FLYING-MACHINES, ETC. 455 



estimations previously given by Navier, This experiment demon- 

 strated that the muscular strength of birds, although notably greater, 

 for equal weights, than that of mammals, did not exceed a reasonable 

 estimation. 



Our helicoptei'ons and areoplanes which performed with success 

 on the 2d of July, 1875, before the Physical Society, have a numerous 

 oflspring. They have been imitated with various success by Croce- 

 Spinelli and MM. Montfallet, Petard, and Tantin. 



The action of these machines, in fully confirming our ideas and 

 calculations on the resistance of the atmosphere, encouraged us to 

 attempt the construction of a mechanical bird with flapping wings. 

 The diversity of the hypotheses as to the nature of fliglit, proposed in 

 France and in England, though bearing witness to the difficulties to 

 be met wnth in the construction of this mechanism, yet rendered the 

 problem peculiarly interesting. . '^ 



The experiments heretofore made with mechanical birds had been 

 very discouraging. M. Artingstall and M. Marey had alone obtained 

 effective results. M. Artingstall states that, some thirty years since, 

 he had an artificial bird Avhich flew at the end of a tube jointed on to 

 a steam-boiler. M. Marey, whose beautiful physiological experiments 

 are so well known, constructed, in I8V0, artificial insects which, at- 

 tached to a radial tube carrying a counterpoise equal to two-thirds of 

 their weight, rose and flew in a circle by the aid of their wings. The 

 compressed air which set the wnngs in motion was conveyed to them 

 through the radial tube from a compression-pump worked by hand.* 

 It remained to gain the two-thirds of the weight of the insect and to 

 cause the latter to carry with it its motor instead of having the wings 

 moved by a force conveyed to the insect from without. 



Encompassed by the divers hypotheses of the action of the wing 

 given by Borelli, Huber, Dutrochet, Strauss-Durckeim, Liais, Petti- 

 grew, Marey, d'Esterno, De Lucy, Artingstall, etc., and in view of the 

 very complicated motions they had assigned to that organ and to each 

 of its quills motions which are, for the most part, inimitable in a me- 

 chanical bird W'C decided to reason out for ourselves, by relying on 

 the laws of the resistance of the air and on some of the most simple 

 facts of observation, what are the motions of the wing really necessary 

 to flight. We found 1. A double oscillation, a depression, and an 

 elevation of the wings transverse to the path of flight. 2. The change 

 of the plane of the same during this double motion ; the lower surface 

 of the wing facing below^ and behind during its depression, so as to 

 sustain the bird, the same surface of the wing facing below and in 

 front during its elevation, so that the wing is raised with the least re- 

 sistance by cutting the air with its edge w^hile the bird flies. These 

 movements, moreover, were admitted to be correct by a large num- 



1 See Fig. 87, on page 202 of Marey's " Animal Mechanism," published in the " Inter- 

 national Scientific Series." 



