340 THE SCIENTIFIC PAPERS OF 



centrifugal pump he bad no doubt, because, as pointed out in the 

 paper, the water was not diverted from its course by abrupt changes 

 of direction, and therefore very little power could be lost by eddies. 

 The height of lift, as shown in the paper, was readily determined ; 

 for if the velocity of the pump were given, the height was known 

 to which the column of water would rise to be in equilibrium, and 

 half that height would in all probability produce the greatest 

 amount of useful effect. It occurred to him that this pump 

 would be extremely useful for lower lifts than other rotary pumps 

 were generally employed for. As a turbine also he thought it 

 would have certain advantages, inasmuch as the water in passing 

 through a large wheel of that kind would be very little mutilated, 

 and there would be very little loss in the way of eddies, provision 

 being made for the water to expand into a larger channel before 

 its final discharge, and it appeared to him that the construction 

 admitted of almost unlimited extension in dimensions or number 

 of turns of the helix, so as to utilize large amounts of water-power. 

 He should like to know whether it had been so applied and with 

 what results. It appeared to him also that if ever the idea of ship 

 propulsion on Ruthven's plan of water jet should be taken up, 

 this pump would particularly recommend itself as a propeller for 

 such a purpose, because the water would not be taken into the 

 ship in one direction and discharged in another after having its 

 motion changed or even reversed, but it might be taken in at the 

 front and expelled toward the stern in the same line, passing in a 

 continuous course through the helical channel of the propeller. 

 These were applications that occurred to him on first becoming 

 acquainted with the helical pump ; and he hoped to see many 

 applications made of the principle, which appeared to him to be 

 very novel and ingenious. With regard to the blades of the 

 paddle-wheel, it had naturally occurred to him at first that it 

 would be better to place these at an inclination across the face of 

 the wheel, so as to be exactly at right angles to the curve of the 

 helix, and this he thought would be the proper position 

 theoretically ; but as that inclination would produce an end 

 pressure on the axis of the rotating wheel which would probably 

 do as much harm as would counterbalance the increased efficiency 

 obtained, it was no doubt preferable to set the blades parallel to 

 the axis of the wheel, as shown in the drawing. 



