an Austrian naval officer; but it took rather the form of a small vessel
containing within itself some propelling power by which it could move
along the surface of the water, its course being directed by ropes or
guiding lines from the shore or from a ship. The fore part of the little
vessel was to hold an explosive, to be fired automatically by the
self-propelled torpedo coming into contact with the side of the hostile
vessel. The propelling power, as first suggested, was clockwork, if that
could be made efficient, or steam as an alternative. The Austrian
authorities, however, considered that it would be impracticable to
direct the course of the torpedo in the manner proposed, and that there
were also great objections to each of the methods of obtaining motive
power. The assistance of a thoroughly competent and skilful mechanician
was then sought, and Mr. Whitehead, at that time the director of an
engineering establishment at Fiume, devoted himself to solving the
problem of devising a torpedo which should be able to travel beneath the
surface of the water, and, when once started, should require no external
guidance to keep it on its proper course. After some years of
experimental labours, Mr. Whitehead produced the first form of the
weapon with which his name is associated, but to this he has since added
from time to time many ingenious improvements. A committee of experts
having been appointed by the Austrian Government to test the
capabilities of the new invention, it was made the subject of a long
series of trials, after which the committee recommended its immediate
adoption in the Austrian navy. The earlier form of the Whitehead torpedo
had, however, the defect already mentioned, of being sometimes very
erratic in its course; its speed was small (6 knots) compared with that
of the more recent patterns (30 knots), and its range of travel
proportionately less. The British Admiralty having invited Mr. Whitehead
to visit England with some specimens of his invention, a committee was
appointed to make complete trials of the capabilities of two weapons he
had brought with him. Although by this time great improvements had been
made on the original design, and in particular, Mr. Whitehead had almost
completely overcome the difficulty of keeping the torpedo at a uniform
depth during its course, by means of delicate adjustments in what we may
call the steering chamber (to be presently mentioned), much remained to
be accomplished before the weapon attained the perfection of the modern
patterns. Indeed, the inventor may be said to have from time to time
redesigned his contrivances, as when in 1876 the speed was increased to
18 knots, and again in 1884 more powerful engines brought up the speed
to 24 knots. Further improvements have been made by Mr. Whitehead, who
designed a new form of the weapon in 1889, and some of the more recent
patterns can now show a speed of 30 knots or more. The committee
appointed by the Admiralty to conduct experiments with the first pair of
torpedoes brought to England, after having tested them in various ways
for a period extending over six months, reported that they believed that
“any maritime nation failing to provide itself with submarine locomotive
torpedoes, would be neglecting a great source of power, both for offence
and defence.” Upon this recommendation the Admiralty immediately
purchased from Mr. Whitehead for £15,000 the secret of the internal
mechanism of his invention and the rights of manufacturing it. The
self-adjusting apparatus within the steering chamber, by means of which
the torpedo was kept at its due depth, was then a jealously-guarded
secret; but when the arrangement with Mr. Whitehead was effected, the
Government immediately set about the manufacture of these torpedoes on a
large scale. The artificers employed in making the Whitehead torpedoes
were now numerous, and the internal structure of these weapons could not
advantageously be altogether concealed from those who had to handle them
on board of the ships, so that it inevitably happened that some details
of their construction leaked out, and came into the possession of other
powers, whereupon all the maritime states followed the example of Great
Britain by providing their navies with Whitehead or some such form of
locomotive torpedo. It is no part of our plan to enter into the
mechanical _minutiæ_ of the Whitehead torpedo. We may, however, give the
reader such an idea of the external appearance and internal arrangement
of the Whitehead torpedo as will enable him to appreciate to some extent
the ingenuity and skill that have been brought to bear upon its
construction.
There are in existence many different patterns of the
weapon—twenty-four, it is said—and this is what might be expected from
the fact of its being produced at several different manufactories, each
striving to effect whatever improvements its resources will supply. Some
torpedoes have been made at Fiume, very many at Mr. Whitehead’s works at
Portland, as also at the Government establishment at Woolwich, while
private enterprise in this direction is encouraged by contracts with
some private firms, such as that of Messrs. Greenwood & Bately at Leeds.
The greatest diameter of the large torpedo is 18 inches, but in some it
is rather more, in others 14 inches or 16 inches; and the length may
vary between 14 feet and 19 feet. Many of our Whitehead torpedoes are
made of polished steel, but in the later patterns phosphor-bronze is
partly made use of, as being not liable to corrode. The interior of the
torpedo is divided by transverse partitions into five distinct
compartments. The foremost of these, called the “head,” contains the
explosive charge when the weapon is ready for use in actual warfare.
