MancJiester Memoirs, Vol. xliv. (1900), No. II. 9 



number of inch holes fitted with screw phigs, for the 

 purpose of var)-ing the as^f^regate area of the discharging 

 orifices. The gases were mixed in various proportions 

 and ignited by an electric spark. The amount of 

 reactive force generated by the explosion of the gases 

 dircctl}' into the atmosphere was not, however, con- 

 sidered satisfactor}-, and the experiments were soon 

 discontinued. 



24. The results of all these experiments on the dis- 

 charge of elastic fluids, made with a view to the possibilities 

 of aerial locomotion, were purely negative, and proved 

 decisively that the solution of the problem was not to be 

 found in that direction. 



25. Science, however, has profited by these enquiries, 

 since with the apparatus and appliances at command 

 I was enabled to undertake a series of experiments on the 

 velocit}' with which air rushes into a vacuum, and to investi- 

 gate some phenomena attending the discharge of atmos- 

 pheres of higher into those of lower densit}'.* These 

 experiments were described in two papers read before 

 the Society, and showed : (i) that air of the mean 

 atmospheric pressure of 15 lbs. per sq. in. rushes into a 

 vacuum at the rate of 6^"] feet per second, or approxi- 

 mately one-half the velocity due to the height of a 

 homogeneous atmosphere, — the velocit}' due to the whole 

 height having been previously assumed to be correct ; 

 (2) that the times of discharge from an orifice of equal 

 volumes of air after expansion are inversely as the 

 pressures ; and (3) as a corollary to the preceding, that 

 the velocity of discharge of an elastic fiuid through a 

 simple orifice, at a constant temperature, was the same for 

 all pressures ; (4) that the hydraulic co-efficient, '62, for 



•Manchester Memoirs, \'ol. x.\x., 1887. Phd. Mag., December, 1S85 ; 

 June, 1886. 



