566 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



of seventy-eiglit inches diameter, and three feet nine inches 

 stroke ; six boilers, each having six furnaces on a side, giving a 

 collective grate furnace of twelve hundred and twenty-four square 

 feet ; two propellers, each seventeen feet in diameter and thirty- 

 two feet pitch. 



This vessel has about one-half more power than the Stevens 

 battery, while from the simplicity and compactness of the engines, 

 the machinery occupies much less space. The propellers are sit- 

 uated at the strongest part of the vessel, instead of overhanging 

 at the stern, where they would exert a tremendous strain upon 

 the narrow part of the vessel. In order to permit the propeller 

 blades to turn freely, a slight indentation is formed in the side 

 of the vessel ; and in order to direct the water in this indenta- 

 tion around the tubular propeller shaft, horizontal wedge-formed 

 chambers, s s, are placed in between the propeller shaft and the 

 vessel. When the vessel is in port, the propellers are protected 

 from injury by contact with the dock, by hanging a removable 

 skeleton guard upon each side of the vessel, similar to the guard 

 beams which protect a paddle wheel. The vessel has a complete 

 berth-deck under her gun-deck, for the crew, and ample space 

 for stores in the compartments, which are in advance of and 

 behind her boilers. The ventilation of the vessel is effected by 

 fan-blowers, driven by separate donkey engines, and the foul air 

 and smoke from the guns escape through a longitudinal shot-proof 

 grating in the spar deck at o. Fig. 3. The spar deck is plated 

 with iron like the sides, and is surrounded by a wooden bul- 

 wark, to keep off the sea. . The projector does not pretend to be 

 the first who conceived the idea of side propellers, but he claims 

 to be the first who has succeeded in arranging submerged side 

 propellers, and applying power to them in a practically useful 

 manner ; and that he obtains all the advantages that accrue from 

 the position of paddle wheels near the longitudinal centre of 

 the vessel, with the advantages that result from the use of sub- 

 merged propellers, without the defects of either system. 



If 15-iuch guns can be procured, the vessel is to be armed with 

 them, a smaller number being used ; and if it be deemed expe- 

 dient to protect all the guns by revolving towers, the sloping 

 sides of the vessel above the gun deck may be removed, and six 

 revolving towers put in their place. But as a vessel with towers 

 cannot fire more than two guns in line with the keel, and as this 

 vessel can do the same, wnth the capacity to turn rapidly to fire 



