IN DRY DOCK AT
THE BROOKLYN NAVY YARD 108
A FLEET OF BRITISH SUBMARINES MANŒUVERING AT THE SURFACE 116
GEORGE STEPHENSON 124
A CENTURY'S PROGRESS IN LOCOMOTIVE BUILDING 128
CUGNOT'S TRACTION ENGINE AND THE "NOVELTY" LOCOMOTIVE 132
THE FAMOUS LOCOMOTIVES "ROCKET" AND "SANS-PAREIL" 134
THE DEVELOPMENT OF THE LOCOMOTIVE 150
THE HOBBY-HORSE OF 1820 CONTRASTED WITH THE MOTOR CYCLE
OF TO-DAY 154
THE EVOLUTION OF THE BICYCLE 156
THE EXTREMES OF AUTOMOBILE DEVELOPMENT 158
AN ENGLISH STEAM COACH OF 1827 AND A NEW YORK TAXICAB
OF 1909 162
A RACING AUTOMOBILE 166
RETROSPECT AND PROSPECT IN TRANSPORTATION--THE DE WITT
CLINTON TRAIN AND THE GYROCAR 200
TWO VIEWS OF MR. LOUIS BRENNAN'S MONORAIL GYROCAR 216
AN INTERNATIONAL BALLOON RACE 242
TWO FAMOUS FRENCH WAR BALLOONS 264
THE ZEPPELIN DIRIGIBLE BALLOON 266
AN ENGLISH DIRIGIBLE BALLOON 268
ENGLISH AND AMERICAN DIRIGIBLE WAR BALLOONS AND A
WRIGHT AEROPLANE 270
THE AEROPLANE OF M. SANTOS-DUMONT 272
LEARNING HOW TO FLY 278
FLYING MACHINES OF THE MONOPLANE TYPE 284
THE WRIGHT AEROPLANE 288
MR. WILBUR WRIGHT PREPARING TO ASCEND IN HIS AEROPLANE
WITH HIS PUPIL M. CASSANDIER 292
THE FARMAN AEROPLANE 294
THE MONOPLANES OF BLÉRIOT AND LATHAM 296
A BRITISH AEROPLANE 298
MR. WILBUR WRIGHT FLYING OVER NEW YORK HARBOR,
OCTOBER 4, 1909 300
THE CONQUEST OF TIME AND SPACE
INTRODUCTION
The preceding volume dealt with the general principles of application
and transformation of the powers of Nature through which the world's
work is carried on. In the present volume we are chiefly concerned
with man's application of the same principles in his efforts to set at
defiance, so far as may be, the limitations of time and space.
Something has already been said as to the contrast between the
material civilization of to-day and that of the generations prior to
the nineteenth century. The transformation in methods of agriculture
and manufacture has been referred to somewhat in detail. Now we
have to do with contrasts that are perhaps even more vivid, since
they concern conditions that come within the daily observation of
everyone. Steamships, locomotives, electric cars, and automobiles,
are such commonplaces of every-day life that it is difficult to
conceive a world in which they have no part. Yet everyone is aware
that all these mechanisms are inventions of the nineteenth century.
Meantime the aeroplane, which bids fair to rival those other means
of transportation in the near future, is a creation of the twentieth
century.
In order to visualize the contrast between the practical civilization
of to-day and that of our grandparents, it suffices to recall that the
first steam locomotive that carried passengers over a railway was put
in operation in the year 1829; and that the first ship propelled by
steam power alone did not cross the ocean until 1838. Not until well
towards the middle of the nineteenth century, then, were the conditions
of transportation altered materially from what they had been since the
very dawn of civilization,--conditions under which one hundred miles
constituted about the maximum extent of a hard day's land journey.
The elaboration of railway and steamship lines through which nearly
all portions of the habitable globe have been made accessible, has
constituted one of the most remarkable examples of economic development
that man has ever achieved. It requires but the slightest use of the
imagination to realize with some measure of vividness the extent to
which the entire structure of present-day civilization is based upon
this elaboration of means of transportation. To point but a single
illustration, the entire central and western portion of the United
States must have remained a wilderness for decades or centuries had not
the steam locomotive made communication easy between these regions and
the seaboard.
Contrariwise no such development of city life as that which we see
throughout Christendom would have been possible but for the increased
facilities, due primarily to locomotives and steamships, for bringing
all essential food-stuffs from distant regions.
What this all means when applied on a larger scale may be suggested
by the reflection that the entire character of the occupation of the
average resident of England has been changed within a century. A
century ago England was a self-supporting nation, in the sense that
it produced its own food-stuffs. To-day the population of England as
a whole is dependent upon food shipped to it from across the oceans.
Obviously such a transformation could never have been effected had
not the application of steam revolutionized the entire character of
transportation.
Far-reaching as are the economic aspects of the problem of
transportation, this extraordinary revolution, the effects of which
are visible on every side, has been brought about by the application
of only a few types of mechanisms. The steam engine, the dynamo, and
the gas engine are substantially responsible for the entire development
in question. In the succeeding pages, which deal with the development
of steamships, locomotives, automobiles, and flying machines, we have
to do with the application of principles with which our previous
studies have made us familiar; and in particular with the mechanisms
that have engaged our attention in the preceding volume. Yet the
application of these principles and the utilization of these mechanisms
gave full opportunity for the exercise of inventive ingenuity, and
the story of the development of steamships, locomotives, electric
vehicles, automobiles, gyro cars, and flying machines, will be found
to have elements of interest commensurate with the importance of these
mechanisms themselves. Before we take up these stories in detail,
however, we shall briefly review the story of geographical discovery
and exploration in its scientific aspects.
I
THE CONQUEST OF THE ZONES
The contrast between modern and ancient times is strikingly suggested
by reflection on the limited range of geographical knowledge of those
Oriental and Classical nations who dominated the scene at that remote
period which we are accustomed to characterize as the dawn of history.
The Egyptians, peopling the narrow valley of the Nile, scarcely had
direct dealings with any people more remote than the Babylonians
and Assyrians occupying the valley of the Euphrates. Babylonians
and Assyrians in turn were in touch with no Eastern civilization
more remote than that of Persia and India, and knew nothing of any
Western world beyond the borders of Greece. Greeks and Romans, when
in succession they came to dominate the world stage,--developing a
civilization which even as viewed from our modern vantage-ground seems
marvelous,--were still confined to narrow strips of territory about the
shores of the Mediterranean, and had but the vaguest notions as to any
other regions of the earth.
In the later classical period, to be sure, the globe was subjected,
as we have seen, to wonderful measurements by Eratosthenes and by
Posidonius, and the fact that man's abiding place is a great ball
utterly different from the world as conceived by the Oriental mind,
was definitely grasped and became more or less a matter of common
knowledge. It was even conceived that there might be a second habitable
zone on the opposite side of the equator from the region in which
the Greeks and Romans found themselves, but as to just what this
hypothetical region might be like, and as to what manner of beings
might people it, even the most daring speculator made no attempt
to decide. The more general view, indeed, precluded all thought of
habitable regions lying beyond the confines of the Mediterranean
civilization; conceiving rather that the world beyond was a mere waste
of waters.
Doubtless the imaginative mind of the period must have chafed under
these restrictions of geographical knowledge; and now and again a more
daring navigator must have pressed out beyond the limits of safety,
into the Unknown, never to return. Once at least, even in the old
Egyptian days, a band of navigators surpassing in daring all their
predecessors, and their successors of the ensuing centuries, made bold
to continue their explorations along the coast of Africa till they had
passed to a region where--as Herodotus relates with wonder--the sun
appeared "on their right hand," ultimately passing about the southern
extremity of the African continent and in due course completing the
circumnavigation, returning with wonder tales to excite the envy,
perhaps, but not the emulation of their fellows.
Then in due course some Phœnician or Greek navigators coasted along the
northern shores beyond the "Pillars of Hercules" and discovered at the
very confines of the world what we now term the British Isles. But this
was the full extent of exploration throughout antiquity; and the spread
of civilization about the borders of the known world was a slow and
haphazard procedure during all those centuries that mark the Classical
and Byzantine periods.
THE MARINER'S COMPASS
The change came with that revival of scientific learning which was
to usher in the new era that we speak of as modern times. And here
as always it was a practical mechanism that gave the stimulus to new
endeavor. In this particular case the implement in question was the
mariner's compass, which consists, in its essentials, as everyone is
aware, of a magnetized needle floated or suspended in such a way that
it is made under the influence of terrestrial magnetism to point to the
north and south.
The mysterious property whereby the magnetized needle obeys this
inscrutable impulse is, in the last analysis, inexplicable even to
the science of our day. But the facts, in their cruder relations,
had been familiar from time immemorial to a nation whose habitat lay
beyond the ken of the classical world--namely, the Chinese. It seems
to be fairly established that navigators of that nation had used the
magnetized needle, so arranged as to constitute a crude compass, from
a period possibly antedating the Christian Era. To Western nations,
however, the properties of the magnetized needle seem to have
been quite unknown--at least its possibilities of practical aid to
the navigator were utterly unsuspected--until well into the Middle
Ages. There is every reason to believe--though absolute proof is
lacking--that a knowledge of the compass came to the Western world from
the Far East through the medium of the Arabs. The exact channel of
this communication will perhaps always remain unknown. Nor have we any
clear knowledge as to the exact time when the all-important information
was transmitted. We only know that manuscripts of the twelfth century
mentioned the magnetic needle as an implement familiar to navigators,
and from this time forward, we may feel sure, the new possibilities of
exploration made possible by the compass must have suggested themselves
to some at least of the more imaginative minds of each generation.
Indeed there were explorers in each generation who pushed out a little
into the unknown, as the discovery of various groups of Islands in
the Atlantic shows, although the efforts of these pioneers have been
eclipsed by the spectacular feat of Columbus.
The exact steps by which the crude compass of the Orientals was
developed into the more elaborate and delicate instrument familiar to
Western navigators cannot be traced by the modern historian. It is
known that sundry experiments were made as to the best form of needle,
and in particular as to the best way of adjusting it on approximately
frictionless bearings. But a high degree of perfection in this regard
had been attained before the modern period; and the compass had
been further perfected by attaching the needle to a circumferential
card on which the "points of the compass," thirty-two in number,
were permanently marked. At all events the compass card had been so
divided before the close of the fourteenth century, as is proved by
a chance reference by Chaucer. The utility of the instrument thus
perfected--indeed its entire indispensableness--was doubtless by this
time clearly recognized by all navigators; and one risks nothing in
suggesting that without the compass no such hazardous voyage into the
unknown as that of Columbus would ever have been attempted.
No doubt the earliest observers of the needle believed that it pointed
directly to the North. If such were indeed the fact the entire science
of navigation would be vastly simpler than it is. But it required no
very acute powers of observation to discover that the magnetized needle
does not in reality point directly towards the earth's poles. There
are indeed places on the earth where it does so point, but in general
it is observed to deviate by a few degrees from the exact line of the
meridian. Such deviation is technically known as magnetic declination.
That this declination is not the same for all places was discovered by
Columbus in the course of his first transatlantic voyage.
A century or so later, the accumulated records made it clear that
declination is not a fixed quantity even at any given place. An
Englishman, Stephen Burrows, is credited with making the discovery
that the needle thus shifts its direction slightly with the lapse
of time, and the matter was more clearly determined a little later
by Gillebrand, Professor of Geometry at Graham College. Dr. Halley,
the celebrated astronomer--whose achievements have been recalled to
succeeding generations by the periodical return of the comet that bears
his name--gave the matter attention, and in a paper before the Royal
Society in 1692 he pointed out that the direction of the needle at
London had changed in a little over a century (between 1580 and 1692)
from 11 degrees 15 minutes East to 6 degrees West, or more than 17
degrees.
Halley conclusively showed that similar variations occurred at all
other places where records had been kept. He had already demonstrated,
a few years earlier, that the deviations of the compass noted at sea
are not due to the varying attractions of neighboring bodies of land,
but to some influence having to do with the problem of terrestrial
magnetism in its larger aspects. Halley advocated the doctrine, which
had first been put forward by William Gilbert, that the earth itself
is a gigantic magnet, and that the action of the compass is dependent
upon this terrestrial source and not, as many navigators believed, on
the influence of a magnetic star, or on localized deposits of lodestone
somewhere in the unknown regions of the North.
Further observations of the records presently made it clear that there
are also annual and even daily variations of the compass of slight
degree. The fact of diurnal variations was first discovered by Mr.
Graham about the year 1719. More than half a century later it was
observed by an astronomer named Wales, who was accompanying Captain
Cook on his famous voyage round the world (1772-74), that there is yet
another fluctuation of the compass due to the influence of the ship
on which it is placed. Considerable quantities of iron were of course
used in the construction of wooden ships, and it was made clear that
the ship itself comes under the influence of the earth's magnetism and
exerts in turn an appreciable influence on the compass. The fluctuation
due to this source is known as deviation, in contradistinction to the
larger fluctuation already referred to as declination.
Not only is the deviation due to the ship's influence a matter of
importance, but it was discovered by Captain Matthew Flinders, in the
course of his explorations along the coast of New Holland in the year
1801-02, that the influence of the ship over its compass varies with
the direction of the ship's prow.
Needless to say, the problem of the deviation of the compass due to the
influence of the ship is enormously complicated when the ship instead
of being constructed chiefly of wood is made of iron or steel. It then
becomes absolutely essential that the influence of vessels shall be
reckoned with and so far as possible compensated. Such compensation may
be effected by the adjustment of bodies of iron, as first suggested
by Barlow, or by the use of permanent magnets, as first attempted
by England's Astronomer Royal, Professor Airy. At the very best,
however, it is never possible totally to overcome the ship's perverting
influence, allowance for which must be made if an absolutely accurate
conclusion is to be drawn from the record presented by the compass.
Early in the twentieth century an American ship, christened the
_Carnegie_, in honor of the philanthropist who supplied funds for the
enterprise, was constructed for the express purpose of making accurate
charts of the lines of magnetic declination in various parts of the
globe. This ship differs from every other vessel of considerable size
ever hitherto constructed in that no magnetic material of any kind
was used in connection with its structure or equipment. For the most
part iron was substituted by copper or other non-magnetic metal.
Pins of locust-wood largely took the place of nails; and wherever it
was not feasible to do away with iron altogether it was used in the
form of non-magnetic manganese steel. The purpose of the _Carnegie_
is to provide accurate charts of magnetic declination for the use
of navigators in general. The value of observations made with this
non-magnetic ship will be clear when it is reflected that with an
ordinary ship the observer can never be absolutely certain as to what
precise share of the observed fluctuation of the compass is due at any
given moment to the ship's influence. In other words--using technical
terminology--he can never apportion with absolute accuracy the
influence of declination and of deviation. Yet it is highly important
that he should be able to do so, inasmuch as the declination of the
compass is an all-important element in reckoning the exact location of
the ship, and would be the same for every ship at that place, whereas
deviation denotes a purely local disturbance which would never be the
same for any two ships of different construction.
Not only does the magnetized needle thus tend to vary in the direction
of its horizontal action, but it also tends when suspended at the
middle to shift its vertical axis. In regions near the equator, indeed,
the magnetized needle maintains a horizontal position, but if carried
into northern or southern latitudes it progressively "dips," its
polar end sinking lower and lower. This dipping of the needle seems
to have been first observed by Robert Norman, an English nautical
instrument maker, about the year 1590. It was brought to the attention
of Gilbert and carefully tested by him in the course of his famous
pioneer experiments. Gilbert was led to predicate the existence of
magnetic poles, the exact location of which would be indicated by the
dipping needle, which, sinking lower and lower as northern latitudes
were attained, would ultimately at the magnetic pole itself assume a
vertical direction.
That this is a correct expression of the facts was determined in
the year 1831 by Sir James Ross, who in the course of his Arctic
explorations observed the vertical dip and so located the northern
magnetic pole at about 70 degrees 5 minutes north latitude and 96
degrees 43 minutes west longitude. It was thus proved that the magnetic
pole is situated a long distance--more than 1,200 miles--from the
geographical pole. The location of the south magnetic pole was most
accurately determined in 1909 by Lieutenant Shackleton's expedition at
about 73 degrees south latitude and 156 degrees east longitude. The two
magnetic poles are thus not directly opposite each other on the earth's
surface, and the magnetic axis of the earth does not coincide with the
geographical center of the globe itself.
From the standpoint of practical navigation the dip of the needle is
a matter of much less significance than its horizontal fluctuations.
Robert Norman himself attempted to overcome the dip by a balancing
apparatus applied to the needle; and the modern compass is suspended
in such a way that the propensity to dip does not interfere with
the lateral movements which supply the navigator with all important
information. The modern compass in question is the invention of
Lord Kelvin and was patented by him in 1876. It consists of a
number of small magnets arranged in parallel and held in position
by silk threads, each suspended, cobweb-like, from the circular
rim of aluminum. The weight--which in the aggregate is relatively
slight--being thus largely at the circumference, the instrument has a
maximum period of oscillation and hence a high degree of stability. Its
fluctuations due to the ship's influence are corrected by a carefully
adjusted disposition of metal balls and magnets.
SAILING BY DEAD RECKONING
While the compass gives indispensable information as to direction,
and is constantly under the eye of the pilot, it of course can give
no direct information as to the distance traversed by the ship, and
hence does not by itself suffice to tell the navigator his whereabouts.
In the early days there was indeed an expectation that the observed
declination of the compass would reveal to the navigator his longitude
and that the observation of the dip might enable him to determine his
latitude. But more extended observation shows that this was asking
altogether too much of the compass, and while it may be useful as
an accessory it is by no means the navigator's chief reliance in
determining his location. This is accomplished, as everyone is aware,
in clear weather by the observation of the heavenly bodies. In cloudy
weather, however, such observations obviously cannot be made, and the
seaman must direct his ship and estimate his location--an all important
matter when he is approaching the coast--by what is called dead
reckoning. One element of this reckoning is furnished by the compass,
inasmuch as that is his sole guide in determining the direction of
the ship's progress. The other element is supplied by the log which
furnishes him a clue as to the distance traversed hour by hour.
It is rather startling to reflect that the navigators of the middle
ages had no means whatever of determining the rate of progress of a
ship at sea, beyond the crudest guesses unaided by instrument of any
kind. When Columbus made his voyage he had no means of knowing what
distance he had actually sailed; nor was any method of measuring the
ship's speed utilized throughout the course of the ensuing century. In
the year 1570, however, one Humfray Cole suggested a theoretical means
of measuring the ship's rate of progress by means of an object dropped
back of the ship and allowed to drag through the water; and this
suggestion led a generation later to the introduction of the log, which
was first actually tested, so far as can be learned, in the year 1607.
