THE MODERN SUBMARINE

Holland and Lake must be considered the fathers of the modern submarine. This claim is not made in a spirit of patriotic boastfulness, though, of course it is true that the latter was an American by birth, and the former by choice, and that, therefore, we, as a nation, have a right to be proud of the accomplishments of these two fellow-citizens of ours. Without wishing to detract anything from the value of the work done by many men in many countries towards the development of the submarine after and contemporaneously with Holland and Lake, it still remains true that the work which these two did formed the foundation on which all others built. To-day, no submarine worthy of the name, no matter where it has been built and no matter where and how it is used, is without some features which are typical of either the Holland or Lake type. In many instances, and this is true especially of submarines of the highest type and the greatest development, the most significant characteristics of the Holland and Lake boats have been combined.

During the years that followed the small beginnings of Holland and Lake, vast and highly efficient organizations have been built up to continue and elaborate their work. Death claimed Mr. Holland shortly after the outbreak of the great war, on August 12, 1914. Mr. Lake in 1917 was still personally connected with and the guiding spirit of the extensive industrial establishments which have been created at Bridgeport, Conn., as a result of his inventions. He, too, surrounded himself with a corps of experts who in co-operation with him have brought the Lake submarines to a point of perfection which at the time of the Argonaut's first trip would have appeared all but impossible.

Roughly speaking, the beginning of the twentieth century may be called the turning point in the history of submarine invention and the beginning of the modern submarine. Although, as we have heard, various governments, especially those of France and the United States, interested themselves in the submarine question and appropriated small sums of money towards its solution previous to 1900, it was only after that year that governmental interest and influence were set to work with determination and purpose on behalf of submarine inventors. Quite naturally this resulted in increased popular interest. Experimental work on and with submarines no longer had to rely exclusively on private capital, frequently inconveniently timid and limited, but could count now on the vast financial resources of all the great nations of the world. This also made available the unlimited intellectual resources of serious scientists in every part of the universe. Mechanical and electrical engineers, naval designers and constructors, active men of finance and business, and quiet thinkers and investigators in laboratories began to interest themselves in the further development of the submarine.

The United States for a number of years after its adoption of the Holland type remained true to its first choice. Between 1900, when the first Holland boat was bought by the United States Government, and 1911 all the United States submarine, boats were of the Holland type. In the latter year, however, it was decided to give the Lake boat a trial and since that time a number of boats of this type have been built. In all essential features both the Holland and Lake boats of later days were very similar to the original boats of these two types. In all the details, however, immense progress was made. Each new boat thus became greatly superior to its predecessors. This was especially true in regard to size and speed and the improvements made in these two respects naturally resulted in a corresponding increase in radius of activity. The passing years also brought a wonderful refinement of all the technical details of the submarine boats. Practically every feature was developed to a remarkable degree. There is, indeed, a great difference between the submarine boats of the early twentieth century which had to rely on their conning-tower for steering, and more recent boats with their wonderful periscopes and gyro compasses. Similar progress was made in the development of the means of propulsion. The engines used for surface travelling became more powerful and efficient. This was also true of the electric motors, batteries, and accumulators employed in the submerged state. The problem of ventilation likewise has been worked out to such an extent that in the most modern submarines most of the inconveniences experienced by the crews of earlier boats have been removed. This perfection of technical details which was thus gradually approached also permitted a very considerable increase in the fighting power of submarine boats. The number of torpedo tubes was increased and it became possible to carry a larger reserve stock of torpedoes. Submarines of to-day furthermore carry guns varying in calibre, attaining in some instances four inches, and when in later years it became evident that one of the most dangerous enemies of the submarine was the airplane, some of the boats were equipped even with anti-aircraft guns.

In the United States Navy the submarine has never been popular. Indeed it is by no means certain that in comparison with other navies of the world the United States was not better off in underwater boats in 1911 than she was three years later when the warcloud broke. The bulk of our naval opinion has always been for the dreadnoughts. A change of political administration at Washington in 1912 gave a temporary setback to naval development, and the submarines, being still a matter of controversy, languished. Few were built and of those few many showed such structural weakness that the reports of their manœuvres were either suppressed, or issued in terms of such broad generality that the public could by no possibility suspect, what all the Navy knew to be the fact, that the submarine flotilla of the United States was weak to the point of impotence.

