On Aerial Navigation. 199 



an angle of 45" to the horizon, by means of the weight suspended 

 in the car. But ahttle calculation will show that the lateral mo- 

 tion produced is very small, and not sufficient to counteract any 

 considerable wind ; for the whole vertical velocity in the ascent 

 is easily computed, and is not large; and the resolved motion in 

 a lateral direction, being a function of the angle of inclination, 

 is still smaller, and much less than the velocity of any gale of 

 wind. 



3. A great number of mechanical contrivances in imitation 

 of wings and oars have been suggested, and even tried, but with 

 a most discouraging degree of success. Upon examining the 

 cause of these failures, it is easy to see that the experiments have 

 been made on principles fundamentally erroneous. In the first 

 place, the power has always been applied to the car, though it is 

 obvious that in such a case the greatest part of the power is 

 lost in giving the car a rotatory motion round the balloon, and 

 that the power, in order to be" entirely effective, should be ap- 

 plied in a line passing through the centre of pressure of the 

 whole system. In the second place, the mechanism imitated 

 has been that employed by Nature in enabling a bird to fly, 

 though it is obvious that the animal's wings are contrived as 

 much for support in the air, as for lateral motion. Our whole 

 attention should be directed to the mechanism of fishes, whose 

 air-bladders assimilate them to an inflated balloon, and in v/hich 

 the system is wholly contrived for the purposes of horizontal mo- 

 tion, progression being produced by the rapid vil)rations of th'; 

 tail, acting like a single oar upon the hinder part of a boat. 

 When we see the rapid progress made by the salmon against the 

 swiftest stream, we should not despair oi' success; and certainly 

 not on account of the small muscular power of man, if we con- 

 sider that the steam-engine with the weight of one man com- 

 mands the power of four. It is indeed a matter of serious in- 

 (juiry, whether such a machine would not require something 

 more solid to work upon than a metallic poop, or any thing 

 which the balloon could support. It is obvious that much ad- 

 vantage will be gained, if any meclianism acting on the air should 

 move with much greater velocity than the balloon, as the re- 

 sistance or power increases with the scjuare of the velocity. It 

 will also be a matter of experiment what form of balloon is least 

 resisted ; for the received systems on this subject are universally 

 allowed to be erroneous, as the resistance varies as ar- + br [b 

 being negative in an clastic medium), and as it will probably be 

 found to be a function of the figure of the body resisted. 



N 4 L. Queries 



