202 THE SUBMARINE OF TO-DAY AND TO-MORROW. 



existence (the result of gradual engineering development), which, though still use- 

 ful, are not likely to be duplicated in the future. 



At this point, a brief survey of what may be termed the mechanical develop- 

 ment of the submarine seems desirable. The growth may perhaps be best illustrated 

 by a comparison of the characteristics of one of the first successful boats with 

 those of a recent type. The principal characteristics of these two designs designated 

 as "A" and "B" are set forth in the following (Table I) : — 



Table I. 



Type "A," igoo Type "j9," igj4 



Length 53' 10" 230' 6" 



Beam 10' 3" 21' 6" 



Surface displacement, tons 67 663 



Submerged displacement, tons 75 912 



Horse-power, surface 50 2,000 



Speed, surface, knots 6 17 



Horse-power, submerged 50 980 



Speed, submerged, knots 51^ 10^ 



Radius action, surface, knots 200 3,000 



Number torpedo tubes i 8 



At the date of the production of type "A," type "B" would have been an utter 

 impossibility for lack of suitable propulsive machinery. As the equipment in each 

 case represents the highest development of the corresponding period, the compara- 

 tive figures given in Table H below are of interest as showing the improvement re- 

 sulting from ten years of step by step development. 



Table H. 



Type "/?," IQOO Type "B," igi4 



Horse-power main engines 50 2,000 



Pounds per horse-power 78 48 



Fuel consumption, pounds per horse-power .74 .50 



Horse-power electric motors 50 980 



Pounds per horse-power 57 48 



Pounds per horse-power of storage battery 909 216 



As noted above, type "B," for the design of which the author is responsible, has 

 been selected as fairly representative of the best results actually achieved to date in 

 the mechanical development of the submarine. The representative character of the 

 figures will be corroborated by an examination of the characteristics of the contem- 

 porary vessels in the English and German navies, viz., the English "E" class and the 

 German "U-21 to U-32." Table HI below gives the most important characteristics 

 of these three designs, as well as such data as are available with respect to the Ger- 

 man class "U-33 to U-42," which have been commissioned since the outbreak of 

 the war. 