Happily we had nearly three years in which to observe the progress of the war before becoming ourselves embroiled in it. During this period our submarine fleet was somewhat increased, and upon our actual entrance upon the struggle a feverish race was begun to put us on an equality with other nations in underwater boats. It would have been too late had any emergency arisen. But Germany had no ships afloat to be attacked by our submarines had we possessed them. Her own warfare upon our merchant shipping could not be met in kind, for submarines cannot fight submarines. We have, therefore, up to the present time, not suffered from the perilous neglect with which we long treated this form of naval weapon.

Indeed the submarine fleet of the United States Navy at the beginning of the war was so inconsiderable that foreign writers on the subject ignored it. In 1900 we had purchased nine of the type of submarines then put out by the Holland Company. One of these, the first in actual service, known as the "Baby" Holland was kept in commission ten years and upon becoming obsolete was honoured by being taken in state to the Naval Academy at Annapolis and there mounted on a pedestal for the admiration of all comers. She was 59 feet long and would make a striking exhibit placed next to one of the new German submersible cruisers which exceed 300 feet and have a displacement of 5000 tons. These first Holland ships which long constituted the entire underwater force of the United States were but trivial affairs compared with the modern vessel. Their displacement was but 122 tons, their engines for surface navigation were of 160 horse-power, gasoline, and for underwater navigation 70 horse-power, electric. They carried but one torpedo tube and two extra torpedoes and had a radius of action of but 300 miles. At that time in fact the naval theory was that submarines were coast defence vessels altogether. After this war they are likely to form part of the first battle line of every navy. Yet these pioneer vessels established their seaworthiness well in 1911, when four of them accompanied by a parent ship to supply them with fresh stocks of fuel and to render assistance in case of need, crossed the Pacific Ocean under their own power to the Philippines. This exploit tended to popularize these craft in the Navy Department, and soon after larger vessels known as the "Viper" class were ordered. One of these was called the Octopus, the first submarine to be fitted with twin screws. In many ways she represented a distinct advance in the art of submarine construction. She was in fact the first vessel built with the distinct idea of being a cruising, as well as a harbour defence ship. Her type proved successful in this respect. The Octopus further established a record for deep sea submergence in 1907 when she descended to a depth of 205 feet off Boston, returning to the surface in entire safety.

The ability to withstand the pressure of the water at great depths is a vital quality of a successful submarine. One American submarine narrowly escaped destruction because of structural weakness in this respect. She had by accident descended a few feet below the normal depth at which such boats navigate. The water pressure affected the valves which refused to work and the vessel slowly sank deeper and deeper. At a recorded depth of 123 feet the sinking of the vessel became so much more rapid that the crew with frantic endeavours sought at once to stop the leaks and pump out the water which had entered. At that depth there was a pressure of 153-½ pounds upon every square inch of the surface of the submarine. This the workers at the one hand pump had to overcome. It was a savage and a desperate struggle but the men finally won and the vessel regained the surface. As a result of this experience every navy prescribed submergence tests for its submarines before putting them into commission. How to make these tests was perplexing at first. A government did not want to send men down in a steel casket to see just how far they could go before it collapsed. But if no observer accompanied the ship it would be impossible to tell at what depth leakage and other signs of weakness became apparent. An Italian naval architect, Major Laurenti, whose submarines are now found in every navy of the world, invented a dock in which these tests can be made up to any desired pressure while the observers inside the submarine are in communication with those without and the pressure can be instantly removed if signs of danger appear. In the United States Navy boats to be accepted must stand a pressure equivalent to that encountered at 200 feet. In the German navy the depth prescribed is 170 feet. Under normal conditions submarines seldom travel at a depth of more than 100 feet although the "F-1" of the United States Navy accomplished the remarkable feat of making a six-hour cruise in San Francisco Bay at a depth of 283 feet. At this depth the skin of the ship has to withstand a pressure of no less than 123 pounds per square inch.

Specific information as to the nature of submarine construction in the United States since the beginning of the war in 1914 is jealously guarded by the Navy Department. In broad general terms the number of ships under construction is revealed to the public, but all information as to the size of individual vessels, their armour or the qualities of novelty with which every one hopes and believes American inventive genius has invested them, are kept secret. The Navy Year Book of 1916 summarized our submarine strength at that time as follows:

Great Britain like the United States continued for many years to build submarines of the Holland type. Naturally all the recent improvements were incorporated in the British boats. Very little, however, is known concerning the details of the more recent additions to the British submarine flotilla because of the secrecy maintained by the British authorities in war time.

