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



Table VI. 



U. S. "A"' English "D" French Pin- French Bru- 

 class class viose class tnaire class 



Length 153' 4" 150' — — 



Surface displacement, tons 389 550 400 4CK) 



Submerged displacement, tons 519 615 550 550 



Engines Diesel Diesel Steam Diesel 



Horse-power, surface 900 1,200 — 850 



Speed, surface, knots 14 14 12.3 13 



Speed, submerged, knots 10.5 8-9* 8 9 



Armament, torpedo tubes (internal) .... 4 3 I I 



Exterior launching apparatus — — 6 6 



The offensive submarine as it now actually exists is exemplified in its highest 

 development by the boats of 650 to 750 tons surface displacement, the character- 

 istics of which are given in Table III. This is not to say that some boats of 

 smaller displacement are not playing the offensive role in the European war. In 

 fact, the records appear to show that, under the conditions actually existing in 

 Europe, smaller types can and are being employed usefully for this purpose. 



In closing this part of the subject, the author wishes to emphasize the fact 

 that the discussion has so far been limited to the submarines actually in active 

 service to-day. The classifications made are admittedly not rigid. The limits to 

 displacements mentioned in connection with the various classes are derived from a 

 study of the actual facts from the point of view of the classification adopted. 

 The primary object has been to outline briefly modern practice in submarine con- 

 struction, particularly with reference to the smaller units, the design of which, 

 owing to the present advanced state of engineering development, is now fixed 

 almost entirely by military considerations. 



THE SUBMARINE OF TO-MORROW. 



Enough has already been said to indicate that, up to displacements of 750 tons 

 and speeds of 17 and 11 knots, the designs of "the submarines of to-morrow" will 

 be fixed, not by engineering limitations (as in the past), but by military (including 

 financial) considerations. 



Any opinion as to whether the very small harbor or local defense type is 

 destined to be perpetuated lies outside of the scope of this paper, but it may not 

 be out of order to venture a guess in the negative. At any rate, if this type is 

 found in future naval programs, that fact will constitute a marked exception to 

 the ordinary history of naval development. On the other hand, the coast defense 

 and offensive types are sure of perpetuation. In fact, their value is now so fully 

 recognized as to make it certain that present and future naval programs must in- 



*Doubtful. 



