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of ~ of an inch diameter in 1 5 feconds ; by the foregoing formula 

 the height from which a body mufi fail to acquire tiie velocity 

 with which the water is difcharged will be 8,35 inches ; that, is a 

 fpace which is to the whole height of the water above the orifice as 

 10 to 24 nearly. But as it is a difficult matter to keep the fluid 

 always at the fame height, without encreafing the prefTure by pour- 

 ing it in, it may perhaps be confidered a more cxad method to cal- 

 culate a priori the time in which the vefTel ought to difcharge 

 itfelf, and noting the adlual time of the difcharge by experiment, 

 to diminifh the velocity of the efHux determined according to 

 theory in the fame ratio in which the time of the difcharge has 

 been encreafed. 



Now as the bafe of the vefTel is to the orifice, fo is the time 

 in which the vefTel would empty itfelf to that in which a body 

 would fall freely through the height of the water in the vefTel : 

 let therefore B denote the bafe of a cylindrical or prifmatic 

 vefTel, in which is an orifice whofe area is O ; the time in which 

 a body falls through A, the altitude of the fluid, is equal to 



^ y in feconds j therefore 7=: X v^ y is the time required in fe- 

 conds. 



Let a the altitude of a vefTel filled with mercury be 9 inches, 

 / 193 inches, the diameter of the cylindrical vefTel i inch, and 

 the diameter of the circular aperture ^ of an inch. The time of 

 the difcharge by theory, according to the foregoing formula, will 

 be 86,4 feconds 5 but by experiment it is found to be 140 feconds 

 nearly ; therefore the velocity of the efflux by theory is to be 



diminiflied 



