SUBMARINE NAV'IGATION. 239 



transportine: small submarines to Saig-on and performed the service 

 without difficulty. Whether this development of small portable 

 submarines will take effect or not remains at present an open question, 

 but there will be no mechanical difficulty either in the production of 

 the vessels themselves or in the means for lifting and carrying them. 

 M. Goubet worked out with complete success designs for vessels about 

 26 feet long and less than 10 tons displacement, with speeds of 5 to 

 6 knots, the trials of which have been very fully described, but French 

 authorities have not adopted the type and no decision seems to have 

 been taken to introduce it. In this country no similar action has 

 been taken, and our smallest submarines, weighing 120 tons, can not be 

 regarded as " portable." Indeed, some leading British authorities on 

 subnuirines have indicated that experience is adverse to the con- 

 struction of vessels in which not more than two or three men would 

 form the crew, and on that ground have condemned the construction 

 of these small submarines. They would necessarily be of slow speed 

 and very limited radius of action, while their efficient working would 

 depend upon the nerve and skill of only tw^o or three men working in 

 a very confined space. 



Progress in mechanical engineering and in metallurgy' has been 

 great since Bushnell constructed and used his first submarine in 1776, 

 during the war between the United States and this country. These 

 advances have made it possible to increase the dimensions, speed, and 

 ladius of action of submarines; their offensive powers have been 

 enlarged by the use of locomotive torpedoes, and superior optical 

 arrangements have been devised for discovering the position of an 

 enemy while they themselves remain submerged. But it can not be 

 claimed that any new principle of design has been discovered or 

 applied. From descriptions left on record by Bushnell and still ex- 

 tant it is certain that he appreciated and provided for the governing 

 conditions of the design in regard to buoyancy, stability, and control 

 of the depth reached by submarines. Indeed, Bushnell showed the 

 way to his successors in nearly all these particulars, and, although 

 alternative methods of fulfilling essential conditions have been intro- 

 duced and practically tested, in the end Bushnell's plans have in 

 substance been found the best. The laws which govern the flotation 

 of submarines are, of course, identical with those applying to other 

 floating bodies. When they are at rest and in equilibrium they nuist 

 displace a weight of water equal to their own total weight. At the 

 surface they float at a minimum draft and possess in this '' awash " 

 condition a sufficient free board and reserve of buoyancy to fit them 

 for propulsion. When submarines are being prepared for " diving " 

 water is admitted to special tanks, and the additional weight in- 

 creases immersion and correspondingly reduces reserve of buovancy. 

 In some small submarines comparative success has been attained in 



