ON AEKIAL LOCOMOTION. 



319 



fectly with this iii)peiulaf;c cut short off; it probably performs an im- 

 portant fiiuctiou ill rapid steering, for it is to be remarked that most 

 birds that have either to pursue or evade pursuit are amply provided 

 with this organ. 



The foregoing reasoning js based upon facts, which tend to show that 

 the flight of the largest and heaviest of all birds is really performed 

 with but a small amount of force, and that man is endowed with suffi- 

 cient muscular power to enable him also to take individual and extended 

 tlights, and that success is probably only involved in a question of suit- 

 able mechanical adaptations. J5ut if the wings are to be modelled in 

 imitation of natural examples, but very little consideration will serve 

 to demonstrate its utter impracticability when applied in these forms. 

 The following diagram, Fig. 1, would be about the proportions needed for 



Fig. I. 



a man of medium weight. The wings a a must extend out 00 feet from 

 end to eiul and measure 4 feet across the broadest part. The man, h, 

 should be in a horizontal position, incased in a strong frame-work, to 

 which the wings are hinged at c c. The wings must be stiffened by 

 elastic ribs extending back from the pinious. These must be trussed 

 by a thin band of steel, e e, Fig. 2, for the purpose of diminishing the 



P'ig:.2. 



weight and thickness of the spar. At the front, where the pinions are 

 hinged, there are two levers attached and drawn together by a spiral 

 spring, r7. Fig. 2, the tension of which is sufiftcient to balance the weight 

 of the body and machine and cause the wings to be easilj' vibrated by 

 the movement of the feet acting on the treadles. This spring serves 

 the purpose of the pectoral muscles in birds. But with all such arrange- 

 ments the apparatus must fail ; lenrjth of icing is indispensable! and a 

 si)ar 30 feet lotig must be strong, heavy, and cumbrous; to propel this 

 along through the air at a high speed would require more power than 

 any man couhl command. 



In repudiating all imitations of natural wings, it does not follow that 

 the only channel is closed in which Hying mechanism may prove suc.- 

 cessful. Though birds do Uy u[)oii definite mechanical principles and 

 with a moderate exertion of force, yet the wing must necessarily be a 

 vital organ and member of the living body. It must have a marvellous 

 self-acting i)rinciple of repair in cnise the feathers are broken or torn; 

 it must also fold up in a small compass and form a covering for the 

 bodv. 



