AERONAUTICS. 



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the best results were obtained when the range of the wing 

 and the speed with which it was urged were so regulated as 

 to produce a perfect reciprocation. Thus, if the range of the 

 wing be great, the speed should also be high, otherwise the 

 air set in motion by the right stroke will not be utilized by 

 the left stroke, and vice versa. If, on the other hand, the 

 range of the wing be small, the speed should also be low, as 

 the short stroke will enable the wing to reciprocate as per- 

 fectly as when the stroke is longer and the speed quicker. 

 When the speed attained is high, the angles made by the 

 under surface of the wing with the horizon are diminished ; 

 when it is low, the angles are increased. From these re- 

 marks it will be evident that the artificial wave wing reci- 

 procates in the same way that the natural wing reciprocates ; 

 the reciprocation being most perfect when the wing is 

 vibrating in a given spot, and least perfect when it is travel- 

 ling at a high horizontal speed. 



The Artificial Wing propelled at various degrees of speed 

 during the Down and Up Strokes. — The tendency which the 

 artificial wave wing has to rise again when suddenly and 

 vigorously depressed, explains why the elevator muscles of 

 the wing should be so small when compared with the depressor 

 muscles — the latter being something like seven times larger 

 than the former. That the contraction of the elevator 

 muscles is necessary to the elevation of the wing, is abun- 

 dantly proved by their presence, and that there should be so 

 great a difference between the volume of the elevator and 

 depressor muscles is not to be wondered at, when we remem- 

 ber th-at the whole weight of the body is to be elevated by 

 the rapid descent of the wings — the descent of the wing 

 being entirely due to the vigorous contraction of the powerful 

 pectoral muscles. If, however, the wing was elevated with 

 as great a force as it was depressed, no advantage would be 

 gained, as the wing, during its ascent (it acts against 

 gravity) would experience a much greater resistance from 

 the air than it did during its descent. The wing is con- 

 sequently elevated more slowly than it is depressed ; the 

 elevator muscles exercising a controlling and restraining 

 influence. By slowing the wing during the up stroke, 



