866 heport— 1892. 



3. The Utilisation of the Energy of Flowing Wafer. Descriptio7i of the 

 Purdon-Walters Motor. By Messrs. Purdon and Walteks, Westminster. 



The motor, which was illustrated by the cartoons exhibited, is designed to 

 convert the energy of tiowinir water into mechanical power for the purpose of 

 driving electric, pumping, grinding, and other plant. 



The machinery of the motor is carried on a pontoon, below which is a lower 

 deck or platform attached to it by uprights. When at work the motor is moored 

 at right angles to the direction of the current, and adjusts itself automatically to 

 the varying levels of flood or tide. The lower platform covers in the moving parts 

 and provides for the motor taking the ground without damage in shallow water, 

 and even being worked in that condition. 



The mechanism acted upon by the water consists of blades fixed at even 

 intervals to an endless chain passing over two vertical end wheels, the links of the 

 chain gearing with flat .surfaces provided on the wheels. The bearings for the 

 wheel shafts are placed at such a level on the pontoon that half the chain and 

 blades, controlled by fixed guiding rollers, are submerged in the water, while the 

 other half are suspended in the air. 



The back portion of the pontoon is constructed with a watertight deck inter- 

 po.sed between the end wheels and the upper and lower parts of the chain, so that 

 when motion is imparted to the chain the blades which are submerged have a clear 

 passage through the water between the lower platform and the pontoon, and 

 return in the air above it. The remaining portion of the pontoon for carrj^ing the 

 gearing and machinerj' to be driven is in the form of an open barge, covered with 

 light shedding where required and boarded up fore and aft, outside the end 

 wheels, from the lower platform, to protect the blades in the water and to permit 

 of the motor being towed. 



The space between the pontoon and lower platform through which the current 

 has to pass from the front of the motor to the blades at the back is in the form of 

 a bell mouth, contracted laterally by means of curved wing vanes placed at each 

 end, and vertically by the inclination of the bottom of the pontoon and the lower 

 platform. 



In this space the current i.s diverted into the line of action of the blades, at 

 right angles to the stream, by means of curved guide vanes ; and the blades are 

 also curved to receive the pressure and allow of a free escape of the water into the 

 0]ien stream beyond. The whole arrangement is in fact that of the well-known 

 turbine rod. 



The bell mouth has the eff"ect of concentrating the energy of a large sectional 

 area of stream at a higher velocity than its natural flow on a comparatively small 

 blade area, the advantage obtained being that the weight of the moving chain and 

 consequent friction is considerably reduced, and the speed of the chain increased. 



The action of the machinery impelled by the current is as follows : — 



The current impinging on the blades forces those in the water forward with 

 the chain which revolves the end wheels and carries round the blades each in turn, 

 to be submerged and acted upon by the water. One of the end wheels is provided 

 with .spur gearing revolving a second motion shaft, from which any higher speed 

 can be obtained by the employment of pulleys and belting. 



The energy of a stream varies as the cube of the velocity, and maybe expressed 

 by the formula 



^ ~ Q, v^ = ft. lbs. per second, 

 9 



where G = weight of 1 cubic foot of water. 

 ^ = acceleration of gravity. 

 St = sectional area of the stream in feet. 

 V = velocity of stream in feet per second. 



Assuming a pontoon 40 feet long with a sectional area of 151 '6 square feet, 

 where the water enters the bell mouth opening, and that the motor shows an 