This section, which may occupy about one-sixth of the total length, is
an air-tight case made of phosphor-bronze, one-sixteenth of an inch
thick, and it is kept permanently charged with slabs of wet gun-cotton,
which may amount to 200 pounds weight in all, and is ready to be
attached by a screw and bayonet joint to the body of the torpedo; but
this is done only at the time immediately before it is required for its
destructive employment. Its place at other times, as when the torpedo is
used for drill practice, and to test its running powers, is occupied by
a dummy head of steel, of exactly the same shape and size, and packed
with wood in such a manner that its weight and centre of gravity are
like those of the explosive head when the latter is ready for action.
The wet gun-cotton requires a _detonative_ explosive of dry material
close to it, in order to determine its own detonation. The explosive
heads of the Whitehead are not fitted with the pistol and priming tube
until all is ready for the discharge of the weapon, as this would render
the handling of the torpedo highly dangerous. This priming apparatus is
merely a metallic tube that slips into a corresponding hollow in the
explosive head so far as to reach well within the wet gun-cotton charge,
although still separated from the latter by a metal casing. The
posterior extremity of the priming tube contains a few ounces of dry
gun-cotton, and just in front of this is a copper cap containing some
fulminate of mercury, which readily explodes when struck by the point of
a steel rod, occupying the centre of the tube and projecting a short
distance out at the “nose” of the torpedo, so as to be driven inwards by
the impact of the latter on a ship’s side. The explosion of the
fulminate causes the detonation of the dry gun-cotton at the bottom of
the priming tube, and this is taken up by the whole mass of the
explosive with destructive effect. The danger of premature or accidental
explosion by anything coming in contact with the projecting striker is
obviated by several checks which prevent any chance blow driving the rod
home against the fulminate charge. The anterior projecting end of the
rod has a screw thread worked upon it, and on this turns freely a nut
provided with wings like a small fan, revolving in such a manner that as
the torpedo is moved through the water, the nut is spun off, and the
striker is free to be driven back, except in so far as it is still
retained by a small copper pin, the breaking of which requires a
considerable blow. Again, the little fan above mentioned cannot begin to
spin off the rod until another pin or wedge has been withdrawn, which
operation is performed just before launching the weapon.
Immediately behind the exploding head of the torpedo is the air-chamber,
which occupies a considerable space in the length, _i.e._, about
one-third of the whole. This part is made of the toughest steel, nearly
⅓ of an inch thick, and contains the power actuating the motor, in the
form of air forced into it by powerful pumps on board the ship, until
the pressure reaches the enormous amount of 1,300 lbs. or more on the
square inch, or, at least, this is what is made use of in the newer
patterns when charged for action. In the largest size of the weapon the
weight of air injected may be more than 60 lbs., and, of course,
considerably detracts from the buoyancy of this part.
Behind the air-chamber comes another much shorter compartment we have
called the “steering chamber,” in which are contained the most ingenious
and delicate parts of the apparatus, namely, the mechanism by which this
extraordinary artificial fish adjusts itself, after the manner of a
living thing, to the required conditions. Among other contrivances, it
contains several valves controlling the action of the compressed air on
the engines, etc. The enormous pressure to which the air-chamber is
charged, if allowed to act unchecked, would give at first a power almost
sufficient to shatter the machinery, and, in order to prevent this, a
“reducing valve” is interposed so that only a moderate and uniform
pressure of air is allowed to act upon the engines. Then there is the
“starting valve” by which the air is admitted or cut off from the
engines, and still another valve which is contrived to delay the action
of the compressed air for the short interval during which the torpedo is
passing from the discharging tube until it enters the water. For during
this interval the propellers not having to act against the water, but
only against the resistance of the atmosphere, would be whirled round at
an enormous speed, and the machinery would sustain such shocks and
strains as might endanger the whole apparatus. It is to prevent this
that the “delay action valve” is provided.
