PERPETUAL MOTION 49 



may fall in its descent, it would turn the screw round, 

 and by that means convey as much water up as is required 

 to move it ; so that the motion must needs be continual 

 since the same weight which in its fall does turn the wheel, 

 is, by the turning of the wheel, carried up again. Or, if 

 the water, falling upon one wheel, would not be forcible 

 enough for this effect, why then there might be two, or 

 three, or more, according as the length and elevation of the 

 instrument will admit; by which means the weight of it 

 may be so multiplied in the fall that it shall be equivalent 

 to twice or thrice that quantity of water which ascends ; 

 as may be more plainly discerned by the following diagram 

 (Fig. 10): 



"Where the figure LM at the bottom does represent a 

 wooden cylinder with helical cavities cut in it, which at AB 

 is supposed to be covered over with tin plates, and three 

 waterwheels, upon it, HIK; the lower cistern, which 

 contains the water, being CD. Now, this cylinder being 

 turned round, all the water which from the cistern ascends 

 through it, will fall into the vessel at E, and from that 

 vessel being conveyed upon the waterwheel H, shall conse- 

 quently give a circular motion to the whole screw. Or, if 

 this alone should be too weak for the turning of it, then 

 the same water which falls from the wheel H, being re- 

 ceived into the other vessel F, may from thence again 

 descend on the wheel I, by which means the force of it 

 will be doubled. And if this be yet insufficient, then may 

 the water, which falls on the second wheel T, be received 

 into the other vessel G, and from thence again descend on 

 the third wheel at K ; and so for as many other wheels as 

 the instrument is capable of. So that besides the greater 

 distance of these three streams from the center or axis by 



