Page:Popular Science Monthly Volume 91.djvu/659

 Popular Science Monthly

��Vol. 91

No. 5

��239 Fourth Avenue, New York City

November, 1917

��$1.50 Annually

��The Gun-Buoy for Repelling Submarines

It has living quarters for four, telephone connections, periscopes and a rapid-fire gun — all the modern marine conveniences

��A SERIES of huge buoys, each of which carries a gun and on each of which four men can live for many days, is the latest solution which has been offered to cope with the submarine menace.

As the picture on the opposite page shows, each buoy has an upper deck on which a three - inch rapid - fire gun is mounted, living quarters below the gun- deck, a tank below the living quarters, which tank is to be filled with water in order to sink the buoy, and finally, a cylindrical compressed-air tank at the bottom. The buoy itself is about sixteen feet in diameter and about twenty feet deep from the gundeck to the top of the compressed-air tank. At the bottom of the compressed-air tank is a cable drum and winding gear. The anchoring cable is wound around this drum. When the buoy is to be rapidly submerged, its sinking can be hastened by winding up on the drum gear, the extra downward pull assist- ing the water admitted into the submer- gence tank. A hand gear is provided in the living quarters to facilitate the winding up of the mooring cable.

The buoy is equipped as completely as a boat or as a submarine itself. It has a periscope, which can be used when the gun deck is just awash; a wireless outfit; telephone connections with a land station; a microphone for picking up the hum of a submarine's motors under water, and a small gasoline engine with attached air compressor, which is stored in a watertight compartment and which serves the purpose of filling the compressed-air tank.

A whole series of these buoys is to be used. They are connected by a telltale net of very light construction, the meshes of which are about twenty feet square. The nets are to be made in units measuring forty feet by two hundred. Light bamboo

��poles suspend the nets in the water, the bottom pole being weighted so as to keep the unit upright. The upper bamboo pole is connected with a little float which is shown in the detail drawing on the opposite page. The float carries a telltale flag and an incandescent lamp, the one to be used by day and the other by night. As soon as a submarine strikes the net, the flag is thrown up and the light flashes.

Each little float is attached to the top of each net unit. The connection between the float and the net is such that the slightest tension upon the part of the net will destroy the connection. A line leads from the net unit to the little float through a watertight tube and to a drum on which it is reeled. As soon as the submarine strikes the net unit, the float rises and the line is unreeled. When the whole line is unreeled a latch attached to the drum is released and that, in turn, unlocks the flag, which is forced up by a spring. The pole of the flag throws a knife switch so that the battery is simultaneously placed in circuit with the electric light.

The buoys are in direct communication with one another as well as with the main- land and the patrol fleets so that they are able to give instant warning of the presence of a submarine within their radius of action. Normally each buoy would float just above the surface with its hatch open. One man would be stationed on deck as a lookout; another would operate the wireless apparatus; a third would stand ready to perform any necessary operation; a fourth man would be sleeping.

The cost of making the buoys and net units is small compared with the building of destroyers and submarine chasers and steel nets. Moreover, they can remain at their stations for a far longer period than a patrol fleet can remain at sea.

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