CHAPTER XVI_Inventions of the Great War

RECLAIMING THE VICTIMS OF THE SUBMARINE

Nearly fifteen million tons of shipping lie at the bottom of the sea,

sunk by German U-boats, and the value of these ships with their cargo

is estimated at over seven billion dollars. In one year, 1917, the loss

was nearly a million dollars a day.

Of course these wrecks would not be worth anything like that now, if

they were raised and floated. Much of the cargo would be so damaged by

its long immersion in salt water that it would be absolutely valueless,

but there are many kinds of merchandise that are not injured in the

least by water. Every ship carries a certain amount of gold and silver;

and then the ship's hull itself is well worth salving, provided it was

not too badly damaged by the torpedo that sank it. Altogether, there

is plenty of rich treasure in the sea awaiting the salvor who is bold

enough to go after it.

To be sure, not all of the U-boat's victims were sunk in deep water.

Many torpedoed vessels were beached or succeeded in reaching shallow

water before they foundered. Some were sunk in harbors while they lay

at anchor, before the precaution was taken of protecting the harbors

with nets. The Allies did not wait for the war to end before trying to

refloat these vessels. In fact, during the war several hundred ships

were raised and put back into service. A special form of patch was

invented to close holes torn by torpedoes. Electric pumps were built

which would work under water and these were lowered into the holds

of ships to pump them out. The salvors were provided with special

gas-masks to protect them from poisonous fumes of decayed matter in the

wrecks.

Our own navy has played an important part in salvage. Shortly after

we entered the war, all the wrecking-equipment in this country was

commandeered by the government and we sent over to the other side

experienced American salvors, provided with complete equipment of

apparatus and machinery.

The majority of wrecks, however, are found in the open sea, where it

would have been foolish to attempt any salvage-operations because of

the menace of submarine attack. On at least one occasion a salvage

vessel, while attempting to raise the victims of a submarine, fell,

itself, a prey to a Hun torpedo. Now that this menace has been removed,

such vessels as lie in comparatively shallow water, and in positions

not subject to sudden tempests, can be raised by the ordinary methods;

or if it is impracticable to raise them, much of their cargo can be

reclaimed. However, most of the torpedoed ships lie at such depths that

their salvage would ordinarily be despaired of.

IN THE DEPTHS OF THE SEA

It will be interesting to look into conditions that exist in deep

water. Somehow the notion has gone forth that a ship will not surely

sink to the very bottom of the deep sea, but on reaching a certain

level will find the water so dense that even solid iron will float,

as if in a sea of mercury, and that here the ship will be maintained

in suspension, to be carried hither and yon by every chance current.

Indeed, it makes a rather fantastic picture to think of these lost

ships drifting in endless procession, far down beneath the cold green

waves, and destined to roam forever like doomed spirits in a circle of

Dante's Inferno.

But the laws of physics shatter any such illusion and bid us paint

a very different picture. Liquids are almost incompressible. The

difference in density between the water at the surface of the sea and

that at a depth of a mile is almost insignificant. As a matter of fact,

at that depth the water would support only about half a pound more

per cubic foot than at the surface. The pressure, however, would be

enormous. Take the _Titanic_, for instance, which lies on the bed of

the ocean in water two miles deep. It must endure a pressure of about

two long tons on every square inch of its surface. Long before the

vessel reached the bottom her hull must have been crushed in. Every

stick of wood, every compressible part of her structure and of her

cargo, must have been staved in or flattened. As a ship sinks it is not

the water but the ship that grows progressively denser. The _Titanic_

must have actually gained in weight as she went down, and so she must

have gathered speed as she sank.

We may be certain, therefore, that every victim of Germany's ruthless

U-boats that sank in deep water lies prone upon the floor of the sea.

It matters not how or where it was sunk, whether it was staggered by

the unexpected blow of the torpedo and then plunged headlong into

the depths of the sea, or whether it lingered, mortally wounded, on

the surface, quietly settling down until the waves closed over it.

Theoretically, of course, a perfect balance might be reached which

would keep a submerged vessel in suspension, but practically such a

condition is next to impossible. Once a ship has started down, she will

keep on until she reaches the very bottom, whether it be ten fathoms or

ten hundred.