The original log was so called because it consisted essentially of
an actual log or piece of wood. To the center of this a string was
attached, and in testing the ship's rate of progress this string was
allowed to slip through the fingers of a sailor who counted the number
of knots--placed, of course, at regular intervals on the string--that
passed through his fingers in a given time. As the log itself would
remain practically stationary in the water where it was dropped, the
number of knots counted indicated the distance traversed by the ship in
a given time. In practice the time was usually gauged by a half-minute
sand glass, and the knots were arranged at such a distance on the cord
that, in the course of the half minute, one knot would pass through
the fingers for each nautical mile covered by the ship in an hour. The
actual distance between the knots was therefore about fifty feet. The
nautical or geographical mile represents one degree of the earth's
circumference at the equator, amounting therefore to 6,008 feet, as
against the 5,280 feet of the statute mile. It was the use of the
log-line with its knots, as just explained, that led to the dubbing
of the nautical mile by the name "knot," which is still familiarly
employed, though the knotted log-line itself has been superseded in
recent times, except on very old-fashioned sailing ships.
The log retains its place even in the most modern ship, though its form
is materially altered, and its importance is somewhat lessened owing to
the fact that the experienced skipper can test the speed of his ship
very accurately by noting the number of revolutions per minute of the
ship's propellers. It is indeed the ship's propeller that supplies
the model for the modern log, in which the primitive piece of wood is
replaced by a torpedo-like piece of metal with miniature propeller-like
blades at its extremity. This apparatus is towed at the end of a long
line, and its blades, whirling more or less rapidly according to the
speed of the ship, communicate their motion to a recording apparatus,
adjusted at the ship's stern, to which the line is attached and the
face of which ordinarily presents a dial on which the speed of the ship
may be observed as readily as one observes the time by the clock.
Some recent modifications of the log employ an electrical device to
register the progress, but the principle of the revolving vanes, which
owe their speed to the rate at which they are dragged through the
water, is the fundamental one upon which the action of the log usually
depends, though attempts have been made to substitute pressure-gauge
systems.
While the modern log records the speed of the ship with a fair degree
of accuracy, its register shows at best only an approximation of the
facts. As already mentioned, the rate of revolution of the ship's
propeller blades furnishes what most navigators regard as a rather more
dependable test of speed. An apparatus for recording this is found on
the bridge of the modern ship. But due allowance must of course be made
for the effect of winds, waves, and ocean currents. These constantly
variable factors obviously make the estimate as to the precise distance
traversed by a ship in a given time a matter not altogether devoid of
guess work; and no navigator who has been obliged to sail for several
days by dead reckoning approaches a coast with quite the same degree
of satisfaction that he may entertain if his log has been checked by
observation of the sun or stars. In case, however, a navigator is able
to check his reckoning by astronomical observations, aided by the
chronometer, he determines his location with great accuracy.
THE DEVELOPMENT OF THE SEXTANT
The instrument with which such astronomical observations are made is
known as the sextant. Its purpose is to measure with great accuracy the
angle between two objects, which in practice are the horizon line on
one hand and some celestial body, usually the sun, on the other. The
determination of the latitude of the ship, for example, is a matter of
comparative ease, if the sun chances to be unobscured just at midday.
The navigator has merely to measure the exact elevation of the sun as
it crosses the meridian,--that is to say when it is at its highest
point,--and, having made certain corrections for so-called dip and
refraction, to which we shall refer more at length in a moment, a very
simple calculation reveals the latitude--that is to say, the distance
from the terrestrial equator.
That the latitude of a ship could thus be determined, with greater or
less accuracy, has been familiar knowledge to seamen from a very early
period. It was by the use of this principle that the earth was measured
by Eratosthenes and Posidonius in classical times, and the sailors of
antiquity probably carried with them a crude apparatus for measuring
the height of sun and stars, as the mediæval navigators are known to
have done.
The simplest and crudest form of measurer of which the record has been
preserved is known as the cross-staff. This consisted essentially of a
stick about a yard in length, called the staff, on which a cross-piece
was arranged at right angles, so adjusted at the center as to slide
back and forth on the staff. An eye-piece at one end of the staff was
utilized to sight along projections at either end of the cross-piece.
If the apparatus is held so that one of the lines of sight is directed
to the horizon, and then the cross-piece slid along the staff until
the other line of sight is directed toward the sun or a given star,
the angle between the two lines of sight will obviously represent the
angle of altitude of the celestial body in question. But the difficulty
of using an apparatus which requires two successive observations to be
made without shift of position is obvious, and it is clear that the
information derived from the cross-staff must have been at best very
vague--by no means such as would satisfy the modern navigator.
Even the navigators of the fifteenth century were aware of the
deficiencies of the cross-staff and sought to improve upon it. The
physicians of Henry the Navigator of Portugal, Roderick and Joseph by
name, and another of his advisers, Martin de Bohemia, are credited
with inventing, or at least introducing, a much improved apparatus
known as the astrolabe. This consists of a circle of metal, arranged
to be suspended from a ring at the side, so that one of its diameters
would maintain the horizontal position through the effect of gravity.
A superior quadrant of the circle was marked with degrees and minutes.
A straight piece of metal, with sights so that it could be accurately
pointed, was adjusted to revolve on a pivot at the center of the
circle. This sighting piece being aimed at the sun, for example, the
elevation of that body could be read directly on the measuring arc
of the circle. Here, then, was no new principle involved, but the
instrument had obvious points of advantage over the cross-staff, in
particular because only a single sight need be taken, the horizon
line being determined, as already explained, through the action of
gravitation.
The astrolabe did not gain immediate favor with practical navigators,
and it was at best a rather clumsy instrument, subject to peculiar
difficulties when used on a rolling ship. Many attempts were made to
improve upon it, but for a long time none of these was altogether
successful. The final suggestion as to means of overcoming the
difficulties encountered in measuring the altitude of astronomical
bodies was made by Sir Isaac Newton. But nothing practical came of
his discovery, as it was not published until a long time after his
death. Meantime independent discovery of the same principle was
made by Thomas Godfrey of Philadelphia, in 1730, and by the English
astronomer Hadley, who published his discovery before the Royal Society
in 1731. The instrument which Hadley devised was called a quadrant.
The principle on which it worked involved nothing more complex than
the use of two mirrors, one of them (known as the horizon glass and
having only half its surface mirrored) fixed in the line of vision of
a small telescope; the other (called the index mirror) movable with
the arm of an indicator, which is so adjusted as to revolve about the
axis of the quadrant. In operation these two mirrors enable the images
of two objects, the distance between which is to be measured, to be
superimposed. The telescope may be pointed at the horizon, for example,
directly under the position of the sun, and the arm of the instrument,
altering the position of the so-called index mirror, may be rotated
until the limb of the sun seems just to touch the horizon--the latter
being viewed through the unsilvered half of the horizon glass. The
scale at the circumference of the instrument is marked in half-degrees,
which, however, are registered as whole degrees, and which, so
interpreted, give the direct measurement of the angular distance
between the horizon and the sun; in other words the measurement of the
sun's altitude or so-called declination.
The instrument just described, perfected as to details but not modified
as to principles, constitutes the modern sextant, which is used by
every navigator, and which constitutes, along with the compass and
chronometer, the practical instrumental equipment that enables the
seaman to determine--by using the tables of the _Nautical Almanac_--his
exact position on the earth's surface from observation of the sun or
certain of the fixed stars. The modern instrument is called a sextant
because it has, for convenience' sake, been restricted in size to about
one-sixth of a circle instead of the original one-quarter, the small
size being found to answer every practical purpose, since it measures
all angles up to 120 degrees.
In practice the sextant is an instrument only six or eight inches in
diameter. It is held in the right hand and the movable radial arm is
adjusted with the left hand with the aid of a micrometer screw, and
the reading of the scale is made accurate by the vernier arrangement.
The ordinary observation--which every traveler has seen a navigator
make from the ship's bridge just at midday--is carried out by holding
the sextant in a vertical position directly in line of the sun, and
sighting the visible horizon line, meantime adjusting the recording
apparatus so as to keep the sun's limb seemingly in touch with the
horizon. As the sun is constantly shifting its position the vernier
must be constantly adjusted until the observation shows that the sun is
at the very highest point. The instrument being clamped and the scale
read, the latitude may be known when proper correction has been made
for the so-called dip, for refraction, and where great accuracy is
required for parallax.
[Illustration: "TAKING THE SUN" WITH THE SEXTANT.
The instrument is held in the right hand, and levelled at the horizon;
the left hand manipulating the micrometer screw which adjusts the
radial arm carrying the index mirror (at top of figure). The result is
read on the Vernier scale (arc at bottom of figure) with the aid of the
magnifying glass.]
Dip, it may be explained, is due to the fact that the observation is
made not from the surface of the water but from an elevation, which
is greater or less according to the height of the bridge, and which
therefore varies with each individual ship. The error of refraction
is due to the refraction of the sun's light in passing through the
earth's atmosphere, and will vary with the temperature and the degree
of atmospheric humidity, both of which conditions must be taken into
account. The amount of refractive error is very great if an object
lies near the horizon. Everyone is familiar with the oval appearance
of the rising or setting sun, which is due to refraction. With the sun
at the meridian, the refractive error is comparatively slight; and
when a star is observed at the zenith the refractive error disappears
altogether.
By parallax, as here employed, is meant the error due to the difference
in the apparent position of the sun as viewed by an observer at any
point of the earth's surface from what the apparent position would
be if viewed from the line of the center of the earth, from which
theoretical point the observations are supposed to be made. In the case
of bodies so distant as the sun, this angle is an exceedingly minute
one, and in the case of the fixed stars it disappears altogether. The
sun's parallax is very material indeed from the standpoint of delicate
astronomical observations, but it may be ignored altogether by the
practical navigator in all ordinary observations. There is one other
correction that he must make, however, in case of sun observations;
he must add, namely, the amount of semi-diameter of the sun to his
observed measurement, as all calculations recorded in the _Nautical
Almanac_ refer to the center of the sun's disk.
PERFECTING THE CHRONOMETER
The observation of the sun's height, with the various corrections just
suggested, suffices by itself to define the latitude of the observer.
Something more is required, however, before he can know his longitude.
How to determine this, was a problem that long taxed the ingenuity of
the astronomer. The solution came finally through the invention of the
chronometer, which is in effect an exceedingly accurate watch.
Time measurers of various types have, of course, been employed from the
earliest times. The ancient Oriental and Classical nations employed
the so-called clepsydra, which consisted essentially of receptacles
from or into which water dripped through a small aperture, the lapse of
time being measured by the quantity of water. At an undetermined later
date sand was substituted for the water, and the hour glass with which,
in some of its forms, nearly everyone is familiar, came into use. For
a long time this remained a most accurate of time measurers, though
efforts were early made to find substitutes of greater convenience.
Then clocks operated by weights and pulleys were introduced; and,
finally, after the time of the Dutchman Huygens, the pendulum clock
furnished a timepiece of great reliability. But the mechanism operated
by weight or pendulum is obviously ill-adapted to use on shipboard.
Portable watches, in which coiled springs took the place of the
pendulum, had indeed been introduced, but the mechanical ingenuity
of the watchmaker could not suffice to produce very dependable
time-keepers. The very idea of a watch that would keep time accurately
enough to be depended upon for astronomical observations intended to
determine longitude was considered chimerical.
Nevertheless the desirability of producing a portable time-keeper
of great accuracy was obvious, and the efforts of a large number
of experimenters were directed towards this end in the course of
the eighteenth century. These efforts were stimulated by the hope
of earning a prize of twenty thousand pounds offered by the British
Government for a watch sufficiently accurate to determine the
location of a ship with maximum error of half a degree, or thirty
nautical miles, corresponding to two minutes of time, in the course
of a transatlantic voyage. It affords a striking illustration of the
relative backwardness of nautical science, and of the difficulties
to be overcome, to reflect that no means then available enabled the
navigator at the termination of a transatlantic voyage to be sure of
his location within the distance of thirty nautical miles by any means
of astronomical or other observation known to the science of the time.
The problem was finally solved by an ingenious British carpenter
named John Harrison, who devoted his life to the undertaking, and
who came finally to be the most successful of watchmakers. Harrison
first achieved distinction by inventing the compensating pendulum--a
pendulum made of two metals having a different rate of expansion under
the influence of heat, so adjusted that change in one was compensated
by a different rate of change in the other. Up to the time of this
discovery, even the best of pendulum clocks had failed of an ideal
degree of accuracy owing to the liability to change of length of the
pendulum--and so, of course, to corresponding change in the rate of
its oscillation--with every alteration of temperature. Another means
of effecting the desired compensation was subsequently devised by Mr.
Graham, through the use of a well of mercury in connection with the
pendulum, so arranged that the expansion of the mercury upward in its
tube would compensate the lengthening of the pendulum itself under
effect of heat, and vice versa; but the Harrison pendulum, variously
modified in design, remains in use as a highly satisfactory solution of
the problem.
Harrison early conceived the idea that it might be possible to apply
the same principle to the balance-wheel of the watch. This problem
presented very great practical difficulties, but by persistent effort
these were finally overcome, and a balance-wheel produced, which, owing
to the unequal expansion and contraction of its two component metals
under changing temperature, altered its shape and so maintained its
rate of oscillation almost--though never quite--regardless of changing
conditions of temperature.
In 1761 Harrison produced a watch which was tested on a British ship
in a trip to the West Indies in that and the succeeding year, and
which proved to be a time-keeper of hitherto unexampled accuracy. The
inventor had calculated that the watch, when carried into the tropics,
would vary its speed by one second per day with each average rise
of ten degrees of temperature. Making allowance for this predicted
alteration, it was found that the watch was far within the limits of
variation allowed by the conditions of the test above outlined. It had
varied indeed only five seconds during the journey across the ocean.
On the return trip the watch was kept in a place near the stern of
the ship, for the sake of dryness, where, however, it was subjected
to a great deal of joggling, which led to a considerably greater
irregularity of action; but even so its variation on reaching British
shores was such as to cause a maximum miscalculation of considerably
less than thirty nautical miles.
Although Harrison seemed clearly enough to have won the prize,
there were influences at work that interfered for a time with full
recognition of his accomplishment. Presently he received half the
sum, however, and ultimately, after having divulged the secret of his
compensating balance and proved that he could make other watches of
corresponding accuracy, he received the full award.
Minor improvements have naturally been made in the watch since that
time, but the essential problem of making a really reliable portable
timepiece was solved by the compensating balance-wheel of Harrison.
The ship's chronometer of to-day is merely a large watch, with an
escapement of particular construction, mounted on gimbals so that it
will maintain a practically horizontal position.
Modern ships are ordinarily provided with at least three of these
time-keepers in order that each may be compared with the others, and
a more accurate determination of the time made than would be possible
from observation of a single instrument; inasmuch as no absolutely
accurate time-keeper has ever been constructed. Two chronometers would
obviously be not much better than one, since there would be no guide as
to whether any variation between them had been caused by one running
too fast or the other too slowly. But with a third chronometer to check
the comparison, it is equally obvious that a dependable clue will be
given as to the exact time.
It is to be understood of course that the variation of any of the
chronometers will be but slight if they are good instruments. Moreover
the tendency to vary in one direction or the other of each individual
instrument will be known from previous tests. Such tests are constantly
made at the Royal Observatory in England and elsewhere, and the
best chronometers bear certificates as to their accuracy and as to
their rate of variation. It may be added that a chronometer or other
timepiece is technically said to be a perfect instrument, not when
it has no variation at all--since this has proved an unattainable
ideal--but when its variation is slight, is always in one direction,
and is perfectly or almost perfectly uniform.
FINDING THE TIME WITHOUT A CHRONOMETER
In the reference made above to the testing of Harrison's watch, it
was stated that that instrument varied by only a certain number of
seconds in the course of the westerly voyage across the Atlantic, and
that its variation was somewhat greater on the return voyage. This
implies, clearly, that some method was available to test the watch in
the West Indies, without waiting for the return to England. At first
thought this may cause no surprise, since the local time can of course
be known anywhere through meridian observations; but on reflection
it may seem less and less obvious as to just what test was available
through which the exact difference in time between Greenwich, at
which the watch was originally tested, and local time at the station
in the West Indies could be determined. There are, however, several
astronomical observations through which this could be accomplished, and
in point of fact the comparative times and hence the precise longitudes
at many points on the Western Hemisphere--and indeed of all portions
of the civilized globe--were accurately known before the day of the
chronometer.
One of the simplest and most direct means of testing the time of a
place, as compared with Greenwich time, is furnished by observation
of the occultation of one of the moons of Jupiter. By occultation is
meant, as is well known, the eclipse of the body through passing into
the shadow of its parent planet. This phenomenon, causing the sudden
blotting out of the satellite as viewed from the earth, occurs at
definite and calculable periods and is obviously quite independent
of any terrestrial influence. It occurs at a given instant of time
and would be observed at that instant by any mundane witness to whom
Jupiter was at that time visible. If then an observer noted the exact
local time at which occultation occurred, and compared this observed
time with the Greenwich time at which such occultation was predicted
to occur, as recorded in astronomical tables, a simple subtraction
or addition will tell him the difference in time between his station
and the meridian at Greenwich; and this difference of time can be
translated into degrees of longitude by merely reckoning fifteen
degrees for each hour of time, and fractions of the hour in that
proportion.
It will be noted that this observation has value for the purpose
in question only in conjunction with certain tables in which the
movements of Jupiter and its satellite are calculated in advance. This
is equally true of the various other observations through which the
same information may be obtained--as for example, the observation of a
transit of Mars, or the measurement of apparent distance between the
moon and a given fixed star. Before the tables giving such computations
were published it was quite impossible to determine the exact longitude
of any transatlantic place whatsoever. We have already pointed out that
Columbus had only a vague notion as to how far he had sailed when he
discovered land in the West. The same vagueness obtained with all the
explorations of the immediately ensuing generations.
It was not until about the middle of the sixteenth century that
Mercator and his successors brought the art of map-making to
perfection; and the celebrated astronomical tables of the German Mayer,
which served as the foundation for calculations of great importance
to the navigator, were not published until 1753. The first _Nautical
Almanac_, in which all manner of astronomical tables to guide the
navigator were included, was published at the British Royal Observatory
in 1767.
