184 Scientific InteUigehce.^^Zoology. 



denomination of bloodvessels or nerves. These striae I saw 

 distinctly, but whether they are either vessels or nerves, I can- 

 not tell. The motions of the animals are rapid and vigorous ; 

 and they are particularly remarkable for a large longitudinal 

 muscle, extending nearly the whole length of the body, which 

 enables them to bend their body into various contortions, and to 

 alter its form in a very remarkable manner*." 



14. Flying of Mmi and Birds. — M. Navier read to the 

 Academy of Sciences of Paris, the report of a committee, to 

 whom was referred the memoir of M. Chabrier, wherein is 

 proposed a method of flying, and of directing one''s flight in 

 the air ! The apparatus consists of huge wings ; the cavities 

 of which are filled with hydrogen gas, and which the flying 

 man is to move with his arms. The report states the com- 

 mittee's opinion to be, not only that the apparatus proposed 

 by M. Chabrier is incapable of effecting the object in view, but 

 that every machine constructed upon the same principle must 

 be equally ineffectual. To demonstrate this, M. Navier en- 

 deavours to calculate the muscular exertions made by birds 

 in flying, in order to compare it with what man is capable 

 of. According to his calculations, a bird, to sustain itself in the 

 air merely, without ascending or descending, employs in a 

 second a quantity of action equal to that which Avould be neces- 

 sary to raise his own weight to a height of 26 feet S inches ; but if 

 this bird desired to move horizontally with great speed, at the 

 rate, for example, of 49 feet 2 inches in a second, which is 

 often the case with birds that migrate, in their annual journeys, 

 the quantity of action which it would have to expend in a 

 second, would be equal to that which would be required to raise 

 its own weight to the height of 1,280 feet, or thereabouts. 

 Thus, in this case, it would employ a force nearly fifty times 

 greater than it required merely to sustain itself in the air. It 

 is therefore evident, that, in order to support itself on wing, a 

 bird must be less sensible of fatigue than a man in supporting 

 himself on his legs, if we have respect to the quantity of fatigue 

 which the one and the other are capable of enduring. It is 



• "We have before us a more detailed account of Ehrenberg's discoveries, 

 sent from Hamburgh, but too late for insertion in the present number of the 

 JoumaL 