A SUBMARINE GRAVEYARD

Instead of the line of wandering specters, then, we must conjure up a

different picture, equally weird--an under-world shrouded in darkness;

for little light penetrates the deep sea. Here in the cold blackness,

on the bed of the ocean, the wrecks of vessels that once sailed proudly

overhead lie still and deathly silent--some keeled over on their sides,

some turned turtle, and most of them probably on even keel. Here and

there may be one with its nose buried deep in the mud; and in the

shallower waters we may come across one pinned down by the stern, but

with its head buoyed by a pocket of air, straining upward and swaying

slightly with every gentle movement of the sea, as if still alive.

This submarine graveyard offers wonderful opportunities for the

engineer, because the raising of wrecked vessels is really a branch

of engineering. It is a very special branch, to be sure, and one that

has not begun to receive the highly concentrated study that have such

other branches as tunneling, bridge-construction, etc. Nevertheless it

is engineering, and it has been said of the engineer that his abilities

are limited only by the funds at his disposal. Now he has a chance to

show what he can do, for there are hundreds of vessels to be salved

where before there was but one. The vast number of wrecks in deep water

will make it pay to do the work on a larger and grander scale than has

been possible heretofore. Special apparatus that could not be built

economically for a single wreck may be constructed with profit if a

number of vessels demanding similar treatment are to be salved.

The principal fields of German activities were the Mediterranean Sea

and the waters surrounding the British Isles. Although the submarine

zone covered some very deep water, where the sounding-lead runs down

two miles without touching bottom, obviously more havoc could be

wrought near ports where vessels were obliged to follow a prescribed

course, and so most of the U-boat victims were stricken when almost in

sight of land. In fact, as was pointed out in a previous chapter, it

was not until efficient patrol measures made it uncomfortable for the

submarines that they pushed out into the open ocean to pursue their

nefarious work. The _Lusitania_ went down only eight miles from Old

Head of Kinsale, in fifty fathoms of water.

If we draw a line from Fastnet Rock to the Scilly Islands and from

there to the westernmost extremity of France, we enclose an area in

which the German submarines were particularly active. The soundings

here run up to about sixty fathoms in some places, but the prevailing

depth is less than fifty fathoms. In the North Sea, too, except for a

comparatively narrow lane along the Norwegian coast--which, by the way,

marked the safety lane of the German blockade zone--the chart shows

fifty fathoms or under. If our salvors could reach down as far as that,

most of the submarine victims could be reclaimed. But fifty fathoms

means 300 feet, which is a formidable depth for salvage work. Only one

vessel has ever been brought up from such a depth and that was a small

craft, one of our submarines, the _F-4_, which sank off the coast of

Hawaii four years ago.

DIFFERENT WAYS OF SALVING A WRECK

There are four well-known methods of raising a vessel that is

completely submerged. Of course, if the ship is not completely

submerged, the holes in her hull may be patched up, and then when her

hull is pumped out, the sea itself will raise the ship, unless it be

deeply embedded in sand or mud. If the vessel is completely submerged,

the same process may be resorted to, but first the sides of the hull

must be extended to the surface to keep the water from flowing in as

fast as it is pumped out. It is not usual to build up the entire

length of the ship. If the deck is in good condition, it may suffice

to construct coffer-dams or walls around several of the hatches. But

building up the sides of a ship, or constructing coffer-dams on the

ship's deck is a difficult task, at best, because it must be done under

water by divers.

A record for this type of salvage work was established by the Japanese

when they raised the battle-ship _Mikasa_ that lay in some eighty feet

of water. Her decks were submerged to a depth of forty feet. It is

doubtful that this salvage work could be duplicated by any other people

of the world. The wonderful patriotism and loyalty of the Japanese race

were called forth. It is no small task to build a large coffer-dam

strong enough to withstand the weight of forty feet of water, or a

pressure of a ton and a quarter per square foot, even when the work is

done on the surface. Perfect discipline and organized effort of the

highest sort were required. Labor is cheap in Japan and there was no

dearth of men for the work. Over one hundred divers were employed. In

addition to the coffer-dam construction much repair work was necessary.

Marvelous acts of devotion and heroism were performed. It is rumored

that in some places it was necessary for divers to close themselves in,

cut their air supply-pipes and seal themselves off from the slightest

chance of escape; and that there were men who actually volunteered to

sacrifice their lives in this way for their beloved country and its

young navy. Where, indeed, outside of the Land of the Rising Sun could

we find such patriotic devotion!