At the present time, a navigator would be as likely to start on a
voyage without compass and sextant as without charts and a _Nautical
Almanac_. Indeed were he to overlook the latter the former would
serve but a vague and inadequate purpose. Yet, as just indicated, this
invaluable adjunct to the equipment of the navigator was not available
until well toward the close of the eighteenth century. But of course
numerous general tables had been in use long before this, else--to
revert to the matter directly in hand--it would not have been possible
to make the above-recorded test in the case of Harrison's famous watch
in the voyage of 1761-62.
ASCERTAINING THE SHIP'S LONGITUDE
In the days before the chronometer was perfected, almost numberless
methods of attempting to determine the longitude of a ship at sea were
suggested. There were astronomers who advocated observation of the
eclipse of Jupiter's satellites; others who championed the method of
so-called lunars--that is to say, calculation based on observation of
the distance of the moon at a given local time from one or another of
certain fixed stars arbitrarily selected by the calculator. Inasmuch as
the seaman could always regulate even a faulty watch from day to day
by observation of the meridian passage of the sun, it was thought that
these observations of Jupiter's satellite or of the moon would serve
to determine Greenwich time and therefore the longitude at which the
observation was made with a fair degree of accuracy. But in practice
it is not easy to observe the eclipse of Jupiter's satellite without a
fair telescope; and it was soon found that the tables for calculating
the course of the moon were by no means reliable, hence theoretically
excellent methods of determining longitude by observation of that body
proved quite unreliable in practice.
It was with the chief aim of bettering our knowledge of the moon's
course through long series of very accurate observations that the Royal
Observatory at Greenwich was founded. Perhaps it was not unnatural
under these circumstances that certain of the Astronomers Royal should
have advocated the method of lunars as the mainstay of the navigator.
In particular Maskelyne, who was in charge of the Observatory in
the latter part of the eighteenth century, was so convinced of
the rationality of this method that he was led to discredit the
achievements of Harrison's watches, and for a long time to exert an
antagonistic influence, which the watchmaker resented bitterly and it
would appear not without some show of reason.
Ultimately, however, the accuracy of the watch, and its
indispensableness in the perfected form of the chronometer, having been
fully demonstrated, the method of lunars became practically obsolete
and the mariner was able to determine his longitude with the aid of
sextant, chronometer, and _Nautical Almanac_, by means of direct
observation of the altitude of the sun by day and of sundry fixed stars
by night, a much simpler calculation sufficing than was required by the
older method.
As the sun is the chief time-measurer, whose rate of passage in a
seeming circumnavigation of the heavens is recorded by the dial of
clock, watch, or chronometer, it would seem as if the simplest
possible method of determining longitude would be found through
observation of the sun's meridian passage. The user of the sextant on
shipboard always makes, if weather permits, a meridian observation
of the sun, and such observation gives him an accurate gauge of the
altitude of the sun at its highest point and hence of his own latitude.
By adjusting the arm of the sextant with which this observation is
made, the observer is able to determine the exact point reached by the
sun in its upward course with all requisite accuracy.
But, unfortunately for his purpose, the sun does not poise for an
instant at the apex of its upward flight and then begin its descent. On
the contrary, its orbit being circular, the course of the sun just at
its highest point is approximately horizontal for an appreciable length
of time, and while the observer therefore has adequate opportunity to
measure with accuracy the highest point reached, he cannot possibly
make sure, within the limits of a considerable fraction of a minute, as
to the precise moment when the center of the sun is on the meridian. He
can, indeed, determine this point with sufficient accuracy for rough
calculations, but modern navigation demands something more than rough
calculations, inasmuch as a variation in time of one minute represents
one-quarter of a degree of longitude, or fifteen nautical miles at the
equator, and such uncertainty as this would imply can by no means be
permitted in the safe navigation of a ship that may be passing through
the water at the rate of a nautical mile in less than three minutes.
It follows that meridian observation of the sun, owing to the necessary
inaccuracy of such observation, is not the ideal method. In point of
fact the sun may be observed for this purpose to much better advantage
when it is at a considerable distance from the meridian, since then
its altitude above the horizon at a given moment is the only point
necessary to be determined. The calculation by which the altitude of
the sun may be translated into longitude is indeed more complicated
in this case; but while spherical trigonometry is involved in the
calculation, the tables supplied by the _Nautical Almanac_ enable the
navigator to make the estimate without the use of any knowledge beyond
that of the simplest mathematics.
MEASURING A DEGREE OF LATITUDE
While these observations tell the navigator his exact location in
degrees of latitude and longitude, such knowledge does not of course
reveal the distance traversed unless the precise length of the degree
itself is known; and this obviously depends upon the size of the
earth. Now we have seen that the earth was measured at a very early
date by Greek and Roman astronomers, but of course their measurements,
remarkable though they were considering the conditions under which
they were made, were but rough approximations of the truth. Numerous
attempts were made to improve upon these early measurements, but it
was not until well into the seventeenth century that a really accurate
measurement was made between two points on the earth's surface, the
difference between which, as measured in degrees and minutes, was
accurately known.
In June of the year 1633, the Englishman Robert Norman made very
accurate observations of the altitude of the sun on the day of the
summer solstice (when of course it is at its highest point in the
heavens); the observation being made with a quadrant several feet
in diameter stationed at a point near the Tower of London. On the
corresponding day of the following year he made similar observations at
a point something like 125 miles south of London, in Surrey. The two
observations determined the exact difference in latitude between the
two points in question.
Norman then undertook a laborious survey, that he might accurately
measure the precise distance in miles and fractions thereof that
corresponded to these known degrees of latitude. He made actual
measurements with the chain for the most part, but in a few places
where the topography offered peculiar difficulties he was obliged to
depend upon the primitive method of pacing.
The modern surveyor, equipped with instruments for the accurate
measuring of angles, not differing largely in principle from the
quadrant of the navigator, would consider Norman's method of
measurement a very clumsy one. He would measure only a single original
base line of any convenient length, but would make that measurement
with very great accuracy, using, perhaps, a rod packed in ice that
it might not vary in length by even the fraction of an inch through
changes in temperature. An accurate base line thus secured, he
would depend thereafter on the familiar method of triangulation, in
which angles are measured very accurately, and from such measurement
the length of the sides of the successive triangles determined by
simple calculation. In the end he would thus have made the most
accurate determination of the distance involved, without having
actually measured any portion thereof except the original base line.
Notwithstanding the crudity of Norman's method, however, his estimate
of the actual length of a degree of the earth's surface was correct,
as more recent measurements have demonstrated, within twelve yards--a
really remarkable result when it is recalled that the total length of
the degree is about sixty nautical miles.
Inasmuch as the earth is not precisely spherical, but is slightly
flattened at the poles, successive degrees of latitude are not
absolutely uniform all along a meridian, but decrease slightly as the
poles are approached. The deviation is so slight, however, that for
practical purposes the degree of latitude may be considered as an
unvarying unit. But obviously such is not the case with a degree of
longitude. The most casual glance at a globe on which the meridian
lines are drawn, shows that these lines intersect at the poles, and
that the distance between them is, in the nature of the case, different
at each successive point between poles and equator. It is only at the
equator itself that a degree of longitude represents 1/360 of the
earth's circumference. Everywhere else the parallels of latitude cut
the meridians in what are termed small circles--that is to say, circles
that do not represent circumference lines in the plane of the earth's
center. Therefore while all points on any given meridian of longitude
are equally distant in terms of degrees and minutes of arc from the
meridian of Greenwich, the actual distances from that meridian of the
different points as measured in miles will depend entirely upon their
latitude.
At the equator each degree of longitude corresponds to (approximately)
sixty miles, but in the middle latitudes traversed for example by the
transatlantic lines, a degree of longitude represents only half that
distance; and in the far North the meridians of longitude draw closer
and closer together until they finally converge, and at the poles all
longitudes are one.
It follows, then, that the navigator must always know both his latitude
and his longitude in order to estimate the exact distance he has
sailed. We have seen that a single instrument, the sextant, enables
him to make the observations from which both these essentials can be
determined. We must now make further inquiry as to the all important
guide without the aid of which his observations, however accurately
made, would avail him little. This guide, as already pointed out, is
found in the set of tables known as the _Nautical Almanac_.
THE NAUTICAL ALMANAC
Had the earth chanced to be poised in space with its axis exactly at
right angles to its plane of revolution, many computations of the
astronomer would be greatly simplified. Again, were the planetary
course circular instead of elliptical, and were the earth subject to
no gravitational influences except that of the sun and moon, matters
of astronomical computation would be quite different from what they
are. But as the case stands, the axis of the earth is not only tipped
at an angle of about twenty-three degrees, but is subject to sundry
variations, due to the wobbling of the great top as it whirls.
Then the other planets, notably the massive Jupiter, exert a perverting
influence which constantly interferes with the regular progression of
the earth in its annual tour about the sun. A moment's reflection makes
it clear that the gravitation pull of Jupiter is exerted sometimes in
opposition to that of the sun, whereas at other times it is applied in
aid of the sun, and yet again at various angles. In short, on no two
successive days--for that matter no two successive hours or minutes--is
the perturbing influence of Jupiter precisely the same.
What applies to the earth applies also, of course, to the varying
action of Jupiter on the moon and to the incessantly varied action of
the moon itself upon the earth. All in all, then, the course of our
globe is by no means a stable and uniform one; though it should be
understood that the perturbations are at most very slight indeed as
compared with the major motions that constitute its regular action and
lead to the chief phenomena of day and night and the succession of the
seasons.
Relatively slight though the perturbations may be, however, they are
sufficient to make noteworthy changes in the apparent position of the
sun and moon as viewed with modern astronomical instruments; and they
can by no means be ignored by the navigator who will determine the
position of his ship within safe limits of error. And so it has been
the work of the practical astronomers to record thousands on thousands
of observations, giving with precise accuracy the location of sun,
moon, planets, and various stars at given times; and these observations
have furnished the basis for the elaborate calculations of the
mathematical astronomers upon which the tables are based that in their
final form make up the _Nautical Almanac_, to which we have already
more than once referred.
These calculations take into account the precise nature of the
perturbing influences that are exerted on the earth and on the moon
on any given day, and hence lead to the accurate prediction as to the
exact relative positions of these bodies on that day. Stated otherwise,
they show the precise position in the heavens which will be held at
any given time by the sun for example, or by the important planets,
as viewed from the earth. How elaborate these computations are may be
inferred from the statement that the late Professor Simon Newcomb used
about fifty thousand separate and distinct observations in preparing
his tables of the sun. Once calculated, however, these tables of
Professor Newcomb are so comprehensive as to supply data from which the
exact position of the sun can be found for any day between the years
1200 B.C. and 2300 A.D., a stretch of some thirty-five centuries.
Such a statement makes it clear how very crude and vague the
deductions must have been from the observations of navigators, however
accurately made, prior to the time when such tables as those of the
_Nautical Almanac_ had been prepared. Fully to appreciate this, it
is necessary to understand that the observations supplied in such
profusion for the use of the mathematical astronomer are in themselves
subject to errors that might seriously vitiate the results of the final
computation. They must, therefore, be made with the utmost accuracy,
and with instruments specially prepared for the purpose. The chief
of these instruments is not the gigantic telescope but the small
and relatively simple apparatus known as a transit instrument. This
constitutes essentially a small telescope poised on very carefully
adjusted trunnions, in such a way that it revolves in a vertical
axis, bringing into view any celestial body that is exactly on the
meridian, and bodies in this position only. To make observation of
the transit--that is to say the passage across the meridian line--of
any given body more accurate, the transit instrument has stretched
vertically across the center of its field of vision a spider web, or a
series of parallel spider webs; in order, in the latter case, that the
mean time of several observations may be taken.
So exceedingly difficult is it to manufacture and mount an instrument
of requisite nicety of adjustment, that the effort has almost baffled
the ingenuity of the mechanic. Sir George Airy, in making a transit
instrument for use at the Royal Observatory at Greenwich, required the
trunnions on which it was to be mounted to be ground truly cylindrical
in form within a variation of one thirty-two-thousandth of an inch
as determined by a delicate spirit level. Even when all but absolute
decision has been obtained, however, it is quite impossible to maintain
it, as the slightest variation of temperature--due perhaps to the
application of the hand to one of the pillars on which the trunnions
rest--may disturb the precise direction of the spider webs and so
militate against absolute accuracy of observation. The instrument must,
therefore, be constantly tested and its exact range of errors noted and
allowed for.
To devote so much labor to details, merely in the effort to determine
the precise moment at which a star or planet crosses the meridian,
would seem to be an absurd magnification of trifles. But when we
reflect that the prime object of such observations is to supply
practical data which will be of service in enabling navigators on all
the seas of the globe to bring their ships safely to port, the matter
takes on quite another aspect. We have here, obviously, another and
a very striking illustration of the close relationship that obtains
between the work of the theoretical devotee of science and that of the
practical man of affairs.
SOUNDINGS AND CHARTS
Though the navigator, thanks to his compass, sextant, and _Nautical
Almanac_, may determine with a high degree of precision his exact
location, yet even the best observations do not enable him to approach
a coast without safeguarding his ship by the use of another piece of
mechanism calculated to test the depth of the waters in which he finds
himself at any given moment. In its most primitive form--in which form,
by the bye, it is still almost universally employed--this apparatus is
called the lead,--so called with much propriety because it consists
essentially of a lump of lead or other heavy weight attached to a small
rope. Knots in the rope enable the sailor who manipulates the lead to
note at a glance the depth to which it sinks. Most ocean travelers have
seen a sailor heaving the lead repeatedly at the side of the ship and
noting the depth of the water, particularly as the ship approached the
Long Island shore.
While this simple form of lead suffices for ordinary purposes, when
the chief information sought is as to whether the water is deeper than
the draft of the ship, it is at best only a rough and ready means of
testing the depth in relatively shallow waters. For deeper waters and
to test with greater accuracy the depths of uncharted regions, and in
particular to determine the character of the sea bottom at any given
place, more elaborate apparatuses are employed. One of the most useful
of these is the invention of the late Lord Kelvin. In this the lead
is replaced by a cannon ball, perforated and containing a cylinder
which is detached when the weight reaches the bottom and is drawn to
the surface filled with sand or mud, the cannon ball remaining at the
bottom. In another form of patent lead, a float becomes detached so
soon as the weight strikes the bottom and comes at once to the surface,
thus recording the fact that the bottom has been reached,--a fact not
always easy to appreciate by the mere feel of the line when the water
is fairly deep.
It is obvious that however well informed the navigator may be as to
his precise latitude and longitude, he can feel no safety unless he
is equally well informed as to the depth of the water, the proximity
of land, the presence or absence of shallows in the region, and the
like. He must, therefore, as a matter of course, be provided with maps
and charts on which these things are recorded. From the days when
navigation first became a science, unceasing efforts have been made
to provide such maps and charts for every known portion of the globe.
Geographical surveys, with the aid of the method of triangulation, have
been made along all coasts, and elaborate series of soundings taken for
a long distance from the coast line, and there are now few regions into
which a ship ordinarily sails, or is likely to be carried by accident,
for which elaborate charts, both of coast lines and of soundings, have
not been provided. The experienced navigator is able to direct his ship
with safety along coasts that he visits for the first time, or to enter
any important harbor on the globe without requiring the services of a
local pilot,--albeit the desire to take no undue risk makes it usual to
accept such services.
Time was, however, when maps and charts were not to be had, and when
in consequence the navigator who started on his voyages of exploration
was undertaking a feat never free from hazard. Until the time of
Mercator there was not even uniformity of method among map makers in
the charting of regions that had been explored. The thing seems simple
enough now, thanks to the maps with which every one has been familiar
since childhood. But it required no small exercise of ingenuity to
devise a reasonably satisfactory method of representing on a flat
surface regions that in reality are distributed over the surface of a
globe. The method devised by Mercator, and which, as everyone knows, is
now universally adopted, consists in drawing the meridians as parallel
lines, giving therefore a most distorted presentation of the globe, in
which the distance between the meridians at the poles--where in reality
there is no distance at all--is precisely as great as at the equator.
To make amends for this distortion, the parallels of latitude are not
drawn equidistant, as in reality they practically are on the globe, but
are spaced farther and farther apart, as we advance from the equator
toward either pole. The net result is that an island in the arctic
region would be represented on the map several times as large as an
island actually the same size but located near the equator. Doubtless
most of us habitually conceive Alaska and Greenland to be vastly more
extensive regions than they really are, because of our familiarity with
maps showing this so-called "Mercator's projection."
Of course maps are also made that hold to the true proportions,
representing the lines of latitude as equidistant and the meridians of
longitude as lines converging to a point at the poles. But while such
a map as this has certain advantages--giving, for example, a correct
notion of the relative sizes of polar and other land masses--it is
otherwise confusing inasmuch as places that really lie directly in
the north and south line cannot be so represented except just at the
middle of the map, and it is very difficult for the ordinary user of
the map to gain a clear notion as to the actual points of the compass.
A satisfactory compromise may be effected, however, by using Mercator's
projection for maps showing wide areas, while the other method is
employed for local maps.
THE LURE OF THE UNKNOWN
While the average man, even with well developed traveling instincts,
would perhaps prefer always to feel that he is sailing in well charted
waters and along carefully surveyed coasts, there have been in every
generation men who delighted in taking risks, and for whom half the
charm of a voyage must always lie in its dangers. Such men have been
the pioneers in exploring the new regions of the globe. That there was
no dearth of such restless spirits in classical times and even in the
dark ages, records that have come down to us sufficiently attest. For
the most part, however, their names have not been preserved to us. But
since the ushering in of the period which we to-day think of as the
beginning of modern times, records have been kept of all important
voyages of discovery, and at least the main outlines of the story of
the conquest of the zones are familiar to everyone.
Some of the earliest explorers, most notable among whom was the
Italian Marco Polo, traveled eastward from the Mediterranean and
hence journeyed largely by land. But soon afterward, thanks to
the introduction of the compass,--which instrument Marco Polo has
sometimes been mistakenly accredited with bringing from the East,--the
adventurers began to cast longing eyes out toward the western
horizons. Among the first conspicuous and inspiriting results were the
discoveries of the groups of islands known as the Cape Verdes and the
Azores. The Canary Islands were visited by Spaniards even earlier, and
became the subject of controversy with the other chief maritime nation
of the period, the Portuguese.
