190 UK I FORM PIPE CONNECTING TWO RESERVOIRS. 



with the whole fall in the cases which most commonly 

 occur. 



COB. 2. For very long pipes, 1 +/3 is so small compared. 



ith f-j, that i 

 d 



and (4) become 



with f-j, that it may be neglected altogether, and (2), (3), 



< 5 > 



Using the value of/ 1 , as determined by Poncelet, viz.,/ = 

 .023, with the value of (3 = .5, we have, from (3), 



Eytelwein gave a formula which nearly coincides with 

 this. (See Storrow on Water Works, p. 56.) 



When the pipe is very long, d is very small compared 

 with I, and (8) becomes 



(9) 



REM. It is immaterial as regards the velocity, and the quantity 

 discharged, whether the pipe is horizontal or inclined upwards or 

 downwards, so long as the length of the pipe and the total head, or 

 depth of the end of discharge below the level of the surface of the 

 water in the reservoir, remain unchanged. If the inclined pipe is 

 longer than the horizontal, of course its surface will present more fric 

 tion against the motion of the water than the horizontal one, aud thus 

 diminish the velocity of discharge ; but if the inclined pipe be the 

 same length as the horizontal, and have the same head, then each of 

 them will discharge the same quantity in the same time. 



It is evidently necessary, in every case, that the entrance to the 



