12 W'lLDK, On Aerial Locomotion. 



30. These conditions or criteria may be summarised 

 as follows : — 



(i.; An aviatini,^ machine should have power to rise 

 from any point of the earth under ordinary 

 conditions of wind and weather ; 

 (ii.) The aviators should be able to descend with the 



machine at any time and at any place ; 

 (iii.) The machine should have power to move in any 

 direction, vertically, horizontall\', or to remain 

 stationary at any height, within practicable 

 limits, above the earth. 

 (iv.) The machine should contain within itself an 

 automatic principle of safety by which, in the 

 event of any accident to a vital part of the 

 mechanism, the descent would be made with- 

 out danger to the aviators, or damage to 

 objects upon which the machine might happen 

 , to alight. 



31. It is now all but universally admitted that j/ian, 

 by his own strength alone, can never attain the power of 

 flight by the aid of any mechanical appliance through zvhich 

 his muscular force is or may be transmitted. 



32. Although the balloon is a most brilliant invention 

 from the great impulse which it has given to the study 

 of aeronautics, from the service it has rendered to meteoro- 

 logical science, and from its application to the conduct of 

 military operations, yet, as a means of locomotion, it fails 

 to comply with three out of the four criteria specified 

 above. The numerous attempts that have been made to 

 give direction to the course of a balloon have only 

 succeeded in a comparatively still atmosphere, and clearly 

 demonstrate the physical impossibility of overcoming this 

 difficult)- even in a moderate current of air. The power 