When the controversy was adjusted the Spaniards were left in possession
of the Canaries, but the Portuguese were given by treaty the exclusive
right to explore the coast of Africa. Following up sundry tentative
efforts, the daring Portuguese navigator, Bartholomeo Dias, in the
year 1487, passed to the southern-most extremity of Africa, which he
christened the Cape of Good Hope. At last, then, it had been shown
that Africa did not offer an interminable barrier to the passage to
the fabled land of treasures in the East. Before anyone had ventured
to follow out the clues which the discovery of the Cape had presented,
however, Columbus had seemingly solved the problem in another way by
sailing out boldly into the West and supposedly coming to the East
Indies in 1492.
The western route was barred to the Portuguese but the eastern one
remained open to them, and before the close of the century Vasco da
Gama had set out on the voyage that ultimately led him to India by way
of the Cape (1497-1500 A.D.). Twenty years later another Portuguese
navigator, Magellan by name, started on what must ever remain the most
memorable of voyages, save only that of Columbus. Magellan rounded the
southern point of South America and in 1521 reached the Philippines,
where he died. His companions continued the voyage and accomplished
ultimately the circumnavigation of the globe; and in so doing afforded
the first unequivocal practical demonstration, of a character
calculated to appeal to the generality of uncultured men of the time,
that the world is actually round.
Two routes from Europe to the Indies had thus been established, but
both of them were open to the objection that they necessitated long
detours to the South. To the geographers of the time it seemed more
than probable that a shorter route could be established by sailing
northward and coasting along the shores either of Europe to the East
or--what seemed more probable--of America to the West. Toward the
close of the sixteenth century the ships of the Dutch navigators had
penetrated to Nova Zembla, and a few years later Henry Hudson visited
Spitzbergen, thus inaugurating the long series of arctic expeditions.
Then Hudson, still sailing under the Dutch flag, made heroic efforts to
find the fabled northwest passage, only to meet his doom in the region
of the Bay that has since borne his name.
THE QUEST OF THE POLE
This was in the year 1610. For long generations thereafter successors
of Hudson were to keep up the futile quest; and when finally it
had been clearly established that no northwest passage to the
Pacific could be made available, owing to the climate, the zest for
arctic exploration did not abate, but its goal was changed from the
hypothetical northwest passage to the geographical pole.
Henry Hudson had in his day established a farthest North record of
about the eighty-second parallel of latitude--leaving only about five
hundred miles to be traversed. But three centuries were required in
which to compass this relatively small gap. Expedition after expedition
penetrated as far as human endurance under given conditions could carry
it. Some of the explorers returned with vivid tales of the rigors of
the arctic climate; others fell victim to conditions that they could
not overcome. But the seventeenth, eighteenth, and nineteenth centuries
passed and left the "Boreal Center" undiscovered.
Toward the close of the nineteenth century the efforts of explorers
seemed to be redoubled and one famous expedition after another
established new records of "farthest North." The names of Nansen, the
Duke of the Abruzzi, and Peary, became familiar to a generation whose
imagination seemed curiously in sympathy with that lure of the North
which determined the life activities of so many would-be discoverers.
So when in the early Autumn of 1909 it was suddenly announced that two
explorers in succession had at last, in the picturesque phrasing of one
of them, "penetrated the Boreal Center and plucked the polar prize,"
the popular mind was stirred as it has seldom been by any other event
not having either a directly personal or an international political
significance.
The two men whose claims to have discovered the pole were thus
announced in such spectacular fashion, were Dr. Frederick A. Cook,
of Brooklyn, and Lieutenant Commander Robert E. Peary, of the United
States Navy. Dr. Cook claimed to have reached the pole, accompanied
only by two Eskimo companions, on the twenty-first day of April, 1908.
Commander Peary reported that he had reached the pole, accompanied by
Mr. Matthew H. Henson and four Eskimos, on the seventh day of April,
1909.
The controversy that ensued regarding the authenticity of these
alleged discoveries is not likely to be forgotten by any reader of our
generation. Its merits and demerits have no particular concern for the
purely scientific inquirer. At best, as Professor Pickering of Harvard
is reported to have said, "the quest of the pole is a good sporting
event" rather than an enterprise of great scientific significance. It
suffices for our present purpose, therefore, to know that Dr. Cook's
records, as adjudged by the tribunal of the University of Copenhagen,
to which they were sent, were pronounced inadequate to demonstrate the
validity of his claim; whereas Peary and Henson were adjudged by the
American Geographical Society, after inspection of the records, to have
accomplished what was claimed for them. What has greater interest from
the present standpoint is the question, which the controversy brought
actively to the minds of the unscientific public, as to how tests are
made which determine, in the mind of the explorer himself, the fact of
his arrival at the pole.
The question has, indeed, been largely answered in the earlier pages
of this chapter, in our discussion of the sextant and the _Nautical
Almanac_; for these constitute the essential equipment of the arctic
explorer no less than of the navigators of the seas of more accessible
latitudes. There is one important matter of detail, however, that
remains to be noted. This relates to the manner of using the sextant.
On the ocean, as we have seen, the navigator levels the instrument at
the visible horizon; but it is obvious that on land or on the irregular
ice fields of the arctic seas no visible horizon can be depended upon
as a basis for measuring the altitude of sun or stars. So an artificial
horizon must be supplied.
The problem is solved by the use of a reflecting surface, which may
consist of an ordinary mirror or a dish of mercury. The glass reflector
must be adjusted in the horizontal plane with the aid of spirit levels;
mercury, on the other hand, being liquid, presents a horizontal surface
under the action of gravitation. Unfortunately mercury freezes at
about 39 degrees below zero; it is therefore often necessary for the
arctic explorer to melt it with a spirit lamp before he can make use
of it. These, however, are details aside from which the principles of
use of glass and mercury horizon are identical. The method consists
simply in viewing the reflected image of the celestial body--which in
practice in the arctic regions is usually the sun--and so adjusting the
sextant that the direct image coincides with the reflected one. The
angle thus measured will represent twice the angular elevation of the
body in question above the horizon,--this being, as we have seen, the
information which the user of the sextant desires.
Of course the explorer makes his "dash for the pole" in a season when
the sun is perpetually above the horizon. As he approaches the pole the
course of the sun becomes apparently more and more nearly circular,
departing less and less from the same altitude. Hence it becomes
increasingly difficult to determine by observation the exact time when
the sun is at its highest point. But it becomes less and less important
to do so as the actual proximity of the pole is approached; and as
viewed from the pole itself the sun, circling a practically uniform
course, varies its height in the course of twenty-four hours only
by the trifling amount which represents its climb toward the summer
solstice. Such being the case, an altitude observation of the sun may
be made by an observer at the pole at any hour of the day with equal
facility, and it is only necessary for him to know from his chronometer
the day of the month in order that he may determine from the _Nautical
Almanac_ whether the observation really places him at ninety degrees of
latitude. Nor indeed is it necessary that he should know the exact day
provided he can make a series of observations at intervals of an hour
or two. For if these successive observations reveal the sun at the same
altitude, it requires no _Almanac_ and absolutely no calculation of any
kind to tell him that his location is that of the pole.
The observation might indeed be made with a fair degree of accuracy
without the use of the sextant or of any astronomical equivalent
more elaborate than, let us say, an ordinary lead pencil. It is only
necessary to push the point of the pencil into a level surface of ice
or snow and leave it standing there in a vertical position. If, then,
the shadow cast by the pencil is noted from time to time, it will be
observed that its length is always the same; that, in other words,
the end of the shadow as it moves slowly about with the sun describes
a circle in the course of twenty-four hours. If the atmospheric
conditions had remained uniform, so that there was no variation in the
amount of refraction to which the sun's rays were subjected, the circle
thus described would be almost perfect, and would in itself afford a
demonstration that would appeal to the least scientific of observers.
An even more simple demonstration might be made by having an Eskimo
stand in a particular spot and marking the length of his shadow as cast
on a level stretch of ice or snow. Just twelve hours later let the
Eskimo stand at the point where a mark had been made to indicate the
end of the shadow, and it would be found that his present shadow--cast
now, of course, in the opposite direction--would reach exactly to the
point where he had previously stood. The only difficulty about this
simple experiment would result from the fact that the sun is never
very high as viewed from the pole and therefore the shadow would
necessarily be long. It might therefore be difficult to find a level
area of sufficient extent on the rough polar sea. In that case another
measurement similar in principle could be made by placing a pole
upright in the snow or ice and marking on the pole the point indicated
by the shadow of an Eskimo standing at any convenient distance away.
At any interval thereafter, say six or twelve hours, repeat the
experiment, letting the man stand at the same distance from the pole as
before, and his shadow will be seen to reach to the same mark.
Various other simple experiments of similar character may be devised,
any of which would appeal to the most untutored intelligence as
exhibiting phenomena of an unusual character. Absolutely simple as
these experiments are, they are also, within the limits of their
accuracy, absolutely demonstrative. There are only two places on the
globe where the shadow of the upright pencil would describe a circle,
or where the man's shadow would be of the same length at intervals of
twelve hours, or would reach to the same height on a pole in successive
hours. These two regions are of course the poles of the earth. It may
reasonably be expected that explorers who reach the poles will make
some such experiments as these for the satisfaction of their untrained
associates, to whom the records of the sextant would be enigmatical.
But for that matter even an Eskimo could make for himself a measurement
by using only a bit of a stick held at arm's length--as an artist
measures the length of an object with his pencil--that would enable
him to make reasonably sure that the sun was at the same elevation
throughout the day--subject, however, to the qualification that the
polar ice was sufficiently level to provide a reasonably uniform
horizon.
While, therefore, it appears that the one place of all others at which
it would be exceedingly easy to determine one's position from the
observation of the sun is the region of the pole, it must be borne in
mind that the low elevation of the sun, and the extreme cold may make
accurate instrumental observations difficult; and it is conceivable
that the explorer who had the misfortune to encounter cloudy weather,
and who therefore gained only a brief view of the sun, might be left
in doubt as to whether he had really reached the goal of his ambition.
Fortunately, however, the explorers who thus far claim to have reached
the pole record uninterruptedly fair weather, enabling observations to
be taken hour after hour. Under these circumstances, there could be no
possibility of mistake as to the general location, although perhaps no
observation, under the existing conditions, could make sure of locating
the precise position of the pole within a few miles.
A curious anomaly incident to the unique geographical location of
the pole is that to the observer stationed there all directions are
directly south. Yet of course all directions are not one, and the query
may arise as to how an explorer who has reached the pole may know in
what direction to start on his return voyage. The answer is supplied
by the compass, which--perforce pointing straight south--indicates the
position of the magnetic pole and so makes clear in which direction
lies the coast of Labrador. Moreover if the explorer is provided with
reliable chronometers, which of course record the time at a given
meridian--say that of Greenwich--these will enable him to determine by
the simplest calculation what particular region lies directly beneath
the sun at any given time. If, for example, his chronometer shows five
o'clock Greenwich time, he knows that the sun's position, as observed
at the moment, marks the meridian five hours (_i.e._, 75° of longitude)
west of Greenwich.
While the arctic region appears thus to have given up its last secret,
this is not as yet true of the antarctic. The expedition of Lieutenant
(now Sir Ernest) Shackleton, in 1908, approached within about one
hundred and eleven miles of the South Pole. The intervening space--less
than two degrees in extent--represents, therefore, the only stretch of
latitude on the earth's surface that has not been trodden by man's foot
or crossed by his ships. More than one expedition is being planned to
explore this last remaining stronghold, and in all probability not many
years--perhaps not many months--will elapse before the little stretch
of ice that separated Lieutenant Shackleton from the South Pole will be
crossed, and man's conquest of the zones will be complete.
II
THE HIGHWAY OF THE WATERS
There is no doubt that the use of sails for propelling boats is as old
as civilization itself. We know that the Egyptians used sails at least
4,000 years before the Christian era. They did not depend entirely upon
the sails, however, but used oars in combination with them. Steering
was done with single or double oars lashed to the stern and controlled
by ropes or levers. This method of steering remained in use until late
in the Middle Ages, the invention of the rudder being one of the few
nautical inventions made during the centuries immediately following
that unproductive period of history known as the Dark Age.
Following the Egyptians, the Phœnicians were the greatest maritime
nation of ancient times, but unfortunately they have left no very
satisfactory and authentic records describing their boats. In all
probability, however, their ships were galleys having one or two banks
of oars, fitted with sails similar to those of the Egyptians.
If our knowledge of Phœnician boats is meager, our knowledge of Greek
boats, particularly the fighting craft, is correspondingly full. From
the nature of its geographical location Greece was necessarily a
maritime nation, and it was here that boat-building reached a very
high state of development during the period of Greek predominance.
Large ships fitted with sails and having several banks of rowers were
used habitually in commerce and war, and it was here also that the
management of sails became so well understood that oars were often
dispensed with except as auxiliaries.
It was in Greece that the custom of having several banks of oars
superimposed reached its highest development, but the fabulous number
of such banks credited by some authors seems to be entirely without
foundation. It is possible that as many as seven banks were used,
although the evidence in favor of more than five is very slight.
The writings of Callixenos describe a ship said to have been used by
Ptolemy Philopater, which was a forty-banker. This ship is described as
450 feet long, 57 feet broad, carrying a crew of about 7,000 men, of
whom 4,000 were rowers. This description need not be taken seriously,
as there is no proof that boats of such proportions were ever attempted
in ancient times. But it is certain that the Greeks did build large
vessels, some of them at least one hundred and fifty feet long--perhaps
even larger than this. The tendency of shipbuilders during the later
Greek period was to build large, unwieldy boats, which used sails
under favorable circumstances, but depended entirely upon oars for
manœuvering in battle.
The Romans used similar vessels of large size until the time of the
battle of Actium, where the clumsy, many-banked ships of Antony and
Cleopatra were destroyed by the lighter single- or double-banked
vessels of Augustus. Augustus had adopted the low, swift, handy vessels
of a piratical people, the Liburni, who had learned in their sea fights
against all kinds of vessels that the lighter type of boat could be
used most effectively. Structurally the hulls of these boats were not
unlike modern wooden vessels.
While the various types of vessels were being developed in the
Mediterranean region, a race of mariners far to the north were
perfecting boats in which they were destined to overrun the Western
seas from the tropics to the arctic circle. These people, the Norsemen,
left few written descriptions that give a good idea of the construction
of their boats, which were sufficiently seaworthy to enable the Danes
to cross the Atlantic and colonize America. But thanks to one of their
peculiar burial customs some of their smaller boats have been preserved
and brought to light in recent years. It was their custom when a great
chief died, to bury him in a ship, heaping earth over it to form a
great mound. In most instances the wood of such boats, buried for a
thousand years, has entirely disappeared; but in some mounds the boats
have been preserved almost intact.
From the specimens so preserved it is known that the Norsemen knew
how to shape the hulls of their boats almost as well as the modern
boat-builder. This fact is interesting because the immediate successors
of the Norsemen, either through ignorance or choice, reverted to most
primitive types in building their boats. Thus it required centuries for
them to develop a knowledge of hull-construction that was familiar in
ancient times to the northern rovers. Scandinavia itself never entirely
forgot the art, and there are boats built in Norway to-day closely
similar in all essentials to some of the boats constructed by the
Norsemen.
MEDIÆVAL SHIPS
The contrast in shape and construction between the trim ships of the
Norsemen and the short, top-heavy vessels which were the approved
European type during the early Middle Ages, is most striking. The
Mediæval shipbuilders in striving to improve their craft, making them
as seaworthy and as spacious as possible, first added decks, and then
built towering superstructures at bow and stern. The result was a
vessel which would have been so top-heavy that it would be likely to
capsize had it not been so broad that "turning turtle" was out of the
question.
It was in such ships that Columbus made his voyage of discovery in
1492, although the superstructures fore and aft on his boat were
less exaggerated than in some later vessels. Nevertheless they were
veritable "tubs"; and we know from the experience of the crew that
sailed the replica of the _Santa Maria_ across the ocean in 1893, that
they were anything but comfortable craft for ocean traveling.
This replica of the _Santa Maria_ was reproduced with great fidelity
by the Spanish shipbuilders, and, manned by a Spanish crew, crossed
the ocean on a course exactly following that taken by Columbus on his
first voyage. Sir George Holmes' terse description of this voyage is
sufficiently illuminating without elaboration. "The time occupied was
thirty-six days," he says; "and the maximum speed attained was about 6½
knots. The vessel pitched horribly!"
Two full centuries before the discovery of America the rudder had
been invented. There is no record to show who was responsible for
this innovation, although its superiority over the older steering
appliances must have been appreciated fully. But after the beginning of
the fourteenth century the rudder seems to have come into general use,
entirely supplanting the older side-rudder, or clavus.
MODERN SAILING SHIPS
For a full century after the voyage of Columbus little progress was
made in ship construction; short, stocky boats, with many decks high
above the water-line at bow and stem continuing to be the most popular
type. In the opening years of the seventeenth century, however,
the English naval architect, Phineas Pett, departed from many of
the accepted standards of his time, and produced ships not unlike
modern full-rigged sailing vessels, except that the stern was still
considerably elevated, and the bow of peculiar construction. One of
Pett's ships, _The Sovereign of the Seas_, was a vessel 167 feet long,
with 48 foot beam, and of 1,683 tons burthen. The introduction of this
type of vessel was a distinct step forward toward modern shipbuilding.
[Illustration: THE OLD AND THE NEW--A CONTRAST
The replica of Henry Hudson's famous _Half Moon_, a typical fighting
ship of the 16th century, and a modern submarine. The photograph
was taken in New York Harbor during the Hudson-Fulton celebration,
September, 1909.]
The tendency of shipbuilders during the eighteenth century was to
increase the length of vessels in proportion to the breadth of beam
and diminish the depth of the hull and superstructures, above the
water line, with improved sailing qualities. England's extensive trade
with India and the far East was conducive to this development, as the
"East Indiamen" were necessarily a combination of merchant vessel and
battleship.
In the first half of the nineteenth century America rose to great
commercial importance thanks to her fleets of fine sailing vessels.
Speed rather than strength in their ships was the aim of American
ship-builders, to gain which they built boats proportionately longer
and narrower than ever constructed before for ocean traffic. The
culminating type of wooden sailing ship was represented by the
"Baltimore clippers," in which the length was five, and even six,
times the beam, with light rigging and improved mechanical devices for
handling it, whereby the amount of manual labor was greatly lessened.
