250 COEFFICIENT OF EFFLUX. 



Circular, sharp-edged orifices, .... 0.563 to 0.788 



Short, cylindrical mouth-pieces, ... 0.75 

 Conical pipes, whose angle of convergence 



is about 6, 0.92 



Conical converging mouth-pieces, well 



rounded off, 0.98 



132. The Quantity Discharged. Let k be the area 

 of the orifice in square feet, and Q z the discharge per sec- 

 ond in cubic feet at the pressure of the external air. Then 

 we have, from (1) of Art. 129, 



p* 



+ at) log (1) 



[from (7) of Art. 129] ; 

 or, from (8) and (9) of Art. 129, we have 



= 1299/ 



(1 + * 



When Q z is reduced to the pressure of the air inside the 

 vessel, we have, from Art. 48, 



QiPi = QiP*'> 



.-. Q, = 1299,^^^(1 + at) log (*_+*). (4) 

 From (4) of Art. 130, we have 



a + o| 



Q = impk I - (5) 



_/M 2 



\aj 



