6 Wilde, On Aerial Locomotioii. 



work on terrestrial magnetism, and denounced the idea of 

 the diurnal rotation of the earth as extravagant, declaring 

 that it could be demonstrated to be n^iost false. 



14. I\Ty own investigations on the possibilit}' of aerial 

 locomotion were commenced as early as the year i860, 

 when strongly imbued with the kinetic theory of gases, I 

 sought, by various means, to disturb the equilibrium of 

 pressure in a metal cylinder cotitaining air by the rapid 

 heating and cooling of its opposite ends simultaneously. 

 The cylinder was suspended from a balance during the 

 operation of heating and cooling, but no difference of 

 pressure between the two ends was manifested. 



15. The next attempt to produce a change of equili- 

 brium in a vessel was by the reaction caused by the 

 discharge of steam of high pressure from a number of 

 orifices of various sizes and forms. Good results were 

 anticipated from this investigation, as Mr. W. Froude, 

 F.R.S., in a paper read before the Institution of Civil 

 Engineers (1847),* "On the discharge of elastic fluids 

 under different pressures," had challenged the correctness 

 of the commonly accepted formula for the velocity of 

 discharge. This distinguished engineer stated that the 

 correction required by the formula for non-elastic fluids 

 when applied to those which are elastic, was to divide its 

 results b\- the square root of its corresponding expansion ; 

 thus "a fluid which in issuing expands to four times its 

 volume will be discharged at only half the rate assigned 

 to it by the ordinary theory, and if expanding lOO times, 

 only at one-tenth of that rate." Hence, from this formula, 

 by increasing the pressure indefinitely, a point would be 

 arrived at when the discharge would be indefinite!)' small 

 or cease absolutely. Now had the proposed formula been 



• Proc. Inst. Civil Engineers, Vol. 6, 1847. 



