Mr. MacBL/on on the Compression of Water. 263 



and resolving the pressures into columns of the respective substances, 

 we have the proportionate discharges due to these columns: — 



Water, Gas, 



as -v/ 11.736 feet : 2 : 2152 :: -/ 122 ; 6941 



cubic feet, which may be reckoned to be identical with the result 

 brought out by experiment. 



The Abbe Bossuet found by experiment, conducted with great care, 

 that a pipe, 2 inches in diameter, 150 feet long, with the pressure of 

 a column of water 2 feet in height, discharged 5*232 cubic inches, or 

 3*0278 cubic feet of water per minute. 



I have been favoured by the results of two experiments made with 

 pipes of 2 inches in diameter, and 150 feet long, which, with a pres- 

 sure of one vertical inch of water, discharged 22*66 cubic feet of gas, 

 sp. gr. 560, and with 2 inches of water 35.16 cubic feet. 



In contrasting these experiments, it is to be remarked that the pipes 

 are of the same diameter, and of the same length, consequently, the 

 only correction necessary is that due to the variation in the height of 

 their respective impelling columns — thus, as before, the experiment 

 with one inch of water — 



Water, cubic feet. Gas, 



as -/ 2 feet, 30278, so is a/ 122 feet, 23*647, 



the actual discharge with one inch being 22*66 ; and that of 2 inches 

 of water — 



Water, Gas, 



as V 2 : 30278, so is ^ 244 feet to 33*443 



cubic feet — the actual discharge as above having been 35*16. 



In 1819 M. Gerard made various experiments with gas apparatus con- 

 structed for lighting the Hospital of St. Louis, at Paris, to ascertain 

 the discharges of gas and air through pipes at the distances of 402^, 

 1233, and 2043 feet respectively from the gasometer, — the discharges 

 of AIR with a pressure of 0*858 of an inch of water were 30*205, 18150 

 and 13*237 cubic feet per minute. 



Not having any direct experiments with water made under precisely 

 the same conditions, I shall only apply the hydraulic formula of Dubuat, 

 to show the similarity of discharges of that fluid xmder the same cir- 

 cumstances. 



0*858 of an inch of water is equal to 58,334 feet of air — with this 

 head the discharge of water by the same pipe, about the distances 

 above stated, would be 36-206— 21,598, and 14015 cubic feet • 



The close approximation of all these results wiU, I hope, be a suffi- 

 cient warrant to me for having brought the subject under notice of the 

 Society, with a view to provoke further inquiry ; whether the calcu- 

 lations I have entered on, or the deductions drawn from them, be correct 

 or not 



