218 Mr Middleton, On the [Nov. 24, 



Class (a) . The boats of this form are intended for speed, they 

 are of a shape which somewhat resembles a cigar and may be called 

 "fish" boats. Moreover these boats are furnished with two lateral 

 fins, two — or one — screw propellers, at the stern, and a dorsal and 

 ventral fin for guiding them, &c. &c. These boats are intended to 

 remain a more or less period under water; but even those capable 

 of being submerged for a very considerable time are yet supposed 

 to come to the surface and be used as super-marine boats when 

 cruising. When submerged, the boats simply 'fty' in the sur- 

 rounding fluid: just as the Guillemot can, and does fly in water, or 

 a bird in the air. The boats of Class (a) are armed with guns 

 capable of being fired against an object under water: or the guns 

 can be fired when the boat is above water, as when attacking a 

 fort on land. However, such form of attack would rarely be 

 adopted as the boat has only to be submerged, when it can be 

 quietly run past the shore batteries without their being able to 

 fire a shot in the defence of the channel which they were intended 

 to guard. All the boats of Class (a) are fitted with apparatus for 

 removing submarine mines, torpedoes, &c. &c. ; but such operations 

 are better performed by the boats of Class (6), of which a few 

 words shall be said later. When the boats of Class (a) are in- 

 tended to attack fleets of ironclads (as at present constructed), a 

 large part of their time is taken up in cruising, which they do with 

 their funnels and a small portion of their hull [hardly more than 

 the "conning tower"] above water. When ironclads are sighted 

 and the boat is to be taken "into action," it is submerged some 

 ten, or more, feet. And (its funnels having been previously with- 

 drawn into the 'hull' of the vessel,) its submarine engines are set 

 going. 



Because there is no "exhaust" thrown outside of the boat, 

 there is no increase of "back pressure" on the pistons owing to 

 depth; and indeed the boat can be worked at any depth less than 

 that at which its hull would be crushed by hydrostatic pressure. 

 The time that the boat can remain under water is several hours: 

 but the time that she can run at full speed under water is much 

 less than the period she can remain submerged with her crew, if 

 her engines are not working. In all the boats, however, the time 

 of submersion when running at full speed is sufficient to enable 

 them to get out of gunshot of a stationary foe. [And the chances 

 of an enemy steaming exactly parallel to the line of the submarine 

 boat's motion under water, so as to be along side of it when it is 

 forced to come to the surface — I say the chances are not very great : 

 so the ironclad, if it does move, is just as likely to move away 

 from the submarine boat as towards it, this consideration of the 

 time to get out of gunshot of a stationary foe has determined the 

 construction, &c. &c. of the submarine engines.] Usually, on 

 account of the extremely small surface which the boat exposes 