At the beginning of the present war, the British navy possessed 82 active submarines of 5 different classes. They were all of the Holland type, but in each class there were incorporated vast improvements over the preceding class. Displacement, size, motive power, speed, radius of action, and armament were gradually increased until the "E" class contained boats possessing the following features: Submerged displacement, 800 tons; length 176 feet; beam 22-½ feet; heavy oil engines of 2000 H.-P.; electric engines of 800 H.-P.; surface speed 16 knots; submerged speed 10 knots; cruising range 5000 miles; armament: 4 torpedo tubes, space for 6 torpedoes, and two 3-inch quick-firing, high-angle, disappearing guns; armoured conning-towers and decks; wireless equipment; 3 panoramic periscopes.

At the same time 22 other submarines were said to be in course of construction. Some of these were of the "F" class (Holland type), similar to the "E" class except that every single characteristic had been greatly increased, in many instances even doubled. In addition to the "F" class Holland-type boats, there were also under construction a number of boats of different types designated respectively as "V," "W," and "S" class. The "V" class were of the Lake type, the "W" of the French "Laubeuf" type, and the "S" class of the Italian "F. I. A. T." or Laurenti type; both of the last named were adaptations of the Lake type.

France, which was for many years the prodigal of the nations when it came to submarine building has continued this tendency. In a way this liberal expenditure of money did not pay particularly well. For, although it resulted in the creation of a comparatively large submarine fleet, this fleet contained boats of every kind and description. Quite a number of the boats were little more than experiments and possessed not a great deal of practical value. The manning and efficient handling of a fleet having so little homogeneity naturally was a difficult matter and seriously restricted its fighting efficiency.

At the outbreak of the war France had 92 submarines in active service, belonging to 12 different classes. In addition there had also been built at various times 5 experimental boats which had been named: Argonaute, Amiral Bourgeoise, Archimède, Mariotte, and Charles Brun. The majority of the boats belonging to the various classes were of the Laubeuf type, an adaptation of the Lake type made for the French navy by M. Laubeuf, a marine engineer. In their various details these boats vary considerably. Their displacement ranges from 67 tons to 1000 tons, their length from 100 feet to 240 feet, their beam from 12 feet to 20 feet, their surface speed from 8-½ knots to 17 ½ knots, their submerged speed from 5 knots to 12 knots, the horse-power of their heavy oil engines from 1300 to 2000 and that of their electric motors from 350 to 900. Some of the boats, however, have steam engines, others gasoline motors, and still others steam turbines. The cruising range of the biggest and newest boats is 4000 miles. Armament varies with size, of course, the latest boats carrying 4 torpedo tubes for eight 18-inch torpedoes and two 14-pdr. quick-firing, high angle, disappearing guns.

Nine more submarines were in course of construction at the outbreak of war, most of which were of the improved "Gustave Zédé" class. During the war French shipyards were chiefly occupied with capital navy ships and it is not thought the submarine strength has been much increased.

Of the great naval powers, Germany was, strangely enough, the last to become interested in the building of a submarine fleet. This, however, was not due to any neglect on the part of the German naval authorities. It is quite evident from the few official records which are available that they watched and studied very carefully the development of the submarine and growth of the various submarine fleets. During the early years of the twentieth century, however, the Germans seemed to think that most of the boats that were being built then had not yet passed through the experimental stage and they also apparently decided that it would be just as well to wait until other nations had spent their money and efforts on these quasi experimental boats. Not until submarines had been built in the United States, England, and France which had proved beyond all doubt that they were practicable vessels of definite accomplishments, did the Germans seriously concern themselves with the creation of a German submarine fleet. When this period had been reached they went ahead with full power, and with the usual German thoroughness they adopted the best points from each of the various types developed by that time. The result of this attitude was a submarine boat built at first exclusively by Krupp and known as the "Germania" type. It was this type which formed the basis of the German submarine which has become known so extensively and disastrously during recent years. In most respects this type is perhaps more similar to the Lake type than to any other, although some features of the Holland type have been incorporated as well.

At the beginning of the war Germany was credited with only thirty submarines. Six more were then rapidly approaching completion and the German naval law passed some time before provided for the building of seventy-two submarines by the end of 1917. It is believed in fact that by that time the Germans had not less than two hundred Unterseeboots.