The automatic apparatus by which the torpedo’s course is regulated is a
very remarkable part of the invention, and it admits of the nicest
adjustments. This was the crown of Mr. Whitehead’s ingenuity, but the
details were, by an arrangement between the government and the inventor,
not to be made public, though necessarily communicated to certain
officers in the service, and known to the chief artisans employed in
their fabrication. These persons are all, we believe, required to give
pledges not to divulge the arrangement of particular parts. But such
details could scarcely be made intelligible, even should they be
interesting, to the general reader. The principles upon which the
controlling apparatus are arranged may, however, be comprehended without
difficulty.
The tail of the torpedo is provided with two rudders, one in its central
vertical plane, and the other in its central horizontal plane. Their
action in directing the torpedo’s course is exactly that which the tail
supplies to a fish, or the rudder to a boat. Suppose that while the
torpedo is passing through the water the vertical rudder is by any means
turned towards one side, the course of the metallic fish will be
diverted towards that side; or again, a turning upwards of the
horizontal rudder would have the effect of directing the nose towards
the surface, and would make the torpedo rise, and so on. Now the
positions of the horizontal rudder are regulated from the “steering
chamber,” in which a heavy weight is suspended like a pendulum, so as to
be capable of swinging fore and aft. This pendulous weight actuates the
horizontal rudder through a system of rods and levers, so that when it
hangs vertically the horizontal rudder is level, but if from any cause
the nose of the torpedo were directed downwards, the pendulous weight
would come to a more forward position in the steering chamber, and would
raise the rudder, and thus turn the nose towards the surface until the
original horizontal position were regained. In the contrary case, of
course, the reverse action would take place. But the torpedo, while
preserving a horizontal position, might tend to sink to too great a
depth, or rise too near the surface, and this is prevented by another
adjustment, namely, a piston receiving the pressure of the water, which,
on the other side, is opposed by a spring. If the torpedo sinks a little
the pressure increases, the piston, which moves with perfect freedom
without allowing water to pass in, is forced inwards, and its movement
is communicated to the same levers that connect the pendulous weight
with the horizontal rudder, the latter is raised, and then the nose of
the torpedo is directed upwards, and it consequently approaches the
surface again. In the contrary case the spring, relieved from some of
the external pressure, operates the levers in the other direction.
The compartment immediately behind the “steering chamber” contains the
engines which are of the Brotherhood type, provided with _three_ single
acting cylinders. The three-fold throw prevents any possibility of the
engine getting on a “dead point.” Though this compartment is the
shortest in the torpedo, the engines in the larger sizes are capable of
indicating as much as thirty horse power. It has for simplicity been
stated above that the pendulous weight and the balanced piston act by
means of rods on the horizontal rudder; this was so in the early
patterns of the torpedo, but it was soon found that they did not do so
with sufficient steadiness and promptitude, and the force they could
apply was in the larger and swifter forms quite ineffective. Nowadays
the engine compartment always contains a little piece of apparatus which
is an arrangement of cylinder and piston, upon which the compressed air
acts in one or the other direction according to the way its slide-valve
is moved. It is this slide-valve that the rods from the “steering
chamber” move, and allow the force of the compressed air to turn the
rudder up or down. This auxiliary apparatus has the same relation to the
torpedo rudder that the steam-steering apparatus of a large vessel has
to its rudder. Although it is only about a few inches long, its power
and delicacy are such that the pressure of half an ounce on its slide
admits to its piston a force equal to 160 lbs., and its introduction has
given the torpedo the power of steadily steering itself.
Behind the engine compartment, but completely shut off from it, is
another almost empty division occupying a considerable part of the
length of the torpedo, and known as the “buoyancy chamber.” But it
contains, attached to the bottom of it, a certain amount of ballasting,
so adjusted to balance the weights of the other parts that the whole
floats horizontally, and at the same time preserving the tube in one
vertical position as regards its transverse diameter, _i.e._, so that
the horizontal rudder is always horizontal. The shaft from the engine
passes through this compartment, as also the rod from the small motor
that moves the horizontal rudder. These, of course, pass through
water-tight bearings.
At the tail of the torpedo, behind the rudders, are _two_ three-bladed
screw propellers, of which the anterior one is mounted on a tubular
shaft having a common axis with the other, but made to revolve in the
opposite direction by means of a bevel wheel mounted on each independent
shaft, with a third such wheel connecting them. The object of the double
screw is to obviate “slip,” that is, ineffective motion of the blades
through the water, and by this means the full power of the engines can
be developed; while any tendency to _deviation_ to right or left, due to
the rotation, is reduced to a minimum. We have spoken of one horizontal
and one vertical rudder, although externally there appear to be two of
each kind, right and left, above and below, on the tail of the torpedo.
