HOW WAR INVENTIONS GROW
The inventor of one of the devices described later on in this book
modestly claims that he did not invent it but it invented itself. What
he means is that he worked step by step, from simple beginnings, each
step when complete suggesting the next. To put it another way, many
inventions grow in the inventor's mind, sometimes from unpromising
beginnings, the most unlikely start often resulting in the most
successful ending.
Who has not heard of the "tanks" which made such a name for themselves
when they suddenly appeared in Northern France? The British
Commander-in-Chief simply mentioned that a new type of armoured car had
come into use with good results, but the newspaper men set the whole
non-Teutonic world laughing with droll stories of huge monsters
suggestive of prehistoric animals which suddenly began to crawl through
the slime and mud of the battle-field, pouring death and destruction
upon the astounded Germans.
How they came to be called tanks no one seems to know clearly but that
is how they will be known for all time. It has been suggested that they
were so named because tank is one of the things which they certainly
are not, the intention being thereby to add to the mystification of the
enemy. That is by the way, however, for we are more concerned with the
things than with their name.
Their precise origin is wrapped in mystery but we have it on excellent
authority that they grew out of the peaceful "tractor," originally
intended to drag a plough to and fro across a field in the service of
the farmer. An illustration of one of these interesting machines will be
seen in this book which will well repay a little study.
It consists of a steel frame or platform upon which is mounted a
four-cylinder petrol engine with a reservoir above to carry the supply
of fuel and with a radiator in front to cool the water which keeps the
engine from becoming too hot. Towards the back of the vehicle is what is
called by engineers a worm-gear, the function of which is to reduce the
one thousand revolutions per minute of the engine to somewhere near the
slow speed required of the wheels of the tractor.
This worm-gear is simply a wheel with suitable teeth on its edge in
conjunction with a screw so made that its thread can engage comfortably
with the teeth. This latter, because of the wriggling appearance which
it presents when it is revolving is called a worm, which name it gives
to the whole apparatus. Both wheel and worm are mounted in bearings
which form part of a case enclosing the whole so that dirt is excluded
while, the case being filled with oil, ample lubrication is assured.
The shafts of both wheel and worm emerge through holes in the case.
It will easily be seen that each single turn of the worm will propel the
wheel one tooth, so that if the wheel have fifty teeth, for example, the
worm will turn fifty times to the wheel's once. Thus a great reduction
in speed is attainable with this device and what is equally valuable, a
great increase of power also results. Thus a small engine, working at a
high speed, is able by means such as this to pull very heavy loads at a
slow speed.
It is evident, however, that the reduction necessary in this case cannot
be attained even by a worm-gear, for there are other wheels visible
which show that ordinary tooth gearing is also employed to reduce the
speed even further before it is applied to driving the tractor along.
Practically all the other gear which we see in the picture, above the
platform, consists of the controlling apparatus.
The object with a screw-like appearance just behind the engine is not
really a screw but is a flexible coupling joining the engine to the
worm-gear, its "flexibility" enabling the two to work sweetly together
even though by chance they may get just a little out of line with each
other.
But by far the most interesting part of the machine is that which is
underneath the frame. At one end we see a pair of ordinary-looking
wheels and between them the gear for swinging them to right or left for
steering purposes, but even they are somewhat unusual, since they will
be seen to have flanges or rims round the edge for the purpose of biting
into the earth, so that they may be able to guide the machine the
better in soft ground.
The back wheels, however, are quite peculiar, for there is a pair on
each side and round each pair is a chain somewhat after the fashion of a
huge bicycle chain. The links of this chain are made of tough steel and
they are two feet wide, so that each chain forms a broad track upon
which the machine moves. The links of this track-chain will be seen to
be tooth-shaped so that they grip or bite deeply into the yielding
ground. The teeth, moreover, are shaped like those of a saw and they are
so placed as best to help the tractor forward.
Between the two chain-wheels will be noticed a row of smaller wheels and
it is these which largely support the weight of the machine, the chains
forming tracks upon which they run.
The wheels actually turned by the power of the engine are the
chain-wheels, and their action is such as to keep on laying down and
then taking up again two broad firm tracks along which, at the same
time, they keep propelling the other wheels which carry the weight
above. The effect, really, is just as if the machine had a pair of
driving wheels two feet wide and of enormous diameter, of such diameter,
in fact, that the part in contact with the ground is almost flat. Thus
there is always a broad bearing surface to prevent sinking in soft
earth, while the tooth-like shape of the links gives a firm hold even
under very adverse conditions.