A second salvage method consists in building a coffer-dam not on the

ship but around it, and then pumping this out so as to expose the ship

as in a dry-dock. Such was the plan followed out in recovering the

_Maine_. Obviously, it is a very expensive method and is used only in

exceptional cases, such as this, in which it was necessary to make a

post-mortem examination to determine what caused the destruction of the

vessel. Neither of these methods of salvage will serve for raising a

ship sunk in deep water.

RAISING A SHIP ON AIR

A salvage system that has come into prominence within recent years

consists in pumping air into the vessel to drive the water out, thus

making the boat light enough to float. This scheme can be used only

when the deck and bulkheads of the boat are strongly built and able

to stand the strain of lifting the wreck, and when the hole that sank

the vessel is in or near the bottom, so as to allow enough airspace

above it to lift the boat. The work of the diver in this case consists

of closing hatches and bulkhead doors, repairing holes in the upper

part of the hull, and generally strengthening the deck. It must be

remembered that a deck is built to take the strain of heavy weights

bearing down upon it. It is not built to be pushed up from beneath,

so that frequently this method of salving is rendered impracticable

because the deck itself cannot stand the strain.

[Illustration: Climbing into an Armored Diving Suit]

[Illustration: Lowering an Armored Diver into the Water]

A more common salvage method consists in passing cables or chains under

the wreck and attaching them to large floats or pontoons. The slack in

the chains is taken up when the tide is low, so that on the turn of

the tide the wreck will be lifted off the bottom. The partially raised

wreck is then towed into shallower water, until it grounds. At the

next low tide, the slack of the chains is again taken in, and at

flood-tide the wreck is towed nearer land. The work proceeds step by

step, until the vessel is moved inshore far enough to bring its decks

awash; when it may be patched up and pumped out. Where the rise of the

tide is not sufficient to be of much assistance, hydraulic jacks or

other lifting-apparatus are used.

[Illustration: A Diver's Sea Sled ready to be towed along the bed of

the sea]

[Illustration: The Sea Sled on Land showing the forward horizontal and

after vertical rudders]

SALVING THE U. S. SUBMARINE F-4

If the salvor could always be assured of clear weather, his troubles

would be reduced a hundredfold, but at best it takes a long time to

perform any work dependent upon divers, and the chances are very good

when they are operating in an unsheltered spot, that a storm may come

up at any time and undo the result of weeks and months of labor. This

is what happened when the submarine _F-4_ was salved. After a month

of trying effort the submarine was caught in slings hung from barges,

lifted two hundred and twenty-five feet, and dragged within a short

distance of the channel entrance of the harbor, where the water was

but fifty feet deep. But just then a violent storm arose, which made

the barges surge back and forth and plunge so violently that the

forward sling cut into the plating of the submarine and crushed it.

The wreck had to be lowered to the bottom and the barges cut free to

save them from being smashed. At the next attempt to raise the _F-4_

pontoons were again used, but instead of being arranged to float on the

surface, they were hauled down to the wreck and made fast directly to

the hull of the submarine. Then when the water was forced out of the

pontoons with compressed air, they came up to the surface, bringing the

submarine with them. In this way all danger of damage due to sudden

storms was avoided because water under the surface is not disturbed

by storms overhead; and when the wreck was floated, the pontoons and

submarine formed a compact unit.

While this method of salvage seems like a very logical one for work

in the open sea, one is apt to forget how large the pontoons must be

to lift a vessel of any appreciable size. Not only must they support

their own dead weight, together with that of the sunken vessel, but

some allowance must usually be made for dragging the wreck out of the

clutches of a sandy or muddy bottom. Imagine the work of building

pontoons large enough to raise the _Lusitania_. They would have to have

a combined displacement greater than that of the vessel itself, and

they would have to be so large that they would be very unwieldy things

to handle in a seaway. It is for this reason that submarine pontoons

are not often used to take the entire weight of the vessel. So far

they have been employed mainly to salve small ships and then only to

take a portion of the weight, the principal work being done by large

wrecking-cranes. Instead of horizontal pontoons it has been suggested

that vertical pontoons be employed, so as to provide a greater

lifting-power without involving the use of enormous unwieldy units.

