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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