In the early stages of the war, when military and naval aviation was trying to adopt peace-time theories to war-time facts, Great Britain attempted to hunt the German submarines with aeroplanes, or hydroaeroplanes; but the method had its serious draw-backs. The aeroplane is of necessity a fast traveling machine; it must make at least forty miles an hour to be able to stay aloft. Whizzing through the air at such speed is not conducive to a careful scrutiny of the surface of the water below, necessary in order to detect the vague, dim outlines of a submerged submarine. At first the pilots of naval aeroplanes had considerable success in locating the submarines, and Germany lost quite a few of them, before the reason was discovered. Some one in Great Britain announced that it was easy to locate a submarine from an aeroplane by the peculiar reflection in the sunlight caused by the fine film of lubricating oil on the surface of the water. As soon as this "tip" was communicated to Germany, submarines discontinued the use of oil for lubrication, employing instead deflocculated graphite. The fuel oil used in the Diesel engines for propulsion on the surface is so thoroughly consumed and the exhaust now is so free of oil that an oil film as an indication of submarine proximity is no longer trustworthy. Besides, the submerged boat might be a friendly one, a fact which was borne upon the British authorities on two separate occasions when scouting aeroplanes reported submarines near, and speedy motor boats rushed to the attack. In one case the British submarine is reported to have been rammed, and in the other—so the story goes—the commander of the submarine liberated a little buoy attached to the outside of the boat, which rose to the surface and informed the watchers above that "a friend is down below—not an enemy!"
The system followed now in the locating and possible destruction of German submarines in the Channel and North Sea by French dirigibles is as follows: The airships, chiefly of the Astra type, travel at a height of not more than 500 feet above the surface of the ocean, while the observers constantly sweep the water within a radius of half a mile with their glasses. Usually the airships are sent ahead at low speed in spirals, or in a series of curves which enable them to cover every square mile of watery area below. As soon as one of these airships sights a submarine traveling submerged, it flashes the news by wireless to destroyers which at the time may be fifty or more miles away, and in the meantime endeavors to remain directly above the submerged boat. Soon the destroyers arrive and, following the direction of the airship, can ram or sink the submarine with almost certain success. The French admiralty claims to have accounted for a number of submarines by this method, but has found that the scheme no longer will work. The German naval department, learning of the airship patrol, has given its submarine commanders orders to travel at great depth during daylight hours in the Channel and the southwestern section of the North Sea, or to go to sleep on the bottom where the sea is too shallow. In the evening the boat makes its escape from the dangerous neighborhood.
The third field of action of airships—devastating hostile countries—is the least valuable, although perhaps the most spectacular of the activities of airships of the Zeppelin type. The damage caused by the numerous Zeppelin raids over England, for instance, is a subject of so much dispute that a true appreciation of their value cannot be formed at present. While the German official bulletins repeatedly declare that great material damage was done by the bombs to military establishments, factories, harbor works, etc., the British statements dwell more upon the number of noncombatants who were killed, and deny the infliction of any material damage.
Information of this kind is considered legitimate secrecy and it is only when files of the British local and trade papers are examined that an inkling of the real damage is obtained. Fires, boiler explosions, railway traffic suspensions, and similar highly suggestive items fill the columns of the papers, after every one of the Zeppelin raids. On only one occasion, February 2, 1916, has the British War Office admitted serious military damage in its official communication. This communication was issued after exaggerated reports of the damage caused had appeared in the German and neutral press, covering the Zeppelin raids of January 30-31, 1916, and February 1, 1916, and admitted officially the following: Bombs dropped totaled 393; buildings destroyed: three railway sheds, three breweries, one tube factory, one lamp factory, one blacksmith shop; damaged by explosions: one munition factory, two iron works, a crane factory, a harness factory, railway grain shed, colliery and a pumping station. "One of the spectacular incidents of this raid was the chase of an express train by the Zeppelin, the train rushing at its utmost speed of seventy miles an hour into a tunnel, disappearing just as the first bombs began to drop. The train remained in the tunnel for more than an hour, waiting for the Zeppelin to fly away!" The official figures of killed and wounded in this raid are given as sixty-seven killed, and 117 injured.
During the month of July, reports of the new German super-Zeppelins began to appear in British reports, and a number of neutral correspondents endeavored to obtain authentic data concerning them. Conflicting descriptions arrived from many sources, and it was not until a Swiss reporter, equipped with extremely powerful glasses, watched the trial flights of two of these super-Zeppelins above Lake Constance, that fairly reliable information could be compiled.
One of these airships leaves Friedrichshafen every week for duty in the North Sea, and the factory on the shore of Lake Constance expects to be able to complete five machines every month after July, 1916. The super-Zeppelin has two armored gondolas, without a visible connection, although it is highly probable that such communication is provided for within the outer envelope. Each gondola carries six machine guns and, in addition, two quick-firing guns, as well as an aerial torpedo-launching device, which was first used in the extensive air raids on England in the last week of July.
The super-Zeppelin contains approximately 1,000,000 cubic feet of gas and has a capacity of ten tons useful load. Of this load, about four tons can be composed of bombs or other munitions, the remainder being needed for fuel, machinery, and the crew, as well as ballast and provisions. The gross weight of a fully equipped and loaded super-Zeppelin is thirty tons, or roughly, 60,000 pounds. The envelope, which heretofore has been painted gray with liquid aluminum paint, now is impregnated thoroughly with finely divided metal, by means of the Schoop metal-coating process, which is heralded as one of the most far-reaching improvements in aerial navigation. By its means the airship envelope is made absolutely impervious to atmospheric influences.
For its protection against antiaircraft fire the new super-Zeppelins carry apparatus in each gondola, producing artificial clouds of such size and intensity as to envelop and shroud completely the entire airship, rendering it absolutely invisible from below. While this cloud expands and gradually grows thinner, the airship rises rapidly in a vertical direction, speeding away while under protection of the self-made clouds.
The motors of the latest Zeppelins weigh only 595 pounds each, although developing 240 horsepower, which means that one horsepower is developed for every three and three-quarter pounds of metal used. They are fitted with twin pumps, double jet carburetors, and are usually operated on mixtures consisting of one part benzol with one part alcohol.[Back to Contents]