One of these ships, the _Great Republic_, built in 1853, was over three
hundred feet long, and 3,400 tons register. She was a four-masted
vessel, fitted with double topsails, with a spread of canvas about
4,500 square yards.
The modern descendant of the wooden clipper ship is the schooner with
from four to six masts. Some of these vessels exceed the older boats
in size and carrying capacity, if not in speed. Perhaps the largest
schooner ever constructed is the _Wyoming_, which was completed at
Bath, Maine, early in the year 1910. This vessel is 329 feet long
and 50 feet broad. It has a carrying capacity of 6,000 tons. The
construction of such a vessel at so recent a period suggests that the
day of the sailing ship is by no means over notwithstanding that a
full century has elapsed since the coming of the steamboat. Here, as
so often elsewhere in the history of progress, it has happened that
the full development of a type has not been reached until the ultimate
doom of that type, except for special purposes, had been irrevocably
sealed. Ever since the full development of the steamboat in the early
decades of the nineteenth century, the sailing ship has seemed almost
an anachronism; and yet, in point of fact, the steamship did not at
once outrival its more primitive forerunner. Even in the matter of
speed, the sailing ship more than held its own for a generation or
so after the steamship had been placed in commission. In 1851 the
American clipper _Flying Cloud_ made 427 knots in twenty-four hours;
and _The Sovereign of the Seas_ bettered this by averaging over
eighteen miles an hour for twenty-four consecutive hours. The Atlantic
record for sailing vessels is usually said to have been made in 1862
by the clipper ship _Dreadnought_ in a passage between Queenstown
and New York, the time of which is stated as nine days and seventeen
hours. It should be remarked, however, that the authenticity of this
extraordinary performance has been challenged.
Be that as it may, it is certain that the speediest sailing ships,
granted favorable conditions of wind and wave, more than surpassed
the best efforts of the steamship until about the closing decades of
the nineteenth century. But of course long before this the steamship
had proved its supremacy under all ordinary conditions. Even though
sailing ships continued to be constructed in large numbers, their
picturesque rigging became less and less a feature in all navigable
waters, and the belching funnel of the steamship had become a
characteristic substitute as typifying the sea-going vessel.
The story of the development of this new queen of the waters must now
demand our attention. It begins with the futile efforts of several more
or less visionary enthusiasts who were contemporaries of James Watt,
and who thought they saw great possibilities in the steam engine as a
motive power to take the place of oars and sails for the propulsion of
ships.
EARLY ATTEMPTS TO INVENT A STEAMBOAT
Among the first of these was an American named John Fitch. Judged by
the practical results of his efforts, he was not a highly successful
inventor; as a prophet, however, and as an experimenter whose efforts
fell just short of attainment, he deserves a conspicuous place in the
history of an epoch-making discovery. Yet his prophecy was based on his
failures. From 1780, for twenty years he strove to perfect a steamboat.
His efforts did not carry him far beyond the experimental stage. But
his courage and enthusiasm never waned. "Whether I bring the steamboat
to perfection or not," he declared, "it will some time in the future be
the mode of crossing the Atlantic for packets and armed vessels."
At that very time Benjamin Franklin said this would never be. But
twenty years later Fulton's _Clermont_ paddled up the Hudson River
from New York to Albany and opened the era that saw Fitch's prophecy
fulfilled. This was in 1807--a year that must stand as the most
momentous in maritime history. In that year the little _Clermont_
steamed slowly from New York to Albany, a distance of one hundred
and fifty miles in thirty-two hours, unaided by sails or oars, and
propelled entirely by steam-power. A sail-boat could cover the distance
in the same number of hours; a modern torpedo boat in one-sixth the
time. Yet no performance of any boat, before or since, had such
far-reaching effects upon the progress of the world.
When Fulton turned his attention from his favorite theme--the invention
of a submarine boat--and took up the question of perfecting a boat
propelled by steam, he did not find himself the first or the only
inventor in the field. For a hundred years, in round numbers, men had
been wrestling with the question of applying steam pressure to boat
propulsion. All manner of more or less ingenious devices had been
conceived, most of them having a germ of success in the principles
involved, but all of them being failures in actual practice.
Among the most promising of these first steamboats were those in which
the propeller, or the paddle-wheel, was tried; but neither of these
methods was looked upon favorably at first. Less promising was one in
which the motive power was a jet of water pumped through a submerged
tube--a principle that still periodically fascinates certain modern
inventors.
[Illustration: MARINE ENGINES AND AN EARLY TYPE OF STEAMBOAT.
The small figure in the centre represents a very remarkable steamboat
constructed in America by John Fitch. The precise date of its
construction is not clearly established, but the inventor had made
efforts at steam navigation as early as 1776. The upper figure shows a
marine engine made in Scotland in 1788 for Patrick Miller by William
Symington. It was used to equip a double-hulled pleasure boat which it
is said to have propelled at the rate of five miles an hour. The motive
power is supplied by two open-top Newcomen cylinders. The lower figure
represents a modern side wheel steamer with oscillating engines.]
But the boats that seemed to have come nearer attaining practical
success for the moment were those in which several sets of oars
worked by steam were placed vertically on each side of the hull, the
machinery so arranged that the oars were dipped into the water and
drawn sternward by one motion of the machinery, raised and carried
toward the bow by the opposite motion. In some of these boats it was
planned to have four sets of oars, two sets on each side, which were to
work alternately, so that while one set was traveling forward through
the air, its mate would be paddling through the water, thus insuring a
continuous forward impulse. But the machinery for these boats proved
to be too cumbersome and complicated for practical results, and this
idea was finally abandoned. The jet of water did not prove any more
successful, and but two other methods were available--the propeller and
the paddle-wheel.
Both of these methods of utilizing the power of moving water had been
familiar in the form of the Archimedian screw and the commonplace
overshot or undershot mill-wheel. In these examples, of course,
the force of the water was used to move machinery, reversing the
action of the paddle-wheel of the boat. And yet the principles were
identical. Obviously if the conditions were reversed, and the undershot
mill-wheel, for example, forced against the water with corresponding
power, the propulsive effect might be great enough--since action and
reaction are equal--to move a boat of considerable size. But curiously
enough, at the time when Fulton began his experiments there was a wave
of general belief that when this principle was applied to boats it
would fail. The reason for this lay in the fact that several such boats
had been built from time to time, and all had failed. The fault, of
course, lay in some other place than in their paddle wheels; but for
the time being the wheel, and not the machinery, was shouldered with
the blame.
Just a hundred years before Fulton finally produced his practical
paddle-wheel steamboat, a prototype was built by the Spaniard, Blasco
de Gary. In 1707, this inventor constructed a model paddle-wheel
steamboat, and tried it upon the river Fulda. But this model boat
failed to work, and the experiment was soon forgotten.
Twenty-five years later Jonathan Hulls of England patented a marine
engine which he proposed to use in a boat which was to be propelled by
a stern wheel. His idea was to use his boats as tug- or tow-boats, and
to equip the larger vessels themselves with steam. But his engines were
defective and his boats did not achieve commercial success.
During the time of the American Revolution, a French inventor, the
Marquis de Jouffroy, made several interesting experiments with
steam-propelled boats, using the principle of the paddle which was
dipped and raised alternately as referred to a few pages back. His
boats made several public trials, one of them ascending the Seine
against the current; but nevertheless, the French government refused
to grant the inventor a patent. Presumably, therefore, the boat was
not considered a practical success in official circles; and this view
is tacitly conceded by the fact that no more boats of its type were
constructed. Had they been really practical steamboats it is a fair
presumption that others would have been constructed and put into
operation, regardless of patents. Nevertheless, in France to-day,
the Marquis de Jouffroy is often referred to as the father of steam
navigation.
The idea of propelling a boat by means of a jet of water pumped out at
the stern by steam pumps was given a practical test in 1784, by James
Rumsey. His boat made a trial trip on the Potomac River in September
of that year, General Washington and other army officers being present
on this occasion. The boat was able to make fairly good progress
through the water, and seemed so promising that a company was formed
by capitalists known as the Rumsey Society, for promoting the idea and
building more boats. Rumsey was sent to England where he undertook the
construction of another boat, meanwhile taking out patents in Great
Britain, France, and Holland. Before his boat was completed, however,
he died suddenly, and the Rumsey Society passed out of existence
shortly afterwards.
An even closer approach to practical success was made in Scotland by
James Symington, who in 1788, in association with two other Scotchmen,
Miller and Taylor, constructed a boat consisting of two hulls, with a
paddle-wheel between them worked by a steam-engine. This boat worked
so well that in 1801, Lord Dundas engaged Symington to build a smaller
boat to be used for towing on the Caledonian Canal. This boat, called
the _Charlotte Dundas_, completed in 1802, is said to have been capable
of towing a vessel of one hundred and forty tons "nearly four miles an
hour." But in doing this the resulting "wash" so threatened the banks
of the canal that the vessel was laid up and finally rotted and fell to
pieces.
By many impartial judges this boat is considered the first practical
steamboat, and its failure to establish its claim due to the force
of circumstances rather than to any inherent defects. Symington was
too poor to pursue his work independently, and was deterred by the
attitude of James Watt, who "predicted the failure of his engine,
and threatened him with legal penalties if it succeeded." And when at
last he received an order for eight smaller vessels from the Duke of
Bridgewater, his patron died before the details of the agreement had
been completed. So that while he failed in accomplishing what was done
by Fulton a few years later, it is certain that, as Woodcraft says, "He
combined for the first time those improvements which constitute the
present system of steam navigation."
Some of Symington's engines have been preserved, and one of them is now
in the Patent Office Museum in London. Since the beginning of practical
steam navigation this engine has been tested several times, the result
showing that Woodcraft's estimate is not overdrawn.
While Symington was thus perfecting a paddle-boat, an American, Col.
John Stevens of Hoboken, New Jersey, was on the verge of accomplishing
the same end with a screw-propeller boat--a form of steamship that did
not come into use until some forty years later.
[Illustration: THE STEAMSHIPS "CHARLOTTE DUNDAS" AND "CLERMONT."
The "Charlotte Dundas" (lower figure) was built in 1801 by A. Hart at
Grangemouth, Scotland, and engined by William Symington, for service on
the Forth and Clyde Canal. Its length was 56 feet; beam 18 feet; depth
8 feet. The boat was a practical success, but its use was discontinued
because of the damage done to the banks of the Canal by the wash of
the paddles. The upper left-hand figure is a picture of Fulton's
"Clermont." The diagram at the right represents the "Clermont's" paddle
wheels and the mechanism by which they were worked.]
Stevens also invented what he called a "rotary engine" which was really
an engine constructed on the same principle as the modern turbine
engine. It was a small affair which he placed in a skiff, and used for
turning the screw-propeller of a boat which was able to travel at a
rate of three or four miles an hour on the North River, during the fall
of 1802. But Stevens found so much difficulty in packing the blades of
this engine without causing too much friction that he finally abandoned
it for the more common type of reciprocating engine. But if this little
steamboat had its defects, it nevertheless contained the germs of two
great features of steam navigation--the screw propeller and the turbine
engine, the advantage of the first of which was not recognized for
nearly half a century, and the other not until almost a full century
later.
In 1804 Stevens produced another propeller steamboat, this one using
the ordinary type of reciprocating engine, and being notable for having
twin screws of a pattern practically identical with the screws now in
use. This boat was able to steam at a rate of four miles an hour on
many occasions, and at times almost double this rate, according to some
observers. The engines of this boat are still in existence, and on
several occasions since 1804 have been placed in hulls corresponding
as nearly as possible to the original, and have demonstrated that
they could force the boat through the water at six or eight miles an
hour. These engines in a modern hull were exhibited at the Columbian
Exposition at Chicago, in 1893. They supply irrefutable evidence that
the practical steamboat had been invented at least three years before
Fulton's historic voyage in 1807. Yet no one questions that it was
Fulton's, not Stevens', invention that inaugurated steam navigation.
Just why this was so is a little difficult to comprehend at this time,
unless it was that Stevens' boat was such a small affair that it did
not attract the attention it deserved, as did Fulton's larger boat.
And yet we should not be guided too much by retrospective judgment.
The significant fact remains that Stevens himself did not have entire
confidence in his boat, or in the principle of his screw propeller, as
is shown by the fact that three years later, while Fulton was building
the _Clermont_, Stevens was also constructing a steamboat, not along
the lines of his previous inventions, but as a paddle-wheel boat. This
leaves little room for doubt that Stevens had not full confidence in
the propeller; and when an inventor himself mistrusts his own device,
there is little likelihood that anyone else will supply the necessary
confidence. This may account for the fact that Stevens found difficulty
in securing financial backing for his enterprise; and when such backing
was found it was for the construction of the paddle-wheel boat, which
was finished a few months after Fulton's boat had solved the problem of
steam navigation.
FULTON AND THE CLERMONT
As we shall see in another place, Fulton was no novice in the
construction of peculiar boats at this time. He had built experimental
boats both at home and abroad, was familiar with the principle of the
screw and the paddle-wheel, and had come to have absolute confidence
in the possibility of propelling boats at a good rate of speed by the
use of steam. When he began his now famous _Clermont_, in the spring of
1807, it was not as an experimental skiff, but as a boat of one hundred
and fifty tons burden--half again the size of the boats in which
Columbus had discovered America--to be placed in commission between
Albany and New York city. By August, this boat was completed, and the
engines in place, and, under her own steam, the new boat was moved
from the Jersey shipyard where she was constructed, and tied up at a
New York dock. On August 7th, she started on her maiden trip up the
Hudson. To the astonishment of practically every one of the persons in
the great throng that had gathered along the shores, she left her dock
in due course, and with wind and tide against her, steamed up the river
at the rate of about five miles an hour. At this speed she covered
the entire distance between New York and Albany, settling forever the
question of the practicability of steam navigation.
The impression this fire-belching monster made upon the sleepy
inhabitants as it passed along the river can be readily imagined. An
eye-witness account of this first passage of the _Clermont_ has been
given by an inhabitant at the half-way point near Poughkeepsie.
"It was the early autumn in 1807," he wrote, "that a knot of villagers
was gathered on the high bluff just opposite Poughkeepsie, on the
west bank of the Hudson, attracted by the appearance of a strange,
dark-looking craft which was slowly making its way up the river. Some
imagined it to be a sea-monster, while others did not hesitate to
express their belief that it was a sign of the approaching Judgment.
What seemed strange in the vessel was the substitution of lofty and
straight black smoke-pipes, rising from the deck, instead of the
gracefully tapered masts that commonly stood on the vessels navigating
the stream; and, in place of spars and rigging, the curious play of the
working-beam and pistons, and the slow turning and splashing of the
huge, naked paddle-wheels, met the astonished gaze. The dense clouds of
smoke as they rose wave upon wave, added still more to the wonderment
of the rustics.
"This strange looking craft was the _Clermont_, on her trial trip to
Albany. On her return-trip, the curiosity she excited was scarcely
less intense--the whole country talked of nothing but the sea-monster,
belching fire and smoke. The fishermen became terrified and rowed
homewards, and they saw nothing but destruction devastating their
fishing grounds; whilst the wreaths of black vapor, and rushing noise
of the paddle-wheels, foaming with the stirred-up water, produced great
excitement among the boatmen."
[Illustration: THE CLERMONT
The replica of Robert Fulton's first steamboat which took part in the
Hudson-Fulton celebration in September, 1909. The small picture shows
one of the paddle-wheels in detail. The original _Clermont_, the first
commercially successful steamboat, was put in commission for the New
York-Albany service in 1807.]
While acknowledging fully Fulton's right to the claim of being "the
father of steam navigation," as he has been called, there is no
evidence to show that he introduced any new principle or discovery
in his application of steam to the _Clermont_. The boiler, engine,
paddle-wheel--every part of the boat had been known for years. Yet
this does not detract from the glory of Fulton, who first combined
this scattered knowledge in a practical way, and demonstrated the
practicality beyond question.
SEA-GOING STEAMSHIPS
The first war steamer and ocean steamer ever attempted was built by
Fulton, in 1813. It was called the _Demolgos_, and was not a practical
success, and made no attempts to take protracted ocean voyages. The
first steamship to cross was the _Savannah_ in 1819. She made the
voyage from Savannah to Liverpool in twenty-five days, using her
paddle-wheels part of the time, but at other times depending entirely
upon her sails. She was a boat of three hundred and fifty tons, and her
paddle-wheels were arranged so that they could be hauled in upon the
deck and stowed away in bad weather.
Following the _Savannah_ several similar combination sailing and
steam-propelled boats were constructed, the navigators coming to have
more and more faith in the possibilities of steam, so that less sail
was carried. These vessels continued to reduce the time of the passage
between Europe and America, until the voyage had been made in about
seventeen days. Then, in 1838, two vessels, the _Sirius_ and the _Great
Western_, for the first time using steam alone as motive power, made
record voyages, the _Great Western_ crossing in twelve days, seven and
a half hours. This was considered remarkable time--an average speed of
over two hundred miles a day. Something like four hundred and fifty
tons of coal were consumed on the voyage, which impressed many as a
great extravagance of fuel. Some of the ocean liners at present consume
more than twice this amount in a single day.
On July 4, 1840, the _Britannia_, the first steamer of the Cunard
Line, started on its maiden voyage from Liverpool to Boston. The
voyage was made in fourteen days, among the passengers being Samuel
Cunard, a Quaker of Halifax, who was the founder of the enterprise.
The population of Boston went mad on the arrival of this boat; streets
and buildings were decorated, and the day was given over to the
regular holiday amusements. Cunard received upward of eighteen hundred
invitations to dinner that evening.
The year 1840, then, may be considered as one of the vital years
in the progress of steam navigation. Since that time no year has
passed without seeing some important addition and improvement made
in the conquest of the ocean, either in size, shape, or speed of the
"greyhounds."
SHIPS BUILT OF IRON AND STEEL
Even before the introduction of steam as a motive power for boats
shipbuilders had been casting about for some satisfactory substitute
for wood in the construction of vessels. One reason for this was that
suitable wood was becoming scarce and very expensive. But also there
was a limit to the size that a wooden vessel might be built with
safety. A wooden boat more than three hundred feet long cannot be
constructed without having dangerous structural weakness.
Naturally the idea that the only suitable material for boat-building
was something lighter than water,--something that would float--which
had been handed down traditionally for thousands of years, could not be
overcome in a moment. And surely such a heavy substance as iron would
not be likely to suggest itself to the average ship-builder. But at the
beginning of the nineteenth century rapid strides were being made in
theoretical, as well as applied science, and the idea of using metal in
place of wood for shipbuilding began to take practical form.