Ships are not built so that they can be picked up by the ends. Such

treatment would be liable to break their backs in the middle. Were

they built more like a bridge truss, the salvor's difficulties would

be materially lessened. It would be a much simpler matter to raise a

vessel with pontoons were it so constructed that the chains of the

pontoon could be attached to each end of the hull. But because a ship

is built to be supported by the water uniformly throughout its length,

the salvor must use a large number of chains, properly spaced along

the hull, so as to distribute the load uniformly and see that too much

weight does not fall on this or that pontoon.

The main problem, however, is to get hold of the wreck and this

requires the services of divers, so that if there were no other

limiting factor, the depth to which a diver may penetrate and perform

his duties sets the mark beyond which salvage as now conducted is

impossible.

[Illustration: (C) International Film Service

The Diving Sphere built for Deep Sea Salvage Operations]

A common diver's suit does not protect the diver from hydraulic

pressure. Only a flexible suit and a thin layer of air separates him

from the surrounding water. This air must necessarily be of the same

pressure as the surrounding water. The air that is pumped down to the

diver not only serves to supply his lungs, but by entering his blood

transmits its pressure to every part of his anatomy. As long as the

external pressure is equalized by a corresponding pressure within him,

the diver experiences no serious discomfort. In fact, when the pressure

is not excessively high he finds it rather exhilarating to work under

such conditions; for, with every breath, he takes in an abnormal amount

of oxygen. When he returns to the surface he realizes that he has

been working under forced draft. He is very much exhausted and he is

very hungry. It takes a comparatively short time to build up the high

internal pressure, which the diver must have in order to withstand

the pressure of the water outside, but it is the decompression when

he returns to the surface that is attended with great discomfort and

positive danger. If the decompression is not properly effected, the

diver will suffer agonies and even death from the so-called "Caisson

Disease."

[Illustration: The Pneumatic Breakwater--Submerged Air Tubes protecting

a California Pier from Ocean Storms]

A HUMAN SODA-WATER BOTTLE

We know now a great deal more than we used to know about the effect

of compressed air on the human system, and because of this knowledge

divers have recently descended to depths undreamed of a few years ago.

When a diver breathes compressed air, the oxygen is largely consumed

and exhaled from the lungs in the form of carbon-dioxide, but much of

the nitrogen is dissolved in the blood and does not escape. However,

like a bottle of soda-water, the blood shows no sign of the presence of

the gas as long as the pressure is maintained. But on a sudden removal

of the pressure, the blood turns into a froth of nitrogen bubbles, just

as the soda-water froths when the stopper of the bottle is removed.

This froth interrupts the circulation. The release of pressure is felt

first in the arteries and large veins. It takes some time to reach all

the tiny veins, and serious differences of pressure are apt to occur

that often result in the rupture of blood-vessels. The griping pains

that accompany the "Caisson Disease" are excruciating. The only cure is

to restore the blood to its original pressure by placing the patient

in a hospital lock, or boiler-like affair, where compressed air may be

admitted; and then to decompress the air very slowly.

It is possible to relieve the pressure in a bottle of soda-water so

gradually that the gas will pass off without the formation of visible

bubbles, and that is what is sought in decompressing a diver. After

careful research it has been found that the pressure may be cut down

very quickly to half or even less of the original amount, but then

the diver must wait for the decompression to extend to the innermost

recesses of his being and to all the tiny capillaries of his venous

system.

In the salvage of the _F-4_ a diver went down 306 feet, and remained

on the bottom half an hour. The pressure upon him was 135 pounds per

square inch, or about 145 tons on the surface of his entire body. Some

idea of what this means may be gained if we consider that the tallest

office building in the world does not bear on its foundations with a

greater weight than 215 pounds to the square inch or only about 50 per

cent more than the crushing pressure this diver had to endure.

It took the diver a very short time to go down. On coming up he

proceeded comparatively rapidly until he reached a depth of 100 feet.

There he found the bottom rung of a rope ladder. On it he was obliged

to rest for several minutes before proceeding to the next rung. The

rungs of this ladder were 10 feet apart, and on each rung the diver

had to rest a certain length of time, according to a schedule that had

been carefully worked out. At the top rung, for instance, only 10 feet

from the surface, he was obliged to wait forty minutes. In all, it

took him an hour and forty-five minutes to come up to the surface. The

decompression was complete and he suffered no symptoms of the "Caisson

Disease." But he was so exhausted from his efforts that he was unfit

for work for several days. Yet the operations that he performed at the

depth of 300 feet would not have taken more than a few minutes on the

surface.

