ON AERIAL NAVIGATION. ] g^ 



part, when the machine is in the act of skimming; and 

 likewise the advantages of the low hinge, with the principle 

 of leaving little or no interval without support. 



All that has hitherto appeared respecting Mr. Degen'sap- Mr D gen's 

 paratus is, that it co>nsisted of two surfaces, which were apparatus. 

 worked by a person sitting between them. This statemeat 

 communicates no real information upon the subject; for 

 scarcely any one would attempt to fly without two wings; 

 without these being equally poised by placing the weight 

 between them; and also, without these surfaces being capa- 

 ble of receiving motion from his muscular action. 1 may be 

 altogetlier mistaken in my conjecture; ray only reason for as-, 

 cribing this structure of mine to Mr. Degen's machine is, 

 that, if it were properly executed upon this principle, it would 

 be attended with success. The drawing, or rather diagram, 

 which is given of this machine in the first part of my essay, 

 is only for the purpose of exhibiting the principle in a form 

 capable of being understood. The necessary bracings, &c., 

 required in the actual execution of such a plan, would have 

 obscured the simple nature of its action ; and were therefore 

 omitted. The plan of its movement is also simply to exhi- 

 bit, in a tangible form, the possibility of effecting the intend- 

 ed alternate motion of the parachutes. The seat is fronted 

 lengthwise for the purpose of accommodating the mode of 

 communicating the movement. 



A fifth mode of avoiding leverage is by using the continu- 

 j . „ , ,. , • , r, r • First method, 



ed action or oblique horizontal nyers, or an alternate action 



ofthesame kind, with surfaces so constructed as to accommo- 

 date their position to such alternate motion; the hinge or 

 joint being in these cases vertical. In the construction of 

 large vessels for aerial navigation, a considerable portion of 

 fixed sail will probably be used ; and no more surface will be 

 allotted, towards gaining the propelling power, than what is 

 barely necessary, with the extreme temporary exertion of the 

 first mover, to elevate the machine and commence the flight. 

 In this case the leverage of the fixed surface is done away. 



The general difficulties of structure in aerial vehicles, Qgne,.,] jjifi. 

 (arising from the extension, lightness, and strength required culties. 

 in them ; together with great firmness in the working parts, 

 «ad at the same time such an arrangement as exposes no un- 



nrcessary 