Richard Trevithick, whose remarkable experiments in locomotive building
have been noted in another chapter, had planned an iron ship as early
as 1809. He did not actually construct a vessel, but he made detailed
plans of one--not merely a boat with an iron hull, but with decks,
beams, masts, yards, and spars made of the same material. It was nearly
ten years after Trevithick drew his plans, however, before the first
iron ship was constructed. Then Thomas Wilson of Glasgow built a vessel
on practically the same lines suggested by Trevithick.
This vessel, finished in 1818, and called the _Vulcan_, was the pioneer
of all iron boats. For at least sixty years it remained in active
service. Indeed, for aught that is known to the contrary, this first
iron boat may be still in use in some capacity.
One of the most surprising and interesting things to shipbuilders
about the _Vulcan_, and the boats that were constructed after her,
was the fact that they were actually lighter in proportion to their
carrying capacity than ships of corresponding size built of wood. In
wooden cargo ships the weight of the hull and fittings varies from 35
to 45 per cent. of the total displacement, while iron vessels vary from
25 to 30 per cent. This was a vital point in favor of the iron vessel,
and one that appealed directly to practical builders. But the public
at large looked askance at the new vessels. To "sink like a stone" was
proverbial; and everyone knows that iron sinks quite as readily as
stone.
But very soon a convincing demonstration of the strength of iron
vessels brought them into favor. A great storm, sweeping along the
coast of Great Britain in 1835, drove many vessels on shore, among them
an iron steamboat just making her maiden voyage. The wooden vessels
without exception were wrecked, most of them destroyed, but the iron
vessel, although subjected to the same conditions, escaped without
injury, thanks to the material and method of her construction.
From that time the position of the iron steamship was assured. And
whereas sea voyagers had formerly looked askance at iron passenger
boats they now began to distrust those built of wood. By the middle of
the century, iron shipbuilding was at its height, and in the decade
immediately following, the _Great Eastern_ was finished--possibly the
largest and most remarkable structure ever built of iron, on land or
sea. In recent years larger ships have been constructed, but these
ships are made of steel.
The _Great Eastern_ marked an epoch in shipbuilding. In size she was a
generation ahead of her time, but the innovations in the method of her
construction gave the cue to modern revolutionary shipbuilding methods.
Sir George C. V. Holmes gives the following account of the great ship:
"She was originally intended by the famous engineer, Mr. I. K. Brunel,
to trade between England and the East. She was designed to make the
voyage to Australia without calling anywhere _en route_ to coal, a feat
which, in the then state of steam-engine economy, no other vessel could
accomplish. It was supposed that this advantage, coupled with the high
speed expected from her great length, would secure for her the command
of the enormous cargoes which would be necessary to fill her. Mr.
Brunel communicated his idea that such a vessel should be constructed
for the trade to the East to the famous engineer and shipbuilder, the
late Mr. John Scott Russell, F.R.S., and he further persuaded his
clients, the directors of the Eastern Steam Navigation Company, of the
soundness of his views, for they resolved that the projected vessel
should be built for their company, and entrusted the contract for its
execution to the firm of John Scott Russell & Co., of Millwall.
"Mr. Scott Russell and Mr. Brunel were, between them, entitled to the
credit of the design, which, on account of the exceptional size of the
ship, presented special difficulties, and involved a total departure
from ordinary practice.
"Mr. Scott Russell had systematically, in his own previous practice,
constructed iron ships with cellular bottoms, but the cells had only
five sides, the uppermost side on the inside being uncovered. Over
a large portion, however, of the bottom of the _Great Eastern_ the
cells were completed by the addition of an inner bottom, which added
greatly both to the strength and to the safety of the ship. It was
also Mr. Brunel's idea that the great ship should be propelled by both
paddles and screw. Mr. Scott Russell was responsible for the lines and
dimensions, and also for the longitudinal system of framing, with its
numerous complete and partial transverse and longitudinal bulkheads.
"The following are some of the principal dimensions and other _data_ of
the _Great Eastern_:
Length between perpendiculars 680 feet
Length on upper deck 692 "
Extreme breadth of hull 83 "
Width over paddle-box 120 "
Depth from upper deck to keel 58 "
Draught of water (laden) 30 "
Weight of iron used in construction 10,000 tons
Number of plates used in construction 30,000
Number of rivets used in construction 3,000,000
Tonnage, gross 18,914 tons
Nominal power of paddle engine 1,000 H. P.
Nominal power of screw engines 1,600 "
"The accommodation for passengers was on an unprecedented scale. There
were no less than five saloons on the upper, and as many on the lower
deck, the aggregate length of the principal apartments being 400 feet.
There was accommodation for 800 first-class, 2,000 second-class, and
1,200 third-class passengers, and the crew numbered 400. The upper
deck, which was of a continuous iron-plated and cellular structure,
ran flush from stem to stern, and was twenty feet wide on each side of
the hatchways; thus two spacious promenades were provided, each over a
furlong in length. The capacity for coal and cargo was 18,000 tons.
"The attempts to launch this vessel were most disastrous, and cost no
less than £120,000, an expense which ruined the company. The original
company was wound up, and the great ship sold for £160,000 to a new
company, and was completed in the year 1859. The new company very
unwisely determined to put her on the American station, for which she
was in no way suited. During her preliminary trip the pilot reported
that she made a speed of fully 14 knots at two-thirds of full pressure,
but the highest rate of speed which she attained on this occasion was
15 knots, and on her first journey across the Atlantic the average
speed was nearly 14 knots, the greatest distance run in a day having
been 333 nautical miles. The great value of the system adopted in her
construction was proved by an accident which occurred during one of her
Transatlantic voyages. She ran against a pointed rock, but the voyage
was continued without hindrance. It was afterwards found that holes of
the combined length of over 100 feet had been torn in her outer bottom;
but, thanks to the inner water-tight skin, no water was admitted."
Between the years 1860 and 1870 great improvements were made in marine
engines, and screw-steamers very generally replaced side-wheel boats
for ocean traffic. The improvements in the engines consisted largely
in the use of higher pressures, surface condensation, and compounding
of the cylinders, which resulted in a saving of about half the amount
of fuel over engines of the older type. As a result steamers were able
to compete successfully with the sailing ships, even as freighters for
long voyages, such as those between Europe and Australia.
During the reactive period in France immediately following the
Franco-Prussian war, when there was great activity in shipbuilding,
the use of mild steel plates in place of wrought iron was tried. The
superiority of this material over iron was quickly demonstrated, and
as the cost of steel was constantly lessening, thanks to the newly
discovered methods of production, steel practically replaced iron in
ship construction after this time.
It was during this same period that a new type of passenger steamer was
produced--the "ocean greyhound." The first of these was the _Oceanic_,
built by the White Star Company in 1871. This ship was remarkable in
many ways. Her length, four hundred and twenty feet, was more than
ten times her beam; iron railings were substituted for bulwarks; and
the passenger quarters were shifted from the position near the stern
to the middle of the vessel. All these changes proved to be distinct
improvements, and the _Oceanic_ became at once the most popular, as
well as the fastest ocean liner.
Like all the other boats of the seventies and early eighties, the
_Oceanic_ was a single-screw vessel. The advantage of double propellers
in case of accident had long been recognized, but hitherto twin-screws
had not proved as efficient as a single screw in developing speed. But
in 1888 the _City of Paris_ (now the _Philadelphia_) a twin-screw boat,
began making new speed records, and the following year her sister ship,
the _New York_, and the new _Majestic_ and _Teutonic_, entering into
the ocean-record contests, cut the time of the passage between Europe
and America to less than six days.
The advantages of the double-screw over the single are so many and so
manifest as to leave no question as to their superiority. The disabling
of the shaft or screw of the single-screw steamer, or the derangement
of her rudder renders the vessel helpless. Not so the twin-screw ship;
for on such ships the screws can be used for steering as well as
propelling. And it has happened many times that twin-screw ships have
crossed the ocean with the steering gear disabled, or with one screw
entirely out of commission.
THE TRIUMPH OF THE TURBINE
In recent years the greatest revolutionary step in steamship
construction has been the invention and development of the turbine
engine, the mechanism of which has been described elsewhere. Since
the day of the little _Turbinia_, whose speed astonished the nautical
world, the limit for size and speed of ships has again been materially
advanced, and no thinking person will venture to predict restricting
limits without a modifying question mark.
At the beginning of the twentieth century a keen rivalry had developed
between England and the Continent for supremacy in transatlantic
traffic, America having dropped out of the race. The Germans in
particular had produced fast boats, such as the _Deutschland_ and
_Kaiser Wilhelm II_, which for several years held the ocean record for
speed. But meanwhile the turbine engine was being perfected in England,
the land of its invention, and presently turbine "greyhounds" began
crossing the ocean and menacing the records held by the boats equipped
with the older type of engine.
The reciprocating marine engine, however, had been steadily improved,
until it was a marvel in efficiency. Quadruple expansion engines
driving twin-screws of a size and shape known to develop the greatest
efficiency, for several years offered invincible competition to the new
type of engine. There were new conditions to be met, new difficulties
to be overcome.
A decisive test of the merits of the turbine engine was given in
1905, when the Cunard Company built two vessels, the _Caronia_ and
_Carmania_, of exactly the same size and shape, the _Caronia_ having
the highest type of quadruple expansion reciprocating engines, while
the _Carmania_ was equipped with turbine engines. Here was a fair
test of efficiency between the two types. And the turbine boat proved
herself the better of the two by developing more than a knot greater
speed per hour.
Still the _Carmania_ offered no serious competition in speed to
several of the German flyers. But in 1908 two more turbine ships,
the _Lusitania_ and _Mauretania_ began making regular transatlantic
voyages, and quickly distanced all competitors.
In size as well as in speed these sister ships mark an epoch in
navigation. Turbine engines take the place of the usual reciprocating
type, acting on four propellers for going ahead, and two separate
propellers for going astern. These engines develop 68,000 horse-power.
Stated in this way these figures convey little idea of the power
developed. But when we say that it would take a line of horses one
hundred and twenty miles long hitched tandem to develop the power
generated in the compact space of the _Mauretania's_ engine room, some
idea of the power is gained.
It is not the matter of power, size, or speed alone that makes the
twentieth century passenger steamer so completely outclass her
predecessors. It is really the matter of comfort and safety afforded
the ocean travelers. Safety against sinking from injury to the hull
was provided for by the introduction of watertight compartments half a
century ago, as we have seen; and the size of the _Great Eastern_ has
been surpassed in only a few instances. But it is since the beginning
of the present century that two revolutionary safety devices have been
perfected--wireless telegraphy and the submarine signaling apparatus.
The wireless apparatus has been described in another chapter, and as
it is used almost as much on land as at sea, cannot be considered as
solely a nautical appliance. But the submarine signaling device, which
is dependent upon water for transmission, is essentially a nautical
mechanism.
SUBMARINE SIGNALING
It is difficult for the average landsman to appreciate that the one
thing most dreaded by mariners is fog. Dark and boisterous nights
which frighten the distressed landsman have no terrors for the sailor.
Given an open sea-way he knows that he can ride out any gale that
blows. It is the foggy night that fills him with apprehension.
In perfectly still weather the sound of the fog horn carries far
enough, and indicates location well enough so that two ships
approaching each other, or a ship approaching a bell buoy, can detect
its location and avoid danger. But this is under favorable conditions;
and unfortunately such conditions do not always prevail. And if there
is a wind stirring or the sea running high atmospheric sounds cannot be
depended upon. A fog whistle whose sound ought to carry several miles
under ordinary conditions, may not be heard more than a ship's length
away. And scores of accidents, such as collisions between ships, have
happened in fogs, when both vessels were sounding their fog whistles at
regular intervals.
When wireless telegraphy was perfected sufficiently to be of
practical use, great hopes were entertained that this discovery could
be used to give warning and prevent accidents to fog-bound vessels. But
experience has shown that its usefulness is confined largely to that
of calling for help after the accident, rather than in preventing it.
Thus in 1908 when the wireless operator on board the steamer _Republic_
flashed his message broadcast telling ships and shore-stations for
hundreds of miles around that his vessel had been run down in a fog
and was sinking, he could only give the vessels that hurried to the
_Republic's_ aid an approximate idea of where they could find her. The
use of another electric appliance, of even more recent invention than
the wireless telegraph, was necessary for locating the exact position
of the stricken ship. This was the submarine signaling device, which
utilizes water instead of air as a medium for transmitting sound.
Benjamin Franklin pointed out more than a century ago that water
carries sound farther and faster than air, and carries it with greater
constancy. Density, temperature, and motion of the atmosphere act upon
aerial sound waves to reflect and refract them in varying degrees;
but these waves are not affected when water is the medium through
which they are passing. The knowledge of these facts was turned to
little practical account until the closing years of the last century
when Arthur J. Mundy of Boston, and a little later Prof. Elisha Gray
of Chicago, began experiments together that resulted finally in a
practical submarine signaling apparatus which is now installed as
a system on boats and buoys in dangerous places along the coasts,
particularly near the great highways of ocean travel.
The principle upon which this system is based is simply that of sound
waves transmitted through the water and detected at a distance by a
submerged electrical transmitter. The sound transmitted is usually
that of a submerged bell. It is possible for a person whose head is
submerged to hear the ringing of such a bell distinctly for a long
distance; but of course for practical purposes such submergence is out
of the question. The receiving apparatus of the Mundy-Gray signaling
device offers a substitute in the form of a submerged "artificial
ear"--an electrical transmitter, connected with a telephone receiver.
In the early experiments a small hollow brass ball filled with water
and containing a special form of electrical transmitter was lowered
over the side of a ship and connected by insulated wires to the
receiver of a telephone in the pilot house. The sound of a submerged
bell could be heard in this manner at a distance of ten or twelve
miles. The location of the bell could be determined by having two
such brass balls, one on each side of the hull of the vessel but not
submerged to a depth below that of the hull, so that the ship itself
acts as a screen in obstructing the sound waves coming from the bell.
By listening alternately to the sounds of the bell transmitted through
these two submerged balls it was found that the ball on the side of the
ship toward the bell gave a distinctly louder sound. By turning the
ship so that the sounds were of equal intensity the direction of the
bell could be determined as either directly ahead or astern; and by
using the compass the exact location could be determined.
But such brass-ball transmitters can be used only when the vessel
is moving at a rate not exceeding three miles an hour. They are,
therefore, of little value for ocean liners whose reduced speed far
exceeds this. But the inventors discovered presently that by using the
inside of the outer steel skin of the ship's hull below the water line
as one side of the brass ball, the transmitter would work equally well.
Indeed, with added improvements, this hollow metal device fastened to
the inside of the hull on each side, with connecting wires leading to
the pilot house, in its perfected form will pick up the sound of the
submerged bell equally well at any speed, regardless of calm or storm.
The chief defect of this arrangement was that the sound of the
pulsations of the engines of the ship were also heard, and interfered
seriously with the detection of the sound of the bell. But presently
a receiving device was perfected which ignored all sounds but those
of the bell, thus giving the mariner a means of protection against
accidents that could be depended upon absolutely at all times
regardless of speed or weather conditions.
When this stage of perfection of the signaling device was reached
the various governments began installing the instruments on buoys,
lighthouse sites, and light-ships, using various mechanical devices for
ringing the bells, and timing the strokes so that the mariners could
tell by the intervals just what bell he was in touch with, as he knows
each lighthouse by the intervals between the Hashes of its lights. A
further development in the signaling device was to equip ships with
submerged bells, as well as with the receiving apparatus. In this way
two ships could communicate with each other, or with a shore receiving
station, by using the Morse telegraph code, just as in the case of
telegraphy.
The maximum distance at which such communications may be detected is
about fifteen miles, and the approximate distance from the bell can be
gauged from the clearness of the sound heard in the telephone receiver.
At the distance of a quarter of a mile the sound of the bell is so
loud that it is painful to the listener if the receiver is held against
the ear, while at ten or twelve miles the sound is scarcely audible.
Probably the most dramatic rescue at sea in recent years was that
of the passengers and crew of the steamer _Republic_, referred to a
few pages back. When her wireless messages of distress were received
a score of vessels went groping in the fog to her assistance, while
the entire civilized world waited in breathless expectancy. Most
of the rescuing vessels, although constantly in communication with
the stricken ship, were unable to locate her. But the successful
vessel finally got in touch with the _Republic's_ submarine signaling
apparatus, and aided by this located the vessel and rescued the crew
and passengers.
This is only one instance of the practical application of the submarine
signaling apparatus. But its use is not confined to the larger boats.
The apparatus can be made so small that even boats the size of a
fishing dory may be equipped at least with the sounding device, and
thus protected.
On the Newfoundland fishing banks one of the chief causes of loss of
life is the running down of the fishing boats in the fog by passing
steamers, and also the loss of the dories of the fishermen who are
unable to find their way back to their vessels. Many of these fishing
vessels now supply each of the attending dories with a submarine bell
which weighs about forty pounds and is run by clockwork. When caught
in the fog the fisherman hangs this bell over the side of his dory and
thus warns approaching steamers of his position, at the same time
affording his own vessel a guide for finding him and picking him up. In
this manner the appalling loss of life in the fogs on the fishing banks
has been greatly lessened. Thus the submarine signaling device gives
aid to the smaller craft as well as the larger vessels.
For the moment this is the last important safety device that has been
invented to help lessen the perils of sea voyages. Indeed the perils
and discomforts of ocean voyages are now largely reminiscent, thanks
to the rapid succession of scientific discoveries and their practical
application during the last half century. The size of modern vessels
minimizes rolling and pitching. Turbine engines practically eliminate
engine vibrations. The danger from fires was practically eliminated by
the introduction of iron and steel as building material; the danger of
sinking after collisions is now guarded against by the division of the
ship's hull into water-tight compartments; sensitive instruments as
used at present warn the mariner of the presence of ice-bergs; wireless
telegraphy affords a means of calling aid in case of disabled machinery
and giving the ship's location in a general way; while the submarine
signal makes known the exact location of the stricken vessel in foggy
weather.
In a trifle over half a century the time of crossing the Atlantic has
been reduced by more than one-half. In 1856 the _Persia_ crossed the
ocean between Queenstown and New York in nine days, one hour, and
forty-five minutes, making a new record. In 1909 the _Mauretania_
covered the same distance in four days, ten hours, and fifty-one
minutes. In March, 1910, the same vessel completed a passage over
the longer winter course, a distance of 2,889 knots, in four days,
fifteen hours, and twenty-nine minutes, reducing the previous record by
twenty-nine minutes.
