674 EEPOiiT— 1882. 



in steam cylinders 4j in. diameter, by 7 ft. stroke. This system has given excellent 

 results in experiments at Portsmouth. 



In the later Danish and Italian boats the troughs have been replaced by tubes 

 from which the torpedoes are ejected by compressed air stored in reservoirs and 

 admitted into the tubes behind the torpedoes. Besides other advantages possessed 

 by the air-impulse system, so long as the reservoirs and torpedoes are charged, the 

 boats may be used independently of steam being up in their boilers, and v^'ould thus 

 serve as so many launcliing tubes on the ships to which they are attached. 



Coming to the first-class boats, these, in general construction, hull, engines, 

 and boilers, resemble the second-class type, but are, of course, on a larger scale. 



The dimensions of most of the Admiralty first-class boats are : — Length over 

 all, 87 ft. ; beam, 10 ft. 10 in. ; draught of water, 5 ft. 2 in., with a displacement 

 of 32"4 tons. That, however, represented by the model was 90 ft. 6 in. over all, 

 by 10 ft. 10 in. beam, and, like the rest, was fitted with engines having cylinders 

 121 and 20| in. respectively in diameter by 12 in. stroke, which, on trial, gave 

 indicated horse-power 469 at 443 revolutions per minute and speed 21f knots 

 per hour. 



The Italian type of first-class boat is 100 ft. long, 11 ft. 8 in. beam, and has a 

 draught of water of 5 ft. 5 in., and 34"5 tons displacement. The cylinders are also 

 somewhat larger, being 13^ and 22 in. diameter, respectively ; the boUers are also 

 larger, having a grate surface of 19'4 sq. ft., and a heating surface of 698'8 sq. ft. 



The subdivision of the hulls by bulkheads and half-bulkheads is similar to that 

 in the second-class boats, and ejectors are similarly fitted. The six ejectors of the 

 Italian boats are alone capable of pumping out the whole displacement in 7J 

 minutes. In the Italian boats all the pumps are driven by a separate engine, and 

 the main engines are devoted entirely to propelling the boat. 



The English first-class boat carries three 14-in. Whitehead torpedoes, two in 

 transporting carriages on the sides of the vessel, and one in the torpedo gun, as 

 it has been called, on the forward deck. By means of this gun, which can be 

 elevated or trained like an ordinary gun, the torpedo may be projected ahead or on 

 either side. Hence there is no necessity for attacking bows on, as in the second- 

 class boats, or for stopping immediately before or after the discharge. In the 

 earlier examples, the torpedo was ejected by an air-impulse gear ; now, a cartridge, 

 containing a slow-burning powder, is used. 



The objections to this system are — that the boat cames to the attack only one 

 torpedo ready to be ejected ; that the gun cannot be reloaded without retiring, or 

 else exposing the men engaged in the operation to great danger ; and the reserve 

 torpedoes are liable to be hit by Nordenfeldt buUets or Hotchkiss shell, either of 

 which would certainly disable them, and might even cause a destructive explosion. 

 The Italian and Danish boats carry four 14-in. "NVliitehead torpedoes, arranged 

 as in their second-class boats, that is — two in the ejecting tubes, and two in the 

 loading troughs, immediately behind, but in this case all are completely enveloped 

 in the hull of the boat. To reach them, a bullet would have to penetrate 35 in. of 

 plating, and | in. of tube, in all ^t: in. The torpedo is ejected by an air-impulse 

 gear, similar to that already described, the air for which and for the torpedoes is 

 supplied at a pressure of 70 atmospheres by a small air-compressing pump in the 

 engine-room. 



A permanent lifting gear, similar to that of the second-class boats, has recently 

 been fitted to these boats, and the first two of them, weighing about 28 tons each, 

 were shipped in an hour and a half 



The largest torpedo-boat built by the author's firm, and the large.st yet afloat, 

 is that lately supplied to the Danish Government. She is 110 ft. long by 12 ft. 

 beam, draws 6 ft. 3 in. of water, and has a displacement of 52^ tons. Her speed 

 on the three hours' trial was 20 knots per hour, and she carries coal (10 tons) to 

 steam 1,200 knots at a speed of about 11 knots. Her armament consists of four 

 15-in. Whitehead torpedoes, 19 ft. in length, and carrying a charge of 80 lbs. of 

 gun-cotton. The Danish Government propose to caiTy this boat and others of her 

 class from point to point of the coast on their railways, so that an en»my would 

 know nothing of their movements or where to expect them. 



