564 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



forth the vessel which, with sufficient weight, has the greatest 

 speed, and can change her course most speedily, must infallibly 

 defeat her opponent by crushing in her sides. The plan which 

 he exhibited, unless his judgment was warped by his partiality 

 for the inventor, combines these requisites in the highest degree. 

 It is driven by two propellers, one on each side of the vessel, and 

 may therefore, by the application of sufficient power, receive a 

 much higher speed than can be given by a sigle propeller. Placed 

 amidships, tliese propellers can give the vessel a motion around 

 an axis in her midship section, while by two propellers at the 

 stern, the axis of motion is in the stern-post. The act of wearing 

 will, therefore, be performed, all other circumstances being equal, 

 in half the time. The model I exhibit has been laid before the 

 Navy Department, and has received a favorable report. The 

 inventor is Edward S. Renwick, of tliis city, and the description 

 of the vessel is as follows : 



Length of vessel. _. 400 feet. 



Breadth of beam _ 60 " 



Depth of hold ' 37 " 



Draught of water 22 1 " 



Speed per hour at least 18 miles. 



The form and arrangement of this vessel are shown in the 

 accompanying sketches : Fig. 1 representing a side view of the 

 vessel ; Fig. 2, a plan of it at the lower edge of the armor plates, 

 four feet below the water line ; Fig. 3 being a transverse section 

 at the engines, and Fig. 4 a plan of a fragment of the vessel at 

 the engines. The objects of the projector were, to obtain great 

 speed, a heavy armament, protection of the guns against shot, 

 and a capacity to turn the vessel as if upon a pivot ; also to form 

 the vessel in such manner that she could be used as a ram. In 

 order to attain these objects, the length, e f, below water, was 

 made sufficient to obtain fine lines at the bow and stern, as shown 

 in Fig. 2, and the bow and stern above water were cut back, as 

 shown at Fig. 1, to reduce the weight of the armor plates to the 

 smallest possible quantity compatible with the protection of the 

 battery. The bow and stern above water thus present the form 

 of a half cone with the butt at the central battery. This plan 

 relieves the bow and stern of strain of heavy weights, Avhere the 

 displacement, from the fineness of the water lines, is unequal to 

 the load placed over them, and at the same time furnishes a long 

 heak which projects under water. 