When the _Lusitania_ and _Mauretania_ were completed many short-sighted
persons predicted that these vessels would never be surpassed in size
or speed. As if to refute such predictions, however, the White Star
Company at once began constructing two vessels, the _Olympic_ and
_Titanic_, each with a displacement of one-fourth more than the great
Cunarders, and of overshadowing proportions in everything save the
matter of speed. Against the _Mauretania's_ average twenty-six knot
speed the new boats are designed to make only twenty-one.
These new boats are eight hundred and ninety feet in length, as against
the _Lusitania's_ seven hundred and ninety. They are ninety-two feet in
beam, and sixty-two feet in molded depth. The roof of the pilot house
is seventy feet above the water. The maximum draft is thirty-seven and
a half feet and the displacement sixty thousand tons.
They resemble the _Great Eastern_ in that they have two systems
of engines. Two reciprocating engines drive the two outer of the
three screws, and the exhaust from these engines is utilized in a
low-pressure turbine engine, driving the center propeller.
LIQUID FUEL
Another step that has been taken to increase the efficiency of the
steam engine on ships, is the adoption of liquid fuel in place of coal
for making steam. For years the advantages of this form of fuel have
been recognized, the Russians having brought its use to a high state of
perfection, both in boats and locomotives. Practically all the steamers
on the Black and Caspian seas, as well as on such rivers as the Volga,
burn oil exclusively. And early in 1910 the British Navy decided to
substitute oil for coal on all its vessels.
The advantages claimed for oil over coal as fuel are many. It is
smokeless, produces more heat than coal, occupies less space for
storage, can be loaded more quickly and easily, is cleaner, and reduces
the engine-room force to one-fourth or one-third the number of men
required when coal is used. Incidentally it reduces the difficult
physical task of stoking to one relatively pleasant and easy. It
gives a steadier fire, does not foul the boilers, and does away with
cumbersome ashes and clinkers.
Its disadvantage lies in the danger from fire. An inflammable
liquid carried in a ship's hold is obviously more dangerous than a
corresponding quantity of relatively incombustible coal. Yet the
obvious advantages of this form of fuel have been so compelling that it
is now coming into use on all classes of war vessels, and seems likely
to supplant coal entirely on some types of boats, such as the torpedo
destroyers. Moreover, the experience of the Russian boats on the Black
and Caspian seas seems to indicate that the dangers from the use of
oil as a fuel when properly handled have been greatly exaggerated,
and passenger and freight steamers all over the world are gradually
adopting it.
Some tests were made by the Navy Department of the United States in
1909-1910 using a vessel which was formerly a coal-burning boat.
In these tests it was found that the steaming radius was greatly
increased, the firing force reduced, and fuel taken into the ship in
about one-fourth the time it takes to coal. It was possible to get up
steam in any boiler, or set of boilers, much more quickly than with
coal.
Of course where oil is used for fuel some special form of burner is
necessary. Many types have been tried, but in the most effective the
oil is atomized by the use of steam spray, or air blast, it being
impossible to get proper combustion of the oil except when used in
minutely divided particles. Used in this manner a uniform temperature
can be maintained easily, or may be increased or decreased very quickly.
As used at present liquid fuel simply substitutes coal for heating the
ordinary type of boiler. But there seems every reason to believe that
in the near future some type of internal combustion engine will be
perfected that will use the crude, cheap oil, as the finer and lighter
oils are used in motors to-day. When this occurs the space-consuming
boilers and furnaces used in ships at present will be replaced by
compact machinery, quite as efficient, but occupying only a fraction of
the space. Nor need we expect that the invention of some such type of
engine will be long delayed, if we may judge by the rapid strides made
in perfecting other internal combustion engines during the past few
years.
III
SUBMARINE VESSELS
The development of submarine vessels has been one of the slowest in
the history of modern inventions. Submarine boats, using submarine
torpedoes, were able to destroy ships a hundred years ago; and a little
less than half a century ago naval vessels were destroyed in actual
warfare by these boats. But curiously enough no vessel has ever been
destroyed in actual warfare by a submarine boat since that time. Yet
these boats are essentially war-vessels, and, with the exception of
boats of the Lake type, of no use whatever for commercial purposes.
Perhaps the explanation for this tardy development lies in the fact
that until recent years naval men have not looked with favor upon this
style of fighting craft. In Admiral Porter's book, written in 1878,
he makes the statement that one of the reasons why they did not show
more enthusiasm about the submarine made by Robert Fulton early in
the nineteenth century, was that such boats "menaced the position of
the naval men, whose calling would be gone did the little submarine
boat supplant the battle-ship." We need not, however, depend upon
this statement, made as it was three-quarters of a century after the
demonstrations by Fulton, for there are many similar statements made
at the time to be had at first hand. Thus Admiral Earl St. Vincent,
when opposing the views of William Pitt, who had become enthusiastic
over the possibilities of Fulton's submarines, is on record as having
opposed such craft on the ground that by encouraging such development
"he was laying the foundation which would do away with the navy." In
1802, M. St. Aubin wrote in this connection, "What will become of the
navies, and where will sailors be found to man ships of war, when it is
a physical certainty that they may at any time be blown into the air by
diving boats, against which no human foresight can guard them?"
Such opposition has undoubtedly tended to retard the progress of
submarine navigation; but be the cause what it may, it has made slow
and laborious work of it; and we are only now approaching a solution
of the question that seemed almost within grasp a hundred years
ago--before the days of steam or electricity.
THE FIRST SUBMARINE
As early as the sixteenth century the possibilities of submarine
navigation was the dream of the mariner, and tentative attempts at
submarine boats are said to have been made even at an earlier period
than this; but the first practical submarine boat capable of navigation
entirely submerged for any length of time was made by David Bushnell,
of Westbrook (then Saybrook), Maine, U. S. A., in 1775. Details as to
the construction of the remarkable craft, are recorded in a letter
written by the inventor to Thomas Jefferson in 1789, and recorded
in the _Transactions of the American Philosophical Society_. In this
letter Bushnell says:--
"The external shape of the submarine vessel bore some resemblance to
the upper tortoise shells of equal size, joined together, the place
of entrance into the vessel being represented by the opening made by
the swell of the shells at the head of the animal. The inside was
capable of containing the operator and air sufficient to support him
thirty minutes without receiving fresh air. At the bottom, opposite to
the entrance, was fixed a quantity of lead for ballast. At one edge,
which was directly before the operator, who sat upright, was an oar
for rowing forward and backward. At the other edge was a rudder for
steering. An aperture at the bottom, with its valves, was designed to
admit water for the purpose of descending, and two brass forcing-pumps
served to eject the water within when necessary for ascending. At
the top there was likewise an oar for ascending or descending, or
continuing at any particular depth. A water-gauge or barometer
determined the depth of descent, a compass directed the course, and
a ventilator within supplied the vessel with fresh air when on the
surface.
"The vessel was chiefly ballasted with lead fixed to its bottom; when
this was not sufficient a quantity was placed within, more or less
according to the weight of the operator; its ballast made it so stiff
that there was no danger of oversetting. The vessel, with all its
appendages and the operator, was of sufficient weight to settle it very
low in the water. About two hundred pounds of lead at the bottom for
ballast could be let down forty or fifty feet below the vessel; this
enabled the operator to rise instantly to the surface of the water in
case of accident.
"When the operator would descend, he placed his foot upon the top of a
brass valve, depressing it, by which he opened a large aperture in the
bottom of the vessel, through which the water entered at his pleasure;
when he had admitted a sufficient quantity he descended very gradually;
if he admitted too much he ejected as much as was necessary to obtain
an equilibrium by the two brass forcing-pumps which were placed at each
hand. Whenever the vessel leaked, or he would ascend to the surface, he
also made use of these forcing-pumps. When the skillful operator had
obtained an equilibrium he would row upward or downward, or continue at
any particular depth, with an oar placed near the top of the vessel,
formed upon the principle of the screw, the axis of the oar entering
the vessel; by turning the oar one way he raised the vessel, by turning
it the other he depressed it.
"An oar, formed upon the principle of a screw, was fixed in the fore
part of the vessel; its axis entered the vessel, and being turned one
way, rowed the vessel forward, but being turned the other way rowed it
backward; it was made to be turned by the hand or foot.
"Behind the submarine vessel was a place above the rudder for carrying
a large powder magazine. This was made of two pieces of oak timber,
large enough when hollowed out to contain one hundred and fifty pounds
of powder, with the apparatus used in firing it, and was secured in
its place by a screw turned by the operator. A strong piece of rope
extended from the magazine to the wood screw above mentioned, and was
fastened to both. When the wood screw was fixed to be cast off from
its tube, the magazine was to be cast off likewise by unscrewing it,
leaving it hanging to the wood screw; it was lighter than the water,
that it might rise up against the object to which the wood screw and
itself were fastened.
"Within the magazine was an apparatus constructed to run any proposed
length of time under twelve hours; when it had run its time it
unpinioned a strong lock resembling a gun-lock, which gave fire to the
powder. This apparatus was so pinioned that it could not possibly move
till, by casting off the magazine from the vessel, it was set in motion.
"The skillful operator could swim so low on the surface of the water
as to approach very near a ship in the night without fear of being
discovered, and might, if he chose, approach the stem or stem above the
water with very little danger. He could sink very quickly, keep at any
depth he pleased, and row a great distance in any direction he desired
without coming to the surface, and when he rose to the surface he could
soon obtain a fresh supply of air. If necessary, he might descend again
and pursue his course.
"After various attempts to find an operator to my wish, I sent one
who appeared more expert than the rest from New York to a fifty-gun
ship lying not far from Governor's Island. He went under the ship
and attempted to fix the wooden screw in her bottom, but struck, as
he supposed, a bar of iron which passes from the rudder hinge, and
is spiked under the ship's quarter. Had he moved a few inches, which
he might have done without rowing, I have no doubt but that he would
have found wood where he might have fixed the screw, or if the ship
were sheathed with copper he might easily have pierced it; but not
being well skilled in the management of the vessel, in attempting to
move to another place he lost the ship. After seeking her in vain for
some time he rowed some distance and rose to the surface of the water,
but found daylight had advanced too far that he durst not renew the
attempt. He says that he could easily have fastened the magazine under
the stem of the ship above the water, as he rowed up to the stern and
touched it before he descended. Had he fastened it there the explosion
of one hundred and fifty pounds of powder (the quantity contained in
the magazine) must have been fatal to the ship. In his return from the
ship to New York he passed near Governor's Island, and thought he was
discovered by the enemy on the island. Being in haste to avoid the
danger he feared, he cast off the magazine, as he imagined it retarded
him in the swell, which was very considerable. After the magazine had
been cast off one hour, the time the infernal apparatus was set to run,
it blew up with great violence."
[Illustration: ROBERT FULTON.]
ROBERT FULTON'S EXPERIMENTS
The work begun by Bushnell in 1775 was taken up ten years later by
Robert Fulton whose diving-boats so nearly fulfilled the conditions
necessary for practical submarine navigation. As America was at
peace at this time, and as her financial condition was at the lowest
ebb, Fulton transferred his skill and energy to Europe which was
then involved in the Napoleonic wars. Several attempts were made to
interest the French government in his invention, but although certain
commissions reported favorably on his ideas, nothing came of them for
a time. In 1800, however, Fulton succeeded in interesting Napoleon in
his scheme, and the following year he was given the opportunity of
building his first submarine boat, the _Nautilus_. This boat was cigar
shaped, about twenty-one feet long and seven feet in diameter, and made
of copper supported by iron ribs. When operating at the surface this
boat used a peculiarly shaped sail; but when submerged it was propelled
by a screw actuated by machinery turned by hand. In this boat, Fulton,
with three companions, descended to a depth of twenty-three feet and
remained submerged for twenty minutes; and at a depth of five or six
feet they are said to have remained submerged for six hours, air being
supplied by a copper vessel, probably containing oxygen or compressed
air.
The first experiment made in attempting actually to destroy a vessel
with the _Nautilus_, was successful, a small vessel being sunk.
Encouraged by this success Fulton proposed to build larger boats of
this same type capable of destroying the largest battle-ships. In
return he asked that a reward be paid him for each vessel destroyed,
the price of his diving boat reimbursed, and a patent be given himself
and the members of his crew, so that in case of capture they would
be treated as prisoners of war and not hanged as pirates. Strangely
enough this latter clause was the greatest stumbling-block, as the
proposed methods of destroying battle-ships by torpedoes was held in
such disrepute that the French government would not grant a patent
rating the crew of torpedo boats or submarine boats as legitimate
belligerents. In effect, their attitude was, that while a person was at
liberty to destroy an empire from the surface of the water, he would be
hanged as a criminal if he dived beneath the surface and destroyed a
boat.
Discouraged by this stand of the French government, Fulton removed to
England, where he succeeded in interesting the prime-minister, William
Pitt, in his novel boat. A commission was appointed consisting of a
number of prominent men, including Mr. Pitt, and Fulton was requested
to demonstrate what could be done in actual practice by his submarine.
On October 15, 1805, an old brig detailed for the purpose was destroyed
by Fulton by the explosion of a torpedo containing one hundred
and seventy pounds of powder. Yet in the face of this remarkable
demonstration the commission remained unfavorable to Fulton's scheme,
although Mr. Pitt to the last retained his faith in the possibilities
of such boats.
Recognizing that further attempts in England would be fruitless,
Fulton returned to the United States. Here, in 1810, Congress became
sufficiently interested to appropriate five thousand dollars to assist
him in his work, and as a final test of the boat he had built, the
naval authorities prepared the brig _Argus_ to resist an attack by
the submarine. This preparation consisted in surrounding her with
protecting booms of logs, supporting strong netting, and held a
distance from the hull by spars. In fact all possible means short of
actually building a wall about the _Argus_ were taken to defeat the
attack. It is probable that the brig, when her preparations for defense
were completed, would have been invulnerable even to a modern torpedo,
and it is not surprising, therefore, that Fulton's attack upon her
utterly failed.
Commenting upon this failure and the means taken by the authorities to
protect the _Argus_, Fulton significantly remarked that the very fact
that a war vessel was obliged to make use of such means to protect
herself against a system of attack then in its infancy, spoke volumes
for the possibilities of this method of attacking when it should be
more fully developed.
But although this failure to destroy the _Argus_ caused Congress to
withdraw its aid for future experiments in submarine warfare, Fulton
himself never lost faith in the importance of his work. Even after
his successful invention of the steamboat, for surface navigation, he
is said to have remarked that, while this invention was important, it
could in no wise compare with the revolutionary effects upon navigation
that would eventually be produced by submarine boats. And despite his
failure to convince the government of the possibilities of his diving
boats, he continued his experiments with them. How nearly he succeeded
in making a practical submarine was shown in the second war with
England that followed soon after.
In this war a "diving boat," supposed to have been one of Fulton's
submarines, made several attacks upon the British man-of-war
_Ramillies_ off New London, in the summer of 1813. In the first two
attempts the approach of the submarine was detected by the crew of
the man-of-war, who cut their cables, and stood out of the harbor as
quickly as possible. In the third attempt, the diving boat succeeded in
coming up in a position directly under the _Ramillies_, fastened itself
to the keel and made a hole in the planking large enough to receive the
screw which was to fasten the torpedo in place. In the act of fastening
it, however, this screw was broken off, and the attempt had to be
abandoned for the moment.
This attack created such a panic aboard the British boat, that she
did not return to the inner harbor but kept constantly in motion
outside. Not satisfied with this protection against such "dishonorable
attempts," the British commander took on board his vessel a hundred
prisoners, apprising the Americans of the fact, and assuring them that
a similar action would be taken by all the ships of the British fleet,
so that in case a vessel was torpedoed the American prisoners would be
blown up with her crew. This effectually frustrated Fulton's plans; for
when the fact became known in the United States, the Americans were
naturally as vigorous as the British in protesting against Fulton and
his boats.
Obviously the rule that "everything is fair in war" was not accepted
in practice a hundred years ago. Fulton's attempts were regarded as
the acts of a pirate, those of the British commander as perfectly
legitimate and honorable methods.
A SUCCESSFUL DIVING BOAT
From the time of Fulton to the outbreak of the American Civil War there
were few attempts at submarine navigation. On the opening of this war,
however, efforts were made to perfect diving boats; and these efforts
were so well directed that eventually one of these boats succeeded in
destroying the Federal boat _Housatonic_ in Charleston Harbor on the
night of February 17, 1864.
The submarine that accomplished this was one of the most remarkable
boats ever constructed. It was cigar shaped, about sixty feet long,
and carried a crew of nine men. It was submerged partly by means of
ballast tanks and partly by lateral fins. As a weapon it carried a spar
torpedo fastened to its blunt nose. It was propelled by hand-power,
eight of the nine members of the crew working on a crank which actuated
the propeller. The ninth man, crouching in the bow, steered the boat.
No reserve air was carried, and consequently the length of time the
boat could remain submerged was limited to a very few minutes. On
account of this, and because of its unfortunate career, it was aptly
called the "peripatetic coffin"; and it justified this name by sinking
five different times, drowning thirty-five out of forty of the members
of its different crews. Nevertheless it succeeded in destroying an
American war vessel, thus demonstrating that this feat is possible
under condition of actual warfare.
The submarines of the Civil War came to be known by the general name of
"Davids," and several of them of different types were built. The only
successful attack of any of these Davids, however, was the one which
destroyed the _Housatonic_. In his book, _The Naval History of the
Civil War_, Admiral Porter described this attack upon the _Housatonic_
as follows:--
"At about 8.45 P.M. the officer of the deck on board the unfortunate
vessel discovered something about one hundred yards away, moving along
the water. It came directly toward the ship, and within two minutes of
the time it was first sighted was alongside. The cable was slipped,
the engines backed, and all hands called to quarters. But it was too
late--the torpedo struck the _Housatonic_ just forward of the mainmast,
on the starboard side, in a line with the magazine. The man who steered
her knew where the vulnerable spots of the steamer were, and he did his
work well. When the explosion took place the ship trembled all over as
if by the shock of an earthquake, and seemed to be lifted out of the
water, and then sunk foremost, heeling to port as she went down.