This form of construction has been used for some few years now under the
name of "caterpillar" or "centipede" traction. A glance at the picture
will explain those names, particularly if the chain-driven part of the
vehicle be imagined to be a little longer than it is in the particular
machine shown.
The idea of armouring a vehicle with bullet-proof plates is also a
fairly old conception. Armoured trains were used again and again during
the South African War, and armoured motor-cars became familiar to most
people. In the case of cars, however, the armour could only be very
light and the guns carried were limited practically to a single
machine-gun and some rifles. Moreover, the operations of a car are very
largely confined to such places as are blessed with good roads or smooth
plains. An armoured car of the older type would have cut a poor figure
amid the shell-holes and mine-craters of Northern France. It would have
had to keep to the roads and so it was little used.
But the idea of an armoured vehicle was good and a good idea is never
entirely lost. Sooner or later some genius puts it to good use. Thus the
idea of an armoured vehicle came to be associated with the idea
represented in the centipede tractor and the result was the tank.
Why not armour a large centipede, said someone? Make it very big and
strong. It will trample down the barb-wire entanglements as if they were
grass. If made long enough and rightly balanced it will pass over the
trenches like a moving bridge. Nothing but a direct hit from a heavy gun
will do it much harm. For, observe, the mechanism can be entirely
covered up, all the vital parts can be well protected, and the chain
tracks can be so strong as to be almost undamageable.
[Illustration: _By permission of_ _Messrs. Foster and Co._
THE PARENT OF THE TANK.
Here we see an innocent agricultural tractor with caterpillar hind
wheels. It is out of such a machine that the idea of the formidable tank
was evolved.]
Thus we get a glimpse of the growth of this simple peaceful agricultural
machine into one of the most striking mechanical achievements of the
Great War.
Another thing which seems to have grown more or less of itself is the
bomb or grenade. Before the time of modern accurate fire-arms
hand-grenades were quite a recognized weapon. The "Grenadier" Guards owe
their title to this fact and carry the design of a bursting grenade upon
their uniforms. Yet until a few years ago everyone thought that such
things were done with for ever: that with modern rifles soldiers would
seldom get near enough together to use grenades and that if they did the
bayonet would be the weapon to be used.
When, however, the Germans were driven back at the battle of the Marne
and found themselves compelled to entrench in order to avoid further
disaster, it soon became evident that neither rifle nor bayonet nor both
together entirely filled the needs of the infantryman.
Since the Allies were not powerful enough to drive the Germans from
their trenches forthwith, they, too, had to entrench. Gradually the
trenches drew nearer and nearer together and at the same time skill in
entrenching increased. Thus a time soon arrived when both rifle and
bayonet were largely useless for purposes of offence. Then the
hand-grenade came into its own again, for the men could throw it from
the depths of their own trench high into the air in the hope that it
would fall into the trenches of the enemy. The call for these quickly
produced the supply. There is little need to describe them here, for who
among us has not intimate friends who used them again and again? This
much may be said, however. They were little hollow balls of cast iron,
sometimes chequered so that when they burst they flew into many
fragments. Inside was a charge of explosive with a suitable fuse or
firing mechanism. Some were fixed to the end of a stick for convenience
in throwing, while others were simply handled like a cricket-ball.
They serve to show us, however, how an old idea may under fresh
conditions be revived into what is practically a new invention.
Another example of the same sort is the revival of chain mail. Who, but
a few years ago, would have thought it possible that modern soldiers
would go to battle sheathed in shirts consisting of little metal plates
cunningly connected by wire links and so overlapping each other as to
form a perfect shield for all the more vital parts of the body? To what
extent these were worn I do not know, for the British soldier is a very
shy fellow in some ways and there are few who would not be a trifle
ashamed to let their comrades see them thus garbed. They would feel that
it was a confession of fear, and however afraid an Englishman may be he
will never admit it. He is really a pious fraud, for the more he is
really afraid inwardly the more courageously will he act just to hide
his fear.
Since, however, the bullet-proof helmet is worn officially nowadays
there seems no reason whatever why the bullet-proof waistcoat should
not be adopted officially too. It is very light and very flexible and it
is claimed that it is quite effectual in stopping rifle and machine-gun
bullets.
Thus we see in what different ways inventions grow. Some are warlike
from first to last, like the gun and the torpedo, but we find a vast
range of peaceful things growing into implements of warfare, as the
farmer's tractor has been developed into the tank, while not less
interesting are the old ideas revived and adapted to modern needs,
exemplified by the hand-grenade and the chain armour.