2ti8 the effects of water on machinery. Oct, i: 

 tion to the velocity with which the water moves ; 

 but when water is made to descend on an inclined 

 'plain, towards a mill wheel, its velocity encreases 

 every inch it moves forward, so as to be much great- 

 er at the bottom of the spout, where it reaches the 

 wheel, than at the top of it ; and consequently the 

 depth of the fheet of water is much lefs where it 

 reaches the wheel than it was at the top of the 

 spout. 



This being understood, let us now suppose, that 

 in a trough of one foot diameter, and where the 

 A- A's are, by consequence, of the same length, such a 

 stream can be commanded as to fill the trough at the 

 top of the spout, so as to be on an average six inches 

 deep ; on a very moderate fall, that fheet of water 

 where it reaches the wheel would not be four inches, 

 (if tolerably great it would not be two inches.) Now 

 if we suppose the interval between the A A's and 

 the trough to be no more than half an inch, it would 

 follow, that one eighth part of the dead "weight of the 

 water would be lost. If it were one inch, which is 

 no uncommon case, the lofs would amount to one 

 fourth part of it. 



If, with a view to improve this machinery, the 

 trough fnould be widened, and the A A's. lengthened 

 to two feet, the consequences would plainly be these : 

 ■the depth of the water at the top of the spout would 

 now only be three inches instead of six, and of couxse 

 the thickne fs of the ftieet, where it reaches ihe whee L 

 would be only two inches, instes-d of four ; but as 

 -there must still be half an inch (f water lost, as be- 

 fore, it follows that one fourth part of the dead weigh: 