"Her captain, Pickering, was stunned and somewhat bruised by the
concussion, and the order of the day was 'Sauve qui peut.' A boat
was despatched to the _Canandaigua_, not far off, and that vessel at
once responded to the request for help, and succeeded in rescuing the
greater part of the crew.
"Strange to say the David was not seen after the explosion, and
was supposed to have slipped away in the confusion; but when the
_Housatonic_ was inspected by divers, the torpedo-boat was found
sticking in the hole she had made, and all her crew were dead in her.
It was a reckless adventure these men had engaged in, and one in
which they could scarcely have hoped to succeed. They had tried it
once before inside the harbor, and some of the crew had been blown
overboard. How could they hope to succeed on the outside, where the sea
might be rough, when the speed of the David was not over five knots,
and when they might be driven out to sea! Reckless as it might be, it
was the most sublime patriotism, and showed the length to which men
could be urged on behalf of a cause for which they were willing to give
up their lives and all they held most dear."
RECENT SUBMARINES AND SUBMERSIBLES
After the Civil War several nations interested themselves in the
subject of submarines, and during the Franco-Prussian war in 1870-71,
France attempted the construction of such vessels, but without success.
Yet the possibility of producing these boats was becoming more apparent
every year by the improvements in electrical motors, gasoline engines,
compressed-air motors, and the automobile- or fish-torpedo--itself a
miniature submarine boat.
In America the progress made in submarine-boat construction has been
fully as great, if not greater, than in any other country. Undoubtedly
the foremost figure in this progress has been Mr. P. Holland; and his
efforts and successes are largely responsible for the present fleet of
submarine boats built already, or in the process of construction, as
well as for those of several foreign countries. Indeed, in the matter
of submarine inventions, only one country can be considered as rivaling
America, that nation being France, whose enthusiasm for submarine
navigation has been much greater than that of any other nation,
although in the matter of results she has not outstripped the United
States.
Mr. Holland's first submarine boat was built in 1875. It was called
a "diving canoe," being only sixteen feet in length and wide enough
to hold one man clothed in a diving-suit. Four years later, however,
Holland built a larger boat called the _Holland No. 3_ constructed
along similar lines to the most recent submarines. This was the first
buoyant submarine to be steered up and down by horizontal rudders
alone, and may be said to mark an epoch in submarine navigation. But
the No. 3 had many defects, and Mr. Holland continued to build and
improve new boats, until finally his ninth boat, which is the one
familiarly known as the _Holland_, represented a practical form of
submarine vessel. This boat was 53 feet 10 inches long, 10 feet 3
inches in diameter, had a displacement of 75 tons, and carried 10 tons
of water ballast. The gasoline engine which it used when running at the
surface propelled the boat at the rate of seven knots an hour, and it
could travel a distance of fifteen hundred miles at this rate of speed
with the amount of fuel carried. When submerged it could run a distance
of about fifty knots without coming to the surface.
In diving, the Holland type of boat takes in sufficient water ballast
to lower it to the surface of the water. The horizontal rudders are
then brought into use causing it to descend to the desired depth, and
keeping it at an approximately uniform distance from the surface while
running submerged. By this arrangement the boat can dive very quickly,
requiring only a matter of eight or ten seconds for reaching a depth of
thirty feet. Record plunges have been made in less time than this.
The armament of the Holland boat was originally designed to consist
of three tubes, two of which were for throwing aërial torpedoes and
shells, and the third for discharging Whitehead torpedoes. One of
these aërial guns was placed in the bow, and one in the stem; but
later the stern tube was abandoned. The bow gun was designed to
discharge projectiles a distance of about one mile, such projectiles
weighing something over two hundred pounds and carrying one hundred
pounds of gun-cotton. The tube for discharging the Whitehead torpedo
was practically the same as the submerged tubes in use at present on
battle-ships.
Although this _Holland_ is now the type of diving boat most familiar to
the majority of people, and the one in use in several navies, it should
not be understood that the Holland boats were the only successful
submarines constructed up to this time. France and Russia had produced
successful diving boats; and in America those invented by Simon Lake,
some of which are used for wrecking and salvage work as well as for
war purposes, have proved quite as practical as the Hollands. In recent
tests of these two types by the United States Government the Holland
boats showed themselves to be slightly superior to the Lake boats in
certain particulars, but the margin of superiority was a very narrow
one.
The boats of the "Octopus" type are strictly speaking "diving boats,"
while the Lake boats are of the "even-keel" type. These terms refer to
the method of submergence, the diving boats changing their horizontal
trim when submerging, while the even-keel boats retain their horizontal
trim, or nearly so.
The Lake boats have some features not usually embodied in other
submarines, since some of the boats are designed for purposes other
than warfare. Thus, they are equipped with wheels, or buffers, on which
they can roll along the bottom of the ocean or bay. In the bow is an
air-tight compartment with an opening in the bottom through which a
diver can emerge and work on wreckage, or laying and disconnecting
mines. These boats have also a safety device in the form of a
detachable keel weighing several tons. In case of accident, when it
might otherwise be impossible to rise to the surface, this keel can be
detached simply by pulling a lever, thus giving the boat sufficient
buoyancy to rise to the surface. This particular feature of the
detachable keel is not peculiar to the Lake boats alone, some of the
foreign submarines using a similar arrangement as a safeguard.
[Illustration: THE AMERICAN SUB-MARINE BOAT "CUTTLEFISH" IN DRY DOCK AT
THE BROOKLYN NAVY YARD.]
Technically speaking the name "submarine" is now used only as applying
to those boats that are operated solely by electric power, have
little buoyancy, and do very little running at the surface. The term
"submersible" is applied to a submarine boat, actuated by electricity
while submerged, but using gasoline motors for motive power while
running at the surface. These gasoline engines are used at the same
time for charging the storage batteries; so that the submersible is
a much more practical boat than the submarine, and at the same time
is quite as good a diver. Indeed, although many naval writers are
very careful to make a distinction in the use of these terms, there
seems little need of doing so, since only one type of boat--the
submersible--is now considered practical. But as the word submarine
is the older and more popular, it is used here to cover both classes
except in specific cases.
For several years there were two classes of submarines under
observation--those possessing no floatability when submerged, and
those having some reserve buoyancy. The advantage claimed for the
no-floatability class of boats is that, having no buoyancy, they are
kept more easily at a certain depth below the surface of the water
instead of tending to come to the surface constantly as in the case of
boats of the other type.
But in actual practice the theoretical possibilities of such boats have
not come up to the expectations of their advocates. For keeping the
boat at a uniform depth, the most universally accepted method is by
the use of horizontal rudders. The fact that the vertical direction of
a boat may be controlled by horizontal rudders, when her buoyancy is
small, has long since been established in submarine navigation; and
the simplicity of this method naturally helps its popularity. If there
were no shifting of weight in a submarine, or no wave disturbance,
it would not be difficult to set the rudders at such an angle that
the boat would travel for long distances at an approximately uniform
submergence, the depth of submergence being indicated by gauges acted
upon by the water pressure on the surface of the boat. And in actual
practice it is possible to do this at the present time, part of the
problem having been solved by automatic and other devices.
It should be remembered that many things enter into the disturbance of
the submarine's equilibrium. The movement of a member of the crew from
one point to another shifts the ballast; a certain amount of leakage of
water cannot be avoided, and the sudden discharge of a torpedo weighing
several hundred pounds from her bow tends to bring the boat quickly
to the surface if this lost weight is not compensated for quickly. By
various ingenious devices all these difficulties have been practically
overcome, most of them automatically.
But the great unsolved problem of submarine navigation--practically
the only one that now opposes a question mark to its great utility
in warfare--is that of steering with certainty of direction when
submerged. Once the submarine is under water it is in utter darkness as
far as seeing to steer is concerned; and what adds to the difficulty
is the fact that the compass cannot be relied upon, because of the
surrounding electrical apparatus. It would be possible, perhaps, to
construct a powerful electric lamp to throw a light some distance
ahead of the boat, but this would defeat the primary object of
submarine attack, as such a light would be seen by an enemy.
In still water, when the boat is running within a distance of ten
or fifteen feet of the surface, it is possible to steer with great
precision by the use of an optical tube or "periscope." This periscope
is a straight, hollow tube, connected with the steering compartment
in the submarine, and protruding above the water. In the upper end
are a mirror and lenses so arranged that the surrounding objects are
reflected downward through the tube, and show on a screen, or some
other device, so that the helmsman sees things of exactly the same size
that they would appear to the naked eye. The periscope is also fitted
with a telescope attachment which magnifies objects like the binoculars
used in surface navigation. On some recent submarines there are two
periscopes, a movable one for use of the commanding officer, and one
that looks straight ahead for the helmsman's use.
In still water the periscope works admirably, but it is seriously
interfered with even by small waves. It is so small and inconspicuous,
however, that it might enable a submarine to creep within torpedo range
even in daylight, and launch the torpedo with accuracy, as was proved
in 1908 when a fleet of submarines actually accomplished this feat in
an experimental test.
PRESENT STATUS OF SUBMARINE BOATS
To most people, one of the most surprising things in the Russo-Japanese
war was the fact that submarine boats played no part in it whatever.
There is only one possible conclusion to be drawn from this: the day of
the submarine as a determining factor in naval battles on the high seas
had not arrived.
The reason for the surprise of the generality of people in finding the
submarine was not as yet an entirely practical war engine, is due to
the enthusiastic misrepresentations of the daily press and magazines,
whose readers have been led to infer that the modern submarine boat
is so far perfected that it can do things under water almost as well
as boats on the surface. Nothing is farther from the truth. Under
ideal (and consequently unusual) conditions, the submarines, and
submersibles, have done, and can do, some remarkable things, such as
staying submerged for hours, diving to a depth of two hundred feet, and
running long distances. But these are only the first requisites of the
under-water fighting boat--simply the "creeping stage" of development.
The common impression that the submarine boat, such as the ones of the
Holland and Lake types, can go cruising about, fish-like, for hours,
watching for its prey in some mysterious manner without coming near the
surface, is a dream not yet realized.
If one will pause to consider that light is necessary to sight and that
one hundred feet of sea water makes almost as efficient an obstacle to
vision as a stone wall, it will be easy to understand why the submarine
is still struggling with difficulties that oppose its perfection. The
fanciful illustration seen so often of a submarine diving hundreds of
feet deep in the water, swimming about and finally coming up under the
keel of a battle ship and destroying it, are as yet the creations of
vivid imaginations. For submarine marksmen, like all others, require
a fairly clear view of the target--even such a huge target as a
battle-ship--to direct their shots with any degree of certainty.
The greatest problem now confronting the submarine navigator,
therefore, is that of seeing without being seen. At night, and at long
ranges, this is not difficult, as the little conning-tower, or tiny
periscope tube protruding above the waves, is not easily detected
even by strong searchlights, sharp eyes, and marine glasses. But long
ranges are of little use to the submarine; and there is always another
difficulty--the leviathan battle-ship does not lie still waiting to be
stabbed by its sword-fish enemy, but keeps moving about, twisting and
turning, at a rate of from fourteen to eighteen knots an hour, while
the submarine can only make about eleven knots when submerged. In a
stern chase, therefore, the submarine is one of the most harmless of
sea-monsters, in the open ocean. For harbor work, however, the case is
different. In some recent tests the submarine boats made eighty per
cent. in hits while attacking moving vessels in a harbor at night--a
far higher percentage than is usually made by surface torpedo boats
under the same circumstances.
At present the best solution of the problem of steering the partly
submerged submarine is offered by the use of a conning-tower elevated
five or six feet above the body of the submarine, which can be kept
just above the waves, and present an inconspicuous target. The early
Holland boats did not have this, although the American Lake boats have
had it from the first; but at the present time all boats are being so
made. At first these towers were made circular in form; but it was
found that towers of this shape made sufficient splash in passing
through the water to attract attention at a considerable distance on a
still night. This shape was abandoned, therefore, and a boat-shaped one
adopted.
With such a noiseless conning-tower the submersible can cruise about
on foggy nights, or when the waves are just high enough to make a
disturbance on the surface, running with the top of the conning-tower
open so as to secure good ventilation as long as possible, until the
enemy is nearly within striking distance. As the target is approached
the conning-tower must be closed, the protruding top sunk lower and
lower in the water, and finally completely submerged, nothing appearing
at the surface but the periscope tube just above the waves. With the
aid of this instrument the target may still be seen distinctly, but the
arc of vision is limited, and guessing the distance or rate of speed of
the target is very difficult. Nevertheless, by estimating the distance
before submerging, and knowing the rate of speed of his little craft,
the submarine gunner may still get his range and find his target.
If the waves are at all high, this is very difficult, as the water,
slopping over the periscope, obscures the vision for several seconds at
a time and is very distracting. But some experiments carried on during
the summer of 1908 show that, even in broad daylight, it is no easy
matter for a battle-ship to detect the approach of submarines until
well within torpedo range, even when an attack is expected.
In these experiments the United States cruiser "Yankee" in Buzzard's
Bay was attacked by five submarines of the most recent type. The
"Yankee" remained stationary expecting the attack, but to offset this
disadvantage the crew was fully aware of the exact time that the attack
was to be made. Indeed the officers of the cruiser had watched the
submarines steam away until they disappeared. When twenty miles from
the "Yankee" the five submarines submerged and headed for the cruiser,
making observations at intervals by means of the periscope.
The day was perfectly clear, and all on board the "Yankee" were keenly
watching for the expected submarines. Yet the first intimation they had
of the proximity of the diving boats was the striking of five torpedoes
against the cruiser's hull. Each submarine had scored a bull's-eye.
Not content with this success, the submarines repeated the attack from
a nearer point, again scoring five hits before their presence was
detected.
One great obstacle to successful submarine navigation on an extended
scale is the difficulty of keeping a supply of air not only for the use
of the crew, but for the engines. Any really powerful engine, either
steam or gas, consumes an enormous amount of air. This is not true, of
course, of the storage batteries which furnish the power for running
while submerged, but these, at best, are but feeble generators of
energy, although Edison's recent improvements may materially improve
their power. If gasoline engines could be used during submergence a
far greater speed would be acquired; but this is out of the question,
as such engines would consume the air supply of the little boat far too
rapidly. The compromise, now adopted universally, is to use gasoline
motors while running at the surface or partly submerged, when the
conning-tower is open, utilizing part of their energy meanwhile to
charge the storage batteries.
It is evident, therefore, that no great speed can be expected of the
submarine in its present state; and in point of fact the largest type
is able to develop only about ten or eleven knots when submerged, and
fifteen while at the surface--far below the speed of any other type
of war vessel. But the experimental attacks upon the "Yankee" prove
that they are dangerous fighting craft, and a recent voyage by a
flotilla of Italian submersibles shows that such boats are no longer
harbor-locked vessels. In 1908 the Italian flotilla in question made
a voyage from Venice to Spezia, a distance of thirteen hundred miles,
without assistance from auxiliary boats. About the same time a British
submarine flotilla, on a three-hundred mile trip, remained submerged
for forty consecutive hours. The depth of the submergence in this case
was only a few feet, but great depths may be reached with relative
safety. In one test a Lake boat carrying her crew sank to a depth of
one hundred and thirty-eight feet, returning to the surface in a few
minutes. At another time the "Octopus," without her crew, was lowered
to a depth of two hundred and five feet, sustaining a pressure of
fifteen thousand tons, without injury.
[Illustration: A FLEET OF BRITISH SUB-MARINES MANŒUVERING AT THE
SURFACE.]
Such performances as these are thought-provocative, to say the least.
Submarine boats that can hit the target without being detected, go on
cruises unattended for more than a thousand miles, and remain submerged
for more than a day and a half, must be classed as efficient engines of
warfare.
Since the submersible is designed to spend most of its time on the
surface of the water like an ordinary boat, it must have considerable
buoyancy, but it must also have some means of getting rid of this
buoyancy quickly when submergence is necessary. The submarine proper
has only from five to eight per cent. buoyancy, while some of the
submersibles have twenty-five per cent. or more. With such boats of
the ordinary size some fifty tons of water must be admitted before
bringing them to a condition in which they can be submerged; but this
can be done very quickly. One of the submarines of the U. S. fleet in
an actual test filled her ballast tanks and dived to a depth of twenty
feet in four minutes and twenty seconds.
It is not impossible that the recent triumphs in aërial navigation may
have an important bearing on the use of submarines in future wars. It
is well known that large objects when submerged even to a considerable
depth are discernible from a height in the air directly above them.
It is quite possible, therefore, that swift aeroplanes circling about
a fleet of war vessels might be able to detect submarine boats when
these boats were near enough the surface to use their periscopes. If
so it might be possible for the aeroplanes to drop torpedoes upon the
submerged boats without danger to themselves. Or if the aeroplanes
carried no effective weapons, they could at least act in the capacity
of scouts and warn their battleship consorts of the presence of the
submarine. Of course, this would be possible only in daylight, the
airships giving no protection against night attacks.
IV
THE STEAM LOCOMOTIVE
Modern railroads are the outcome of the invention of the locomotive;
yet the invention of the practical locomotive was the outcome of iron
railroads which had been in existence for half a century. These iron
railroads were a development from wooden predecessors, which were the
direct descendants of the smooth roadways of the Greeks and Romans.
Indeed it is quite reasonable to suppose that the ancients may have
been familiar with the use of parallel rails with grooved or flanged
wheels to fit them; but if so there seems to be no definite record of
the fact, and our knowledge of true railroads goes back only to the
seventeenth century.
As early as 1630, it is recorded that a road built of parallel rails of
wood upon which cars were run was used in a coal-mine near Newcastle,
England; and there is no reason to suppose that this road was a novelty
at the time. Half a century later there was a railroad in operation
near the river Tyne which has been described by Roger North as being
made of "rails of timber placed end to end and exactly straight, and in
two parallel lines to each other. On these rails bulky cars were made
to run on four rollers fitting the rails, whereby the carriage was
made so easy that one horse would draw four or five chaldrons of coal
to a load."
At this time the use of iron rails had not been thought of, or at least
had not been tried, probably from the fact that iron was then very
expensive. Even the wooden rails in use, and the wheels that ran upon
them, were of no fixed pattern. Some of these rails were in the form
of depressed grooves into which an ordinary wheel fitted. But these
were very unsatisfactory because they became filled so easily with dirt
and other obstructions, and a more common type was a rail raised a few
inches above the ground like a molding, a grooved wheel running on the
surface.
Such rails were short lived, splitting and wearing away quickly, and
being easily injured by other vehicles. But they were, on the whole,
more satisfactory than t
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