886 Transactions of the American Institute. 



By the action of the wheel, we are enabled to throw the boat up 

 alongside the dock, saving the use of capstans, and the employment 

 of a large number of hands, and doing the work with more facility, 

 the power of the engine, acting through the wheel, being more 

 effective for that purpose than the strength of men acting through a 

 capstan. By reversing the direction of the wheel's force, the stern 

 can be thrown from the dock, and the vessel changed side for side, 

 when it is desired to take on cargo from the opposite side. The 

 stern of the vessel can also be thrown to or from the dock, greatly 

 facilitating its departure. 



In the capacity of a tug boat, towing a vessel of larger size, we 

 are enabled to produce a direct side movement of both vessels, 

 without auy turning of either. This movement other propellers 

 are incapable of performing, and would be of gi-eat value to tugs, 

 more especially in such localities as Chicago river or Buffalo creek, 

 where this side movement is often required, and there is not room 

 to " straighten out." 



ROOM. 



The machinery for this propeller occupies less room than that of 

 ordinary propellers, and it leaves it in larger apartments. The 

 engine is located aft in an unusual part of the vessel, which is 

 divided into only two apartments by the boiler, while in the screw 

 it is divided into three apartments by the boiler and engine, which 

 occupies the space most required for carrying purposes, and a 

 large share of extra space is occupied by the shaft of the propeller. 



"WEIGHT. 



Eespecting the weight of the machinery, the wheel being made of 

 steel is much lighter than a screw made of cast iron, where .both 

 possess the same strength. And there is a further saving, by the 

 simplicity of the engine and by dispensing with the ponderous 

 shaft, which extends a good part of the length of the vessel, when 

 provided with a screw. 



DRAUGHT. 



It also has the advantage of the screw in draught of water. As 

 much propelling power can be obtained in four feet of water as in 

 eight feet of water with the screw. By this means we are enabled 

 to construct boats with light draught, to which can be imparted a 

 high speed; and to navigate shoal water where the screw would be 

 impracticable. 



