196 OUTLINES OF NATURAL PHILOSOPHY. 



section is diminished in the ratio nearly of 5 to 7, 

 Therefore we must take - of the above result for 



f* 



the true value of q ; so that q = - a? */2 g d. As* 



5 . 1 



- is nearly -= , we may suppose q - a? 



d. As *Jg d is the velocity acquired by falling through 

 - , it has been supposed by some writers, that the 



water issues only with the velocity that would be 

 acquired by falling through half the depth of the 

 fluid- CAVALLO falls into this mistake, vol. n. 

 chap. 7. p. 16& 



286. Water issuing through an oblique pipe in 

 the side of a vessel which is kept full, describes a 

 parabola in a vertical plane, passing through the 

 axis of the pipe ; and the directrix of the parabola 

 is the line of common section of the said vertical 

 plane with the surface of the water produced. 



That the curve is a parabola, follows from the theory 

 of Projectiles, 93. ; and that the directrix is the 

 same, whatever be the angle of elevation, follows 

 from this, that the water issues with the same veloci- 

 ty whatever direction the axis of the pipe has, viz. 

 that which corresponds to the height of the surface 

 of the fluid above the orifice, 94. a. 



3 287. Tbe 