From the very beginning the Germans have designated their submarines by the letter "U" (standing for Unterseeboot) followed by numbers. The first boat was built in 1905 and was named "U-1." It was a comparatively small boat of 236 tons displacement. The motive power on the surface was a heavy-oil engine of 250 H.-P. Under water the boat was driven by electric motors of a little more than 100 H.-P. Submerged the "U-1" was capable of a speed of 7 knots only, which on the surface of the water could be increased to 10. Her radius of action was about 750 miles. Only one torpedo tube had been provided.

From this boat to the modern German submarine was indeed a long step taken in a comparatively short time. Not very much is known regarding modern German submarines, but the latest boats completed before the war were vessels of 900 tons displacement with heavy-oil engines of 2000 H.-P. and electric motors of 900 H.-P., possessing a surface and submerged speed of 18 and 10 knots respectively and a cruising radius of 4000 miles. They had four torpedo tubes for eight torpedoes, two 14-pdr. quick-firing guns, and two 1-pdr. high-angle anti-aircraft guns. Naturally they were also equipped with all the latest improvements, such as wireless apparatus, panoramic periscopes, armoured conning-towers, and decks. Since the outbreak of the war the Germans have built even more powerful submarine boats whose perfections in regard to speed, radius of action and armament became known through their accomplishments. Of these we will hear more in a later chapter.

At just what period of the war the Germans woke up to the vital importance to them of an enormous submarine fleet is not known. It may have been immediately upon the amazing exploit of Captain Weddigen in the North Sea. At any rate the war had not long progressed before the destruction caused by German submarine attacks began to awaken the apprehension of the Allies and neutral nations. Retaliation in kind was impossible. The Germans had neither merchant nor naval ships at sea to be sunk. The rapidity with which the volume of the loss inflicted upon merchant shipping grew indicated an equally rapid increase in the size of the German underwater fleet. Neutrals were enraged by the extension by the Germans of the areas of sea in which they claimed the right to sink neutral ships, and their growing disregard for the restraining principles of international law. How greatly they developed the submarine idea was shown by their construction in 1916 of vessels with a displacement of 2400 tons; a length of 279 feet, and a beam of 26 feet; a surface speed of 22 knots, cruising radius of 6500 miles, mounting 4 to 8 guns and carrying a crew of from 40 to 60. But it was reported that two vessels designed primarily for surface cruising, but nevertheless submersible at will, had been laid down of 5000 tons, a length of 414 feet, and a radius of 18,000 to 20,000 miles. These "submersible cruisers" as they were called, mounted 6 to 8 guns, 30 torpedo tubes, and carried 90 torpedoes. What part vessels of this type shall play in war is still to be determined.

Of the smaller naval powers, Italy comparatively early had become interested in the building of submarines. Most of her boats are of the Laurenti type—which is a very close adaptation of the Lake type. Russia and Japan, especially the latter, built up fairly efficient underwater fleets. The lesser countries, like Austria, Holland, Sweden, Denmark, Norway, and Spain have concerned themselves seriously with the creation of submarine fleets. The submarine boats of all of these countries in most instances were either of the Lake or Holland type though frequently they were built from plans of English, French or German adaptations rather than in accordance with the original American plans.

The exact number of submarines possessed now by the various navies of the world is a matter of rather indefinite knowledge. Great secrecy has been maintained by every country in this respect. From a variety of sources, however, it has been possible to compile the following list which at least gives an approximate idea of the respective strength of the various submarine fleets at the beginning of the war. The numbers assigned to each country are only approximate, however, and include both boats then in existence or ordered built: United States 57; Great Britain 104; France 92; Germany 36; Italy 28; Russia 40; Japan 15; Austria 12; Holland 13; Denmark 15; Sweden 13; Norway 4; Greece 2; Turkey 2; Brazil 3; Peru 2.

Having traced the development of the submarine from its earliest beginnings to recent times we are naturally now confronted with the question "What are the principal requirements and characteristics of the modern submarine?"

The submarine boat of to-day, in order to do its work promptly and efficiently, must first of all possess seaworthiness. This means that no matter whether the sea is quiet or rough the submarine must be able to execute its operations with a fair degree of accuracy and promptness and must also be capable of making continuous headway. Surface and underwater navigation must be possible with equal facility and it is necessary that a state of submergence can be reached without loss of time and without any degree of danger to the boat's safety. At all times, travelling above water or below, the submarine must possess mechanical means which will make it possible to control its evolutions under all conditions. Furthermore, the ability of the submarine to find and to observe objects in its vicinity must not be greatly reduced when it is in a submerged position. In the latter it also becomes of extreme importance that the provisions for ventilation are such that the crew of the submarine should lose as little as possible in its efficiency and comfort. A fair amount of speed both on and below the surface of the water is essential and the maintenance of the speed for a fairly long period of time must be assured.

