SUBMARINE VESSELS 



Such performances as these are thought-provoca- 

 tive, to say the least. Submarine boats that can hit the 

 target without being detected, go on cruises unattended 

 for more than a thousand miles, and remain submerged 

 for more than a day and a half, must be classed as 

 efl&cient engines of warfare. 



Since the submersible is designed to spend most of 

 its time on the surface of the water like an ordinary 

 boat, it must have considerable buoyancy, but it must 

 also have some means of getting rid of this buoyancy 

 quickly when submergence is necessary. The sub- 

 marine proper has only from five to eight per cent, 

 buoyancy, while some of the submersibles have twenty- 

 five per cent, or more. With such boats of the ordi- 

 nary size some fifty tons of water must be admitted 

 before bringing them to a condition in which they can 

 be submerged ; but this can be done very quickly. One 

 of the submarines of the U. S. fleet in an actual test 

 filled her ballast tanks and dived to a depth of twenty 

 feet in four minutes and twenty seconds. 



It is not impossible that the recent triumphs in aerial 

 navigation may have an important bearing on the use 

 of submarines in future wars. It is well known that 

 large objects when submerged even to a considerable 

 depth are discernible from a height in the air directly 

 above them. It is quite possible, therefore, that swdft 

 aeroplanes circling about a fleet of war vessels might be 

 able to detect submarine boats when these boats were 

 near enough the surface to use their periscopes. If so 

 it might be possible for the aeroplanes to drop torpedoes 

 upon the submerged boats without danger to them- 



[117] 



