43 8 Dtfckarge of Fluids [Book VII. 



an additional pipe, and the quantity which would flow 

 through an orifice made in a thin partition, in which 

 there was a contraction of the ftream, are to each other 

 nearly as the three numbers, fixteen, thirteen, ten^ and 

 thefe proportions are found lufficiently accurate for 

 common purpofes. 



Hence alfo it may be inferred, that additional pipes 

 counteract only in part the contraction of the ftream. 

 The mod fenfible of all contractions of this nature is 

 that which takes place when water flows from a large 

 refervoir through a fmall aperture made in a thin 

 fubftance. 



If the additional pipe, inftead of being vertical, or 

 placed in the bottom of the velTel or refervoir, is hori- 

 zontal, or placed in the fide, it will afford the fame 

 quantity of water, provided that it is of the fame 

 length, and that the exterior aperture is placed at the 

 fame diftance below the furface of the water in the 

 refervoir. 



If the additional pipe, inftead of being cylindrical, is 

 conical, having its largeft bafe attached to the fide of 

 the refervoir, it will produce a much greater quantity 

 of water. The moft advantageous form, indeed, for 

 procuring the greateft quantity of water in a given 

 time through a certain aperture, is that which the 

 ilream itfelf naturally afiumes in coining out of an 

 aperture in a thin fubftance ; that is, the form given 

 to the pipe mould be that of a truncated cone, the 

 diameter of the fmaller bafe of which mould be the 

 fame as that of the aperture through which the water 

 is to flow. 



It is neceflary alfo, that the area of the fmaller bafe 

 mould be to the area of the greater as ten to fixteen j 

 and the diftance between the two bafes mould be nearly 

 equal to half the diameter of the greater bafe. The 



remainder 



