HYDRAULICS. 195 



Therefore, let d be the depth of the fluid ; g the 

 velocity acquired by a falling body in one se- 

 cond ; v the velocity with which the water issues ; 



v = 



If the velocity with which the fluid issues from the 

 orifice, were turned directly upward, it would carry 

 it to the level of the surface of the fluid. 



285. The quantity of water that issues in one se- 

 cond, through a given orifice, is equal to a column 

 of water having the area of the orifice for its base, 

 and the velocity with which the fluid issues for its 

 altitude. 



a. Hence, if a 2 be the area of the orifice, d the 

 depth of the water above the orifice, and q the 

 quantity of fluid running out in one second, 



q = a 1 



b. Of the quantities g, a and c/, any two being gi- 

 ven, the third may be found : 



/v2 Q j Q- 



ii . =r -- t , d rr - . 



JZgd 2 4 



The quantity of water that issues through an orifice, 

 is as the area of the orifice multiplied into the 

 square-root of the depth. 



c. When the experiment is made, it is found that 2 

 must not be taken equal to the exact area of the 

 orifice. The vein of water that issues through the 

 small orifice, suffers a contraction, by which its 



N 2 section 



