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AERONAUTICS. 



1st, The Balloonists, or those who advocate the employ- 

 ment of a machine specifically lighter than the air. 



2dy Those who believe that weight is necessary to flight. 

 The second school may be subdivided into 



(a) Those who advocate the employment of rigid inclined 



planes driven forward in a straight line, or revolving 

 planes (aerial screws) ; and 



(b) Such as * trust for elevation and propulsion to the 



vertical flapping of wings. 



Balloon, — The balloon, as my readers are aware, is con- 

 structed on the obvious principle that a machine lighter than . 

 the air must necessarily rise through it. The Montgolfier 

 brothers invented such a machine in 1782. Their balloon 

 consisted of a paper globe or cylinder, the motor power being 

 super-heated air supplied by the burning of vine twigs under 

 it. The Montgolfier or fire balloon, as it was called, was 

 superseded by the hydrogen gas balloon of MM. Charles 

 and Eobert, this being in turn supplanted by the ordinary gas 

 balloon of Mr. Green. Since the introduction of coal gas in 

 the place of hydrogen gas, no radical improvement has been 

 effected, all attempts at guiding the balloon having signally 

 failed. This arises from the vast extent of surface which it 

 necessarily presents, rendering it a fair conquest to every 

 breeze that blows ; and because the power which animates it 

 is a mere lifting power which, in the absence of wind, must 

 act in a vertical line. The balloon consequently rises through 

 the air in opposition to the law of gravity, very much as a 

 dead bird falls in a downward direction in accordance with 

 it. Having no hold upon the air, this cannot be employed as 

 a fulcrum for regulating its movements, and hence the car- 

 dinal difficulty of ballooning as an art. 



Finding that no marked improvement has been made in 

 the balloon since its introduction in 1782, the more advanced 

 thinkers have within the last quarter of a century turned 

 their attention in an opposite direction, and have come to 

 regard flying creatures, all of which are much heavier than 

 the air, as the true models for flying machines. An old 

 doctrine is more readily assailed than uprooted, and accord- 

 ingly we find the followers of the new faith met by the 

 assertion that insects and birds have large air cavities in 



