Chap. 3.] Dtfcbarge of Fluids, &V. 429 



height equal to that of the furface of the fluid above the 

 aperture, in the fame manner as a falling body acquires 

 a velocity capable of making it afcer-d to the height 

 from which it defcended. 



It is evident, from the theory of falling bodies, that 

 if the velocity of the fluid in running through the 

 aperture was uniformly continued, the fluid would 

 move through a fpace double the height of the fluid 

 above the aperture, in the fame time thac a falling body 

 would employ in defcending from that height. 



The height being the fame, the velocity of the fluid 

 in running out of the orifice will always be tfce fame, 

 whatever the fpecies of the fluid may be, and whatever 

 its dennty. It is true, that when the fluid has more 

 denfiiy it prefles more forcibly, but then the mafs is 

 more considerable, and it is evident, that when the 

 moving powers are proportioned to the maffes which 

 they put in motion, the velocities are equal. 



The quantities of a fluid difcharged in the fame 

 fpace of time through different orifices, fuppofing the 

 vefiels equally full during the whole of the experiment, 

 are to each other as the products of the areas of the 

 apertures by the fquare roots of the heights. For in- 

 ftance, it has been proved by experiment, that a circu- 

 lar orifice of an inch diameter, made in a thin vcfTel 

 or partition, and under a furface of fluid four feet in 

 height, will furnifh, in one minute of time, five thou- 

 fand four hundred and thirty - fix cubic inches 

 French. 



Jf, therefore, it was an object to afcertain how 

 much a circular orifice of two inches diameter, under 

 nine feet of height from the furface of the water, would 

 furnifh in the fame time, the following proportion 

 muft be employed (it mull be obferved, that the ori- 

 fice of two inches is four times as great as an orifice 



of. 



