lO Wilde, On Aerial Locoviotion. 



the dischart^c through an orifice in a thin plate, is not 

 applicable to the discharge of elastic fluids, the co-efficient 

 for the latter being -937 ; (5) that in the discharge of 

 atmospheres of higher into those of lower density, the latter 

 act as a vacuum when the reci]:)ient atmosphere is not 

 greater than one-half the density of the higher atmosphere, 

 in confirmation of the results previously obtained by 

 different methods. 



26. The phenomenal rate of discharge of atmospheres 

 of higher into those of lower density was also shown to be 

 directly correlated with the phenomena observed in the 

 experiments of Richard Roberts and of Peter Ewart, 

 members of this Society.* Lord Rayleigh in his lecture 

 on " Flight," recently delivered at the Royal Institution, 

 described a similar experiment with a light piece of brass 

 plate, evenly pivoted in and nearly filling up an aperture 

 through which air was issuing under pressure, that tended 

 to set itself square to the aperture so as to block it as 

 much as possible, but, if started, continued \.o rotate in 

 either direction, emitting a roaring sound. This experi- 

 ment finds a full elucidation in the rarefaction of the air 

 near the discharging orifice, as shown in the experiments 

 of Roberts and of Ewart referred to. 



27. Having satisfied myself that the problem of aerial 

 locomotion was not to be solved by the reactive force of 

 elastic fluids, either with or without the aid of electricity 

 and magnetism, I repeated and extended some of my earlier 

 experiments on the reactive force of aerial screws. The 

 experiments were made with vanes from one to four feet 

 in diameter, adjustable to any angle, and driven at 

 different velocities up to 2,000 revolutions per minute. The 

 results obtained were not sufficiently promising to induce 



* Mamhesier Memoirs, Ser. 2, \'ol. \'., p. 208. Phil. Mag., 1829. 



