SUMMARY OF HYDRAULICS. - *JQ 



the moft hidden operations of nature, and will confider the 

 name of Volta as worthy to be cl ailed with thole of Lavoilier, 

 Prieftley, Cavenclifli, and the other illullrious founders of the 

 pneumatic chemiftry. 



III. 



A Summary of the ?noJl afeful Parts of Hydraulics, chiefly ex- 

 tracted and abridged from Eytekvem's Handbuch der Mechanik 

 und der Hydrautik, Berlin, 1801. By Thomas Young, 

 M. D. F. R. S. 



(Concluded from Page 35.) 



vL/HAPTER 9. Of the motion of water in pipes. Motion of water 



The author has attempted to Amplify this fubject nearly in in pipeS * 

 the fame manner as that of the motion of rivers, and appa- 

 rently with confiderable fuccefs. He obferves, that the head 

 of water may be divided into two parts, one of which is em- 

 ployed in producing velocity, the other in overcoming the 

 friction : that the height employed in overcoming the friction 

 mull be as the length of the pipe direclly; and alfo directly as 

 the circumference of the feclion, or as the diameter of the pipe, 

 and inverfely as the content of the feclion, or as the fquare of 

 the diameter ; that is, on the whole, inverfely as the diameter ; 

 this height too mult vary, like the friction, as the fquare of the 

 velocity. 



Hence / =iL.z>%/ denoting the height due to the friction, To find the vc- 

 d locity j 



and a a conftant quantity : therefore, v z =: , L — Now the 



al 



height employed on the friction, correfponds to the difference 

 between the actual velocity and the actual height, or/=/j — — 



where b is the coefficient for determining the velocity from the 



, ■ , t r *••••« b z dh—dv* , - b % dh 



height; confequently, £*= , and v 



ab*l ab^l+tf 



Now b=:6.6, and from Buat's experiments, ab % is determined 

 to be .021 1, which agrees the moft accurately where the velo- 

 city is between <5 and 34 inches in a fecond. Whence we have 