A SUBMARINE REST-CHAMBER

The Germans have paid a great deal of attention to deep-diving

operations, and no doubt while their U-boats were sinking merchant

ships German salvors were anticipating rich harvests after hostilities

ended. One scheme they developed was a submarine rest-chamber which

could be permanently located on the bottom of the sea close to the

point where the salvage operations were to take place. This chamber

consists of a large steel box which is supplied with air from the

surface and in which divers may make themselves comfortable when they

need a rest after arduous work. Entrance to the chamber is effected

through a door in the floor. The pressure of the air inside prevents

the water from rising into the chamber and flooding it. From this

submarine base the divers may go out to the wreck, either equipped

with the ordinary air-tube helmets or with self-regenerating apparatus

which makes them independent of an air-supply for a considerable period

of time. When the diver has worked for an hour or two, or when he is

tired, he may return to this chamber, remove his helmet, eat a hearty

meal, take a nap if he needs it, and then return to the salvage work

without going through the exhausting operation of decompressing.

CUTTING METAL UNDER WATER WITH A TORCH

The work of the diver usually consists of far more than merely passing

lines under a sunken hull. It is constantly necessary for him to cut

away obstructing parts. He must sometimes use blasting-power. Pneumatic

cutting-tools frequently come into play, but the Germans have lately

devised an oxy-hydrogen torch for underwater use, with which the diver

can cut metal by burning through it. This is accomplished by using a

cup-shaped nozzle through which a blast of air is projected under such

pressure that it blows away the water over the part to be cut. The

oxygen and hydrogen jets are then ignited electrically, and the work

of cutting the metal proceeds in the hole in the water made by the

air-blast. A similar submarine torch has recently been developed by

an American salvage company. It was employed successfully in cutting

drainage-holes in the bulkheads of the _St. Paul_, which was raised in

New York Harbor in the summer of 1918.

EXPLORING THE SEA BOTTOM IN A DIVER'S SLED

The diver's sled is still another interesting German invention. It is

a sled provided with vertical and horizontal rudders, which is towed

by means of a motor-boat at the surface. The diver, seated on the

sled, and provided with a self-contained diving-suit, can direct the

motor-boat by telephone and steer his sled up and down and wherever

he chooses. And so without any physical exertion, he can explore the

bottom of the sea and hunt for wrecks.

ARMORED DIVING-SUITS

From time to time attempts have been made to construct a diver's suit

that will not yield to the pressure of the sea, so that the diver

will not be subjected to the weight of the water about him, but can

breathe air at ordinary atmospheric pressure. Curious armor of steel

has been devised, with articulated arms and legs, in which the diver is

completely encased. With the ordinary rubber suit, the diver usually

has his hands bare, because he is almost as dependent upon the sense

of touch as a blind man. But where the pressure mounts up to such a

high degree that a metal suit must be used, no part of the body may be

exposed. If a bare hand were extended out of the protecting armor it

would immediately be mashed into a pulp and forced back through the

opening in the arms of the suit. The best that can be done, then, is to

furnish the arms of the suit with hooks or tongs or other mechanical

substitutes for hands which will enable the diver to make fast to the

wreck or various parts of it.

But if a diver feels helpless in the bag of a suit now commonly worn,

what would he do when encased in a steel boiler; for that is virtually

what the armored suit is! A common mistake that inventors of armor

units have made is to fail to consider the effects of the enormous

hydraulic pressure on the joints of the suit. In order to make them

perfectly tight, packings must be employed, and these are liable to be

so jammed by the hydraulic pressure that it is well nigh impossible to

articulate the limbs. Again, the construction of the suit should be

such that when a limb is flexed it would not displace any more water

than when in an extended position, and vice versa. A diver may find

that he cannot bend his arm, because in doing so he would expand the

cubical content of his armor by a few cubic inches, and to make room

for this increment of volume it would be necessary for him to lift

several hundred pounds of water. The hydraulic pressure will reduce the

steel suit to its smallest possible dimensions, which may result either

in doubling up the members or extending them rigidly.

But these difficulties are not insuperable. There is no reason why a

steel manikin cannot be constructed with a man inside to direct its

movements.

