326 THE BORDERLAND OF SCIENCE. 



against the balloon. We know what the effect would 

 be in this latter case ; the balloon would soon be made 

 a complete wreck : and nothing else could happen in 

 the former case. 



But it may be seriously questioned, whether buoy- 

 ancy is a desirable feature in any form of flying- 

 machine. We have seen that a degree of buoyancy 

 sufficient to secure actual floatation in the air is in- 

 compatible with aerial navigation. We may now go 

 further, and urge that even a less degree of buoyancy 

 would be a mischievous feature in a flying- machine. 

 M. Nadar, the balloonist, makes a significant, though 

 not strictly accurate observation on this point, in his 

 little book on flying. Passing through the streets of 

 Paris, during the sedileship of Haussmann, he heard a 

 workman call from the roof of a house to a fellow- 

 workman below, to throw a sponge up. < Now,' says 

 Nadar, ' what did the cunning workman, who was to 

 throw the sponge up, do ? The sponge was dry, and there- 

 fore light and buoyant. Was it in this condition that 

 he threw it up to his fellow ? No ; for it would not 

 have been possible to send it above the first floor. But 

 he first wets the sponge ; and so makes it heavy ; and 

 then, when it has been deprived of the lightness which 

 is fatal to flight, he throws it easily to his fellow on 

 the house-roof? ' M. Nadar infers, that the first es- 

 sential in a flying-machine is weight ! 



Now what is true in the above reasoning is that 

 buoyancy renders flight as distinguished from aerial 

 floating impossible, or at least difficult. It is not 