In regard to their general outward appearance, submarines of various types to-day vary comparatively little. In many respects they resemble closely in shape, torpedo boats—the earlier submarines particularly. In size, of course, they differ in accordance with the purposes for which they have been designed. As compared with earlier submarines the most notable difference is that modern submarines possess more of a superstructure. Almost all of them are built now with double hulls. The space between the outer and the inner hull is utilized primarily for ballast tanks by means of which submergence is accomplished and stability maintained and regulated. Some of these tanks, however, are not used to carry water ballast, but serve as reservoirs for the fuel needed by the engines. The stability of the submarine and the facility with which it can submerge also depend greatly on the distribution of weight of its various parts. This problem has been worked out in such a way that to-day there is little room for improvement. Its details, however, are of too technical a nature to permit discussion in this place.

Hydroplanes both fore and aft are now generally used to assist in regulating and controlling stability in the submerged state. The motive power of the modern submarine is invariably of a two-fold type. For travelling on the surface internal combustion engines are used. The gasoline engine of former years has been displaced by Diesel motors or adaptations of them. Although these represent a wonderful advance over the engines used in the past there is still a great deal of room for improvement. The opinions of engineers in this respect vary greatly, American opinion being generally unfavourable to the Diesel type, and whether the final solution of this problem will lie in the direction of a more highly developed motor of Diesel type, of an improved gasoline engine, or of some other engine not yet developed, only the future can tell. Simplicity of construction and reliability of operation are the two essential features which must be possessed by every part of the power plant of a submarine. For underwater travel electric motors and storage batteries are employed exclusively. These vary, of course, in detail. In principle, however, they are very much alike. Although this combination of electric and oil power is largely responsible for having made the submarine what it is to-day, it is far from perfect. Mechanical complications of many kinds and difficulties of varying degrees result from it. Up to comparatively recently these were considered insurmountable obstacles. But engineers all over the world are giving their most serious attention to the problem of devising a way to remove these obstacles and continuous progress is made by them.

As an immediate result of the development of motive power in the submarine its speed both on and below the surface of the water as well as its radius of action has been materially increased. To-day submarines travel on the water with a speed which even a few years ago would have been thought quite respectable for the most powerful battleships or the swiftest passenger liners. And even under water, submarines attain a velocity which is far superior to that of which earlier submarines were capable on the surface of the water. How immensely extended the radius of action of the submarine has become in recent years, has impressed itself on the world especially in the last few years. Both English and French submarines have travelled without making any stops from their home ports to the Dardanelles and back again. And used to, and satiated as we are with mechanical wonders of all kinds the whole world was amazed when in 1916 German submarines made successful trips from their home ports to ports in the United States and returned with equal success. This meant a minimum radius of action of 3500 miles. In the case of the German U-boat which in 1916 appeared at Newport for a few hours, then attacked and sank some merchantmen off the United States coast and later was reported as having arrived safely in a German port, it has never been established whether the boat renewed its supplies of food and fuel on the way or carried enough to make the trip of some 7000 miles.

One other important feature without which submarines would have found it impossible to score such accomplishments is the periscope. In the beginning periscopes were rather crude appliances. They were very weak and sprung leaks frequently. Moisture, formed by condensation, made them practically useless. In certain positions the image of the object picked up by the periscope became inverted. Their radius of vision was limited, and in every way they proved unreliable and unsatisfactory. But, just as almost every feature of submarine construction was gradually developed and most every technical obstacle overcome, experts gradually concentrated their efforts on the improvement of periscopes. Modern periscopes are complicated optical instruments which have been developed to a very high point of efficiency. A combination of prisms and lenses makes it possible now to see true images clearly. Appliances have been developed to make the rotation of the periscope safe, prompt, and easy so that the horizon can be swept readily in every direction. Magnification can be established at will by special devices easily connected or disconnected with the regular instrument. The range of vision of the modern periscope is as remarkable as its other characteristics. It differs, of course, in proportion to the height to which the periscope is elevated above the surface of the water. In clear weather a submarine, having elevated its periscope to a height of 20 feet can pick up a large battleship at as great a distance as 6 miles, while observers on the latter, even if equipped with the most powerful optical instruments, are absolutely unable to detect the submarine. This great distance is reduced to about 4000 yards if the periscope is only 3 feet above the surface of the water and to about 2200 yards if the elevation of the periscope is 1 foot. But even the highly developed periscope of to-day, usually called "panoramic periscope," has its limitations. The strain on the observer's eyes is very severe and can be borne only for short periods. In dirty weather the objectives become cloudy and the images are rendered obscure and indefinite, although this trouble has been corrected, at least in part, by forcing a strong blast through the rim surrounding the observation glass. At night, of course, the periscope is practically useless. Formerly a shot which cut off the periscope near the water's edge might sink the boat. This has been guarded against by cutting off the tube with a heavy plate of transparent glass which does not obstruct vision but shuts off the entrance of water.