THE SALVOR'S SUBMARINE

Other schemes have been devised to relieve the diver of abnormally

high air-pressure. One plan is to construct a large spherical

working-chamber strong enough to withstand any hydraulic pressure that

might be encountered. This working-chamber is equipped with heavy

glass ports through which the workers can observe their surroundings

in the light of an electric search-light controlled from within the

chamber. The sphere is to be lowered to the wreck from a barge, with

which it will be in telephonic communication and from which it will

be supplied with electric current to operate various electrically

driven mechanisms. By means of electromagnets this sphere may be

made fast to the steel hull of the vessel and thereupon an electric

drill is operated to bore a hole in the ship and insert the hook of

a hoisting-chain. This done, the sphere would be moved to another

position, as directed by telephone and another chain made fast. The

hoisting-chains are secured to sunken pontoons and after enough of the

chains have been attached to the wreck the pontoons are pumped out and

the wreck is raised.

It is a pity that ship-builders have not had the forethought to provide

substantial shackles at frequent intervals firmly secured to the

framing. A sunken vessel is really a very difficult object to make

fast to and the Patent Office has recorded many very fantastic schemes

for getting hold of a ship's hull without the use of divers. One man

proposes the use of a gigantic pair of ice-tongs; and there have been

no end of suggestions that lifting-magnets be employed, but no one who

has any idea of how large and how heavy such magnets must be would give

these suggestions any serious consideration.

But, after all, the chief obstacle to salvage in the open sea is the

danger of storms; months of preparation and thousands of dollars' worth

of equipment may be wiped out in a moment.

FIGHTING THE WAVES WITH AIR

However, there has been another recent development which may have a

very important bearing on this problem of deep-sea salvage work. It

has often been observed that a submerged reef, twenty or thirty feet

below the surface, may act as a breakwater to stop the storming waves.

An inventor who studied this phenomenon arrived at the theory that the

reefs set up eddies in the water which break up the rhythm of the

waves and convert them into a smother of foam just above the reef.

Thereupon he conceived the idea of performing the same work by means of

compressed air. He laid a pipe on the sea bottom, forty or fifty feet

below the surface, and pumped air through it. Just as he had expected,

the line of air bubbles produced exactly the same effect as the

submerged reef. They set up a vertical current of water which broke up

the waves as soon as they struck this barrier of air.

The "pneumatic breakwater," as it is called, has been tried out on an

exposed part of the California coast, to protect a long pier used by an

oil company. It has proved so satisfactory that the same company has

now constructed a second breakwater about another pier near by. There

is no reason why a breakwater of this sort should not be made about a

wreck to protect the workers from storms. Where the water is very deep,

it would not be necessary to lay the compressed-air pipe on the bottom,

but it could be carried by buoys at a convenient depth.

Summing up the situation, then, there are two serious bars to the

successful salvage of ships sunk in the open sea--the wild fury of the

waves on the surface; and the silent, remorseless pressure of the deep.

The former is the more to be feared; and if the waves really can be

calmed, considerably more than half the problem is solved. As for the

pressure of the sea, it can be overcome, as we have seen, either by

the use of special submarine mechanisms, or of man-operated manikins

or even of unarmored divers. We have reached a very interesting stage

in the science of salvage, with the promise of important developments.

Fifty fathoms no longer seems a hopeless depth.

Even in times of peace the sea exacts a dreadful toll of lives and

property. Before the war the annual loss by shipwreck around the

British Isles alone was estimated at forty-five million dollars. But

the war, although it was frightfully destructive to shipping, may

in the long run save more vessels than it sank; for it has given us

sound-detectors which should remove the danger of collisions in foggy

weather, and the wireless compass, which should keep ships from running

off the course and on the rocks. And now, if salvage engineering

develops as it should, the sea will be made to give up not only much

of the wealth it swallowed during the war, but also many of the rich

cargoes of gold and silver it has been hoarding since the days of the

Spanish galleon.

INDEX

Air, fighting waves, 334

raising ship, on, 319

war in, 123

Airplane, ambulance, 146

armored, 139

artillery-spotting, 131

camera, 173

cartridges, 131

classes of work, 127

fighting among clouds, 137

flying boats, 144

gasolene tank, 130

giant, 132

hospital, 146

launching from ship, 303

Liberty motor, 142

scouting, 125

scouts, 128

speed of, 134

spotting, 177

training spotters, 180

wireless telephone, 194