PASSAGE OF AIR THROUGH PIPES AND APERTURES. 103 



inches in diameter, was cut in the chest, and in this could 

 be placed; or to it affixed, thin plates with holes, or other 

 means for the egress of air. 



The method of esperimenting was to note the time in 

 seconds and tenths occupied by the running down of the 

 bellows. The capacity of the bellows being known to be 

 29,660 cubical inches, this observation gave the quantity 

 of air issuing per second, plus the unavoidable leakage of 

 the bellows. The amount of the latter was ascertained 

 by observing the time in which the bellows ran down 

 when the hole was made tight, and being subtracted from 

 the gross effect, gave the quantity which actually passed 

 through the orifice. 



Theoretically the quantity of air emitted in a given 

 time ought to be proportional to the size of the aperture 

 in the thin plate, multiplied by the square root of the 

 pressure, or, in other words, the quantity emitted per 

 square inch of aperture divided by the square root of the 

 pressure ought to be a constant quantity. My observa- 

 tions to confirm this law were made with circular holes in 

 thin tinned iron, measuring 0*^35, I'o^g, and i"6i inch in 

 diameter respectively. The pressure and temperature of 

 the air in all the experiments were about 29*8 in. and 4° cent. 



Diameter of 

 aperture. 



Pressure, in inches 

 of water. 



Cubic inches of Air 



discharged per second, 



reduced to one square 



inch aperture. 



Cubic inches of Air 



discharged per second, 



divide.} by square root 



of pressure. 



o'535 j 



1-44 



496 



413-3 



5-6 



1033-3 



436-8 



I '045 j 



1-44 

 5-6 



541 '4 

 1058-4 



451-2 

 447-5 



r6i \ 



I "44 



589-5 



491-2 



I 



5-6 



1132-7 



478-7 



The last column of the above table shows the accuracy 

 of the law so far as pressure is concerned, but seems to 

 indicate a slight increase of the quantity issuing per square 

 inch as the aperture becomes larger. 



