260 



ANIMAL MECHANISM. 



soldered to this tube, and is able to move with it to any point 

 along the rod, thus allowing full liberty to the movements of 

 flight, while no change of plane can be effected without com- 

 municating a movement of torsion to the rod. 



After some experiments, it became necessary to make im- 

 provements in this apparatus. Thus, the lever I had a tendency 

 to get twisted on account of the displacement of the feathers 

 during flight; it was replaced (fig. 109) by a piece with three 



Fig. 109. — Actual arrangement of the apparatus intended to experiment 14 

 upon the movements of the wing, and its change of plane, 



movable levers, h b h, turning in the same plane round a 

 common centre, like the blades of a fan. Each of these little 

 branches terminated in a hook. After having attached the 

 sliding tube to the false wing of the bird, the extremity of 

 each of these three blades was tied to one of the long feathers 

 of the wing. This ligature, made with india-rubber, gave 

 excellent results. 



The lever I (fig. 109) was also defective on account of its 

 unequal action. In its stead was substituted a pulley of short 

 radius, placed on the rod prolonged behind the Cardan joint. 

 The thin cord r r, which was to transmit the torsions of the rod, 

 passed round the wheel of this pulley. In this manner the 

 rotation of the pulley, resulting from the torsion of the rod, 

 always faithfully transmitted this torsion to the exDerimental 

 lever. 



To put an end to this long description of the instrument 

 intended to transmit the signals of the elevation and depression 

 of the wing, let us only say that the piece situated at the base 

 of the lever t t intended to transmit the vertical and 



