Chap. 3.] through Jmall Apertures. 435 



than the great ones, under the fame height of water in 

 the refervoir ; becaufc, comparatively to the extent of 

 the area of each orifice, there are more points of friction 

 againft the fides of the orifice in the fmali than there 

 are in the great ones ; for the circumferences do not 

 diminifh fo much as the areas. 



5. That of many apertures of equal areas, that of 

 which the circumference is the leaft will, on account 

 of the friction, furnilh more water than the others, 

 under the fame height of the refervoir ; circular aper- 

 tures are, for this reafon, the moft advantageous of alii 

 for the circumference of a circle is the morteft line 

 that can be made ufe of to inclofe a given fpace ; there- 

 fore there is lefs furface of friction relatively to the fize 

 of the area. 



It is eafy to perceive, that the quantity of water 

 difcharged in the table of experiments is not near 

 fo great as might be expected from the extent of the 

 areas and the heights of the refervoirs. The quantity 

 is in fait diminifhed by the friftion, and ftill more by 

 the contraction of the ftream ; for the velocity which 

 is in proportion to the entire altitude of the fluid is not 

 f?nfibly changed. Suppofing, firft, that the area of 

 the ftrcam is the fame as that of the orifice ; and liip- 

 pofing, fecondly, that the ftream is contracted, then 

 the difference of the quantities afforded is as fixteen to 

 ten ; that is, fuppofing the area of the aperture to be 

 diminifhed in the proportion of fixteen to ten, the 

 difcharge of the fluid out of veffels kept equally full 

 may be determined with fufficient exactnefs. By the 

 expreffion, an inch of water, is underftood the quantity 

 which flows out of a circular and lateral orifice of one 

 inch diameter, the furface of the water being con- 

 ftantly kept feven-twelfths of an inch above the cen- 

 ter of the orifice. This is the cafe with the eleventh 

 F f 2 experiment 