These pairs, however, are so connected as to be always in the same
respective planes. The controlling mechanism acting in two different
ways on the horizontal rudder has been already indicated, but nothing
has yet been said about the vertical rudder. It is not moveable by
anything within the torpedo, but is commonly fixed by clamping screws in
or about the same vertical plane as the axis of the torpedo, and it
performs the same function as a kind of back fin, which, in the earlier
forms, extended nearly the whole length of the tube; and that is
obviating any tendency of the torpedo to roll about its axis. The
vertical rudder can also be fixed at a considerable inclination to the
axis should occasion require, and the effect of that would be to cause
the torpedo to pursue a circular course of greater or less radius,
according to the less or greater degree of inclination. Very rarely,
however, would this be required, and the vertical rudder may be
considered as fixed in the axial plane, or having such slight
inclination as may, on trial, have been found necessary to counteract
any tendency to lateral deviation.
There are several different methods for discharging the Whitehead
torpedoes from ships. They may be sent from a tube below the water-line,
but the arrangements for that purpose are complicated and difficult to
manage, while, on the other hand, the launch of the weapon is not
perceived by the enemy, and it is at the same time out of the reach of
any blow from a hostile missile while yet in its discharging tube. More
commonly the discharging tube is arranged above the water-level. On
regular torpedo boats, the tubes are sometimes mounted on pairs upon a
revolving table, provided with many nice adjustments, and even the
single above-water torpedo tube, as used between decks, is an apparatus
having somewhat complicated appliances. The torpedo is expelled from the
tube now preferably by a small charge of _cordite_. But in the Royal
Navy no fewer than some twenty different patterns of torpedo tubes have
been in use for the various sizes of torpedoes. In some of these,
compressed air, in others gunpowder or _cordite_, in others, again,
mechanical impulse propels the torpedo into its element. It would
obviously be impossible within our limits to enter into details of these
various constructions, or to attempt descriptions of _all_ the ingenious
contrivances applied to the torpedo itself, or to give an account of the
means of defence against mines and torpedoes, this last being a matter
belonging to naval tactics. The adoption of the torpedo as a naval
weapon has given rise to special types of boats adapted for its
employment, and these again have required other boats to destroy them
(“torpedo-boat destroyers” or “catchers”). Light draught and high speed
were desired in these last; but in many cases the intended speed was
inferior to that of the torpedo boats that were to be caught.
The following particulars about the British torpedo-boat destroyer
_Daring_ may be compared with those given of the cruiser _Majestic_. The
_Daring_ is 185 feet long, 7 broad, and she draws only 7 feet of water.
Her speed is about 28½ knots per hour, with a steam pressure in the
boilers of 200 lbs. per square inch, and an air pressure in the
stoke-holds equivalent to 3 inches of water (forced draught.)
The importance attached to the prospective use in war of the automobile
torpedo may be shown by the fact that at the end of 1890 the number of
torpedo boats built or laid down for England was 206, and for France
210, while other nations followed with numbers proportionate to their
means. Forty “torpedo-boat destroyers” were in building for the British
Navy towards the close of the year 1896, and now (March, 1897) it is
announced that the number of torpedo boats and torpedo-boat destroyers
in the French Navy is to be increased by 175.
[Illustration]
[Illustration:
FIG. 122.—_M. Ferdinand de Lesseps._
]
SHIP CANALS.
