120 



FIG. 3. 



produced upon the floating bodies by sails at different angles 

 and of different constructions, will be seen by submerging the 

 sails, and passing them through the water in the direction of 

 the axis. If the sails be formed of the construction hereby 

 recommended, they will revolve without materially disturbing 

 the particles of floating matter ; but in proportion as the form 

 differs from this principle, there will be more or less disturb- 

 ance of the water, and commotion amongst the bodies floating 

 therein. 



These experiments in water also clearly establish the law 

 which governs the velocity of revolving bodies, acted upon 

 by fluids on this principle. For let a b, Fig. 3,* represent 

 the plane in which the wheel rotates 

 upon its axis, and the oblique lines ^[ 

 drawn from b, and terminating in the 

 line A c, be the ano^les which the 

 extremity of the vanes of variously 

 formed wheels make with the plane 

 of rotation ; then supposing a b also 

 to represent a line of the same length 

 as the circumference of the wheel w. 

 Fig. 4, and the angle a b e be that 

 which the extremity of the vane or 

 sail forms with the plane of rotation, 

 the wheel upon being moved through 

 the water in the direction of the axis, 

 would make one revolution in the dis- 



riG. 4. 



■UlliwHlllll 



tance a e, or four in that of its own circumference. If 



* This diagram, Fig. 3, presents a convenient method of ascertaining the proper 

 angles to be given to vanes or floats at any required distance from the centre of 

 the wheel, the angle at any one distance being given. 



The line a b represents the radius of the wheel, b d the axis, and a C the 

 periphery of the wheel, the lines 1, 2, 3, 4, 5, divide the radius into six equal 

 parts. The angle which the vane is to have at any given distance from the 

 centre of the wheel, must be set off from the point b, on the line b c, through 

 which an oblique line should be drawn until it intersects the vertical line at the 



