gQ SUMMARY OF HYDRAULICS. 



v*=J*' edh , or £=45.5 /-lY but it is fome- 



what more accurate to make e=50 */f — J> a ^ the 



V \l+50dj 9 



meafures being exprefled in Englifti feet. 



allowance for When the pipe is bent into angles, or rather arcs, we mult 



diminifli the velocity thus found, by taking the product of its 

 fquare multiplied by the fum of the fines of the feveral angles 

 of inflection, and then by .0038 ; which will give the degree 

 of preflure employed in overcoming the refi fiance occafioned 

 by the angles: and deducting this height from the height cor- 

 refponding to the velocity, we may thence find the corrected 

 velocity. 



Compound pipes. Mr. Eytelwein proceeds to investigate, both theoretically 

 and experimentally, the difcharge of water by compound pipes, 

 with apertures of various dimenfions between them : he allows 

 at each orifice for the contraction of the ftream, and calculates 

 the height neceflfary to produce the increafe of velocity in each 

 inftance, allowing alfo for the friction of the pipe. But the 

 velocity thus found is fomewhat fmaller than the refult of his 

 experiments ; probably becaufe the whole of the force of the 

 water accelerated at any orifice, is not immediately loft as foon 

 as it arrives at a wider part of the pipe. The afcent of water 

 in a compound pipe, to the level of a refervoir, is next confi- 

 dered, a cafe which often occurs in pump- work ; and an ap- 

 proximation to the velocity of afcent is deduced from theory 

 and compared with experiment. 



Jets of water. Chapter 10. Of jets of water. 



This chapter contains little that is new or interesting ; it is 

 well known, that the velocity of a jet is greateft when it fprings 

 through an orifice in a thin plate, and in this cafe, the height 

 falls little thort of that of the refervoir. 



Impulfe or hy- Chapter 1 1. Of the impulfe or hydraulic prefTure of water. 



drauhc preflure There are three principal cafes of the impulfe of water falling 

 perpendicularly on plane furfaces: when a detached jet of 

 water ftrikes the plane; when the plane moves in an unlimit- 

 ed extent of water, or is very fmall in refpecl to a ftream that 

 ftrikes it; and when the impulfe takes place in a limited 

 channel. 



When the ftrerni Suppofing a ftream of water to ftrike againft a plane fo as to 



¥" a11 its vdo " lofe all its motion, it is obvious, that the force that deftroys 



«*> the 