Artificial canals are amongst the oldest of inventions, for, centuries
ago, they have been constructed, even of very large dimensions, in
various parts of the world. There is in China, for instance, a great
canal, 900 miles in length and 200 feet broad, which is supposed to have
been made 800 years ago. The advantages of canals did not escape the
attention of the Egyptians, Greeks and Romans. We read of very early
attempts to cut through isthmuses, in order to form a water
communication between regions where other carriage would be long and
difficult. It appears to be admitted that canals connecting the Red Sea
with the Mediterranean existed some centuries before the Christian era,
and to cut the Isthmus of Corinth by a waterway was a cherished project
with several Roman Emperors, and now it appears that in this nineteenth
century this project will shortly be realized. But as the canal-lock is
but a comparatively modern invention, dating only from the fourteenth
century, and first used in Holland, all the canals anterior to that
period had to be designed as level cuts, a restriction which greatly
increased the difficulties of the problem. Canals were in use in various
parts of Europe, particularly in Holland and France, long before any
were constructed in England, as, for example, the Languedoc Canal,
which, by a cut of 150 miles, connects the Bay of Biscay with the
Mediterranean. It is 60 feet broad, and attains, at its highest level,
an elevation of 600 feet above the sea. The canal system in England was
first introduced in the middle of the eighteenth century, and soon
afterwards, the Duke of Bridgewater engaged the famous Brindley to
construct a canal, connecting his collieries at Worsley with Manchester,
about seven miles distant, and afterwards extended his scheme, so as to
open up a more direct water communication between Manchester and
Liverpool. Before the making of this canal, the cost of the carriage of
goods between these towns had been forty shillings per ton by land, and
twelve shillings by water. After that, they were conveyed with
regularity for six shillings per ton. The system was soon extended, so
as to connect the Trent with the Mersey, and the boldness of both the
projectors and their engineer in carrying out this scheme is memorable
in the history of such undertakings. Brindley was equal to the task of
coping with the difficulty of carrying his canal over what had hitherto
been supposed an insuperable obstacle, for he pierced Harecastle Hill
with a tunnel more than a mile and a half in length—a then unheard of
piece of engineering—to say nothing of several shorter tunnels, many
aqueducts, and scores of locks. The Duke of Bridgewater, who at one
period had been unable to raise £500 on his own bond for the prosecution
of his scheme, died in 1803, in receipt of a princely income from the
profits of his useful undertaking. For its creation, he had, however,
denied himself the present enjoyments of his patrimonial revenue, by
reducing his expenses at one period to the modest sum of £400 per annum.
Before his death, the Duke, for taxation purposes, estimated his income
at £110,000 per annum. Before the railway system was fully established a
network of canals had united the most populous places in England, the
total length of the waterways being not much less than two thousand
miles. With the rise of railways the importance of canals as channels
for the conveyance of merchandise declined. But, nevertheless, in
consequence of the continued increase of traffic and the great cheapness
with which goods can be carried by water, canals are often able to
compete with railways in the carriage of bulky or heavy goods when speed
of transit is not an object. The English canals have, therefore, never
been disused or abandoned, notwithstanding the ubiquitous ramifications
of the railway lines. Nay, the value of the Bridgewater Canal system,
about to be superseded so far as concerns the communication between
Liverpool and Manchester by the greater scheme we have presently to
describe, is such that £1,710,000 is now required for its purchase; and
that is the value in spite of four lines of railway connecting those
great towns, and all competing for the carriage of goods. In these
canals, designed for inland communication only, the navigation is
confined to boats or barges of very insignificant dimensions compared
with the sea-going ships that some great modern canals are constructed
to receive.
To the present century belongs the famous “Caledonian Canal,” as the
waterway is often called that extends in a straight line for more than
60 miles across Scotland, in north-east and south-west directions. The
canal work here was commenced in 1802, under the direction of Telford,
and though it was opened for traffic in 1822, the work as it now exists
was not completed until 1847. But the length of the actual canal
construction in this case did not much exceed 23 miles, for a natural
waterway, navigable for ships of any burden, is formed by the series of
narrow lakes that fill what is called the “Great Glen of the Highlands.”
This glen has many of the characteristics of a great artificial ditch:
its highest point is only 90 feet above the tide level in Loch Linnhe; a
circumstance not a little remarkable in so mountainous a country. What
is also remarkable is the great depth of these lakes, which in some
places exceeds 900 feet. The banks also are generally very steep, and
indeed at one time it was impracticable to pass along the shores of Loch
Ness, the longest of the lakes. But there are now good roads along both
banks. Although the ground traversed by the artificial channels of the
Caledonian Canal is chiefly alluvial, the cost of the undertaking proved
to be great, amounting, it is said, to about one and a quarter million
pounds sterling. Indeed, had it not been for the introduction of steam
navigation before the completion of the work, and the consequent
increase and facility of water conveyance, it is doubtful whether the
utility of this canal would have been commensurate with its cost, or its
receipts have made any profit for its promoters. By the Caledonian Canal
large steamers and other vessels may pass from sea to sea, and in the
summer time the steamers that traverse it are crowded with tourists
attracted by the magnificent scenery it presents throughout the greater
part of its length.
But whatever had previously been done in canal construction was
surpassed in enterprise and importance by Lesseps’ great work in Egypt.
_THE SUEZ CANAL._