Important as the periscope is both as a means of observing the surroundings of the submarine and as a guide in steering it, it is not the only means of accomplishing the latter purpose. To-day every submarine possesses the most reliable type of compass available. At night when the periscope is practically useless or in very rough weather, or in case the periscope has been damaged or destroyed, steering is done exclusively by means of the compass. The latest type in use now on submarines is called the gyroscope compass which is a highly efficient and reliable instrument.

In the matter of ventilation the modern submarine also has reached a high state of perfection. The fresh air supply is provided and regulated in such a manner that most of the discomforts suffered by submarine crews in times past have been eliminated. The grave danger which formerly existed as a result of the poisonous fumes, emanating from the storage batteries and accumulators, has been reduced to a minimum. In every respect, except that of space, conditions of life in a submarine have been brought to a point where they can be favourably compared with those of boats navigated on the surface of the water. Of course, even at the best, living quarters in a submarine will always be cramped. However, it is so important that submarine crews should be continuously kept on a high plane of efficiency that they are supplied with every conceivable comfort permitted by the natural limitations of submarine construction.

Submarine boats so far have been used almost exclusively as instruments of warfare. One of their most important features, therefore, naturally is their armament. We have already heard something about the use of torpedoes by submarines. The early submarines had as a rule only one torpedo tube and were incapable of carrying more than two or three torpedoes. Gradually, however, both the number of torpedo tubes and of torpedoes was increased. The latest types have as many as eight or ten tubes and carry enough torpedoes to permit them to stay away from their base for several weeks. In recent years submarines have also been armed with guns. Naturally these have to be of light weight and small calibre. They are usually mounted so that they can be used at a high angle. This is done in order to make it possible for submarines to defend themselves against attacks from airships. The mountings of these guns are constructed in such a way that the guns themselves disappear immediately after discharge and are not visible while not in use. Though mounted on deck they are aimed and fired from below. As part of the armament of the submarine we must also consider the additional protection which they receive from having certain essential parts protected by armour plate.

All these features have increased the safety of submarine navigation to a great extent. In spite of the popular impression that submarine navigation entailed a greater number of danger factors than navigation on the surface of the water, this is not altogether so. If we stop to consider this subject we can readily see why rather the opposite should be true. Navigation under the surface of the water greatly reduces the possibility of collision and also the dangers arising from rough weather. For the results of the latter are felt to a much lesser degree below than on the surface of the water. Many other factors are responsible for the comparatively high degree of safety inherent in submarines. Up to the outbreak of the present war only about two hundred and fifty lives had been lost as a result to accidents to modern submarines. Considering that up to 1910 a great deal of submarine navigation was more or less experimental this is a record which can bear favourable comparison with similar records established by overwater navigation or by navigation in the air.

To the average man the thought of imprisonment in a steel tube beneath the surface of the sea, and being suddenly deprived of all means of bringing it up to air and light is a terrifying and nerve shattering thing. It is probably the first consideration which suggests itself to one asked to make a submarine trip. Always the newspaper headlines dealing with a submarine disaster speak of those lost as "drowned like rats in a trap." Men will admit that the progress of invention has greatly lessened the danger of accident to submarines, but nevertheless sturdily insist that when the accident does happen the men inside have no chance of escape.

As a matter of fact many devices have been applied to the modern submarine to meet exactly this contingency. Perhaps nothing is more effective than the so-called telephone buoy installed in our Navy and in some of those of Europe. This is a buoy lightly attached to the outer surface of the boat, containing a telephone transmitter and receiver connected by wire with a telephone within. In the event of an accident this buoy is released and rises at once to the surface. A flag attached attracts the attention of any craft that may be in the neighbourhood and makes immediate communication with those below possible. Arrangements can then be made for raising the boat or towing her to some point at which salvage is possible. An instance of the value of this device was given by the disaster to the German submarine "U-3" which was sunk at Kiel in 1910. Through the telephone the imprisoned crew notified those at the other end that they had oxygen enough for forty-eight hours but that the work of rescue must be completed in that time. A powerful floating derrick grappled the sunken submarine and lifted its bow above water. Twenty-seven of the imprisoned crew crept out through the torpedo tubes. The captain and two lieutenants conceived it their duty to stay with the ship until she was actually saved. In the course of the operations one of the ventilators was broken, the water rushed in and all three were drowned.

In some of the Holland ships of late construction there is an ingenious, indeed an almost incredible device by which the ship takes charge of herself if the operators or crew are incapacitated. It has happened that the shock of a collision has so stunned the men cooped up in the narrow quarters of a submarine that they are for quite an appreciable time unable to attend to their duties. Such a collision would naturally cause the boat to leak and to sink. In these newer Holland ships an automatic device causes the ship, when she has sunk to a certain depth, registered of course by automatic machinery, to start certain apparatus which empties the ballast tanks and starts the pumps which will empty the interior of the ship if it has become flooded. The result is that after a few minutes of this automatic work, whether the crew has sufficiently recovered to take part in it or not, the boat will rise to the surface.

This extraordinary invention is curiously reminiscent of the fact chronicled in earlier chapters of this book that the most modern airplanes are so built that should the aviator become insensible or incapacitated for his work, if he will but drop the controls, the machine will adjust itself and make its own landing in safety. Unaided the airplane drops lightly to earth; unaided the submarine rises buoyantly to the air.

In recent years there have been developed special ships for the salvage of damaged or sunk submarines. At the same time the navies of the world have also produced special submarine tenders or mother ships. The purpose of these is to supply a base which can keep on the move with the same degree of facility which the submarine itself possesses. These tenders are equipped with air compressors by means of which the air tanks of submarines can be refilled. Electric generators make it possible to replenish the submarine storage batteries. Mechanical equipment permits the execution of repairs to the submarine's machinery and equipment. Extra fuel, substitute parts for the machinery, spare torpedoes are carried by these tenders. The most modern of them are even supplied with dry dock facilities, powerful cranes, and sufficiently strong armament to repel attacks from boats of the type most frequently encountered by submarines.

There are, of course, many other special appliances which make up the sum total of a modern submarine's equipment. Electricity is used for illuminating all parts of the boat. Heat is supplied in the same manner; this is a very essential feature because the temperature of a submarine, after a certain period of submergence, becomes uncomfortably low. Electricity is also used for cooking purposes.

Every submarine boat built to-day is equipped with wireless apparatus. Naturally it is only of limited range varying from one hundred and twenty to one hundred and eighty miles, but even at that it is possible for a submarine to send messages to its base or some other given point from a considerable distance by relay. If the submarine is running on the surface of the water the usual means of naval communication-flag signals, wig-wagging or the semaphore, can be employed. The submarine bell is another means for signalling. It is really a wireless telephone, operating through the water instead of the air. Up to the present, however, it has not been sufficiently developed to permit its use for any great distance. It is so constructed that it can also be used as a sound detector.

Some submarines, besides being equipped with torpedo tubes, carry other tubes for laying mines. In most instances this is only a secondary function of the submarine. There are, however, special mine-laying submarines. Others, especially of the Lake type, have diving compartments which permit the employment of divers for the purpose of planting or taking up mines.

Disappearing anchors, operated by electricity from within the boat, are carried. They are used for steadying the boat if it is desired to keep it for any length of time on the bottom of the sea in a current.

From this necessarily brief description it can be seen readily that the modern submarine boat is a highly developed, but very complicated mechanism. Naturally it requires a highly trained, extremely efficient crew. The commanding officers must be men of strong personality, keen intellect, high mechanical efficiency, and quick judgment. The gradual increase in size has brought a corresponding increase in the number of a submarine's crew. A decade ago from 8 to 10 officers and men were sufficient but to-day we hear of submarine crews that number anywhere from 25 to 40.

In spite of the marvellous advances which have been made in the construction, equipment, and handling of the submarine during the last ten years, perfection in many directions is still a long way off. How soon it will be reached, if ever, and by what means, are, of course, questions which only the future can answer.