ANIMAL MECHANIlSM. 



CHAPTER V. 



OF THE CHANGES IN THE PLANE OF THE BIED'S WING .AT 

 DIFFERENT POINTS IN ITS COURSE. 



New determination of the trajectory of the wing— Description of apparatus 

 — Transmission of a movement by the traction of a thread Instru- 

 ment and ap[)aratus to suspend the bird — Experiment on the flight of 

 a pigeon— Analysis of the curves— Description of the apparatus 

 intended to give indications of the changes in the plane of the wing 

 during flight — Relation of these changes of plane with the other 

 movements of the wing. 



NEW DETEKMINATION OF THE TRAJECTORY OF THE WING. 



The simultaneous analysis of the changes in the plane of 

 the wing, and of the various phases of its course, would have 

 presented great difficulties, if we had not discovered a new 

 arrangement of the apparatus, which allowed us to examine, 

 at the same time, an almost infinite number of different 

 movements. 



This simplification of the method consists in the employ- 

 ment of threads to transmit the movement of any point 

 whatever to the experimental apparatus, which in its turn, 

 sends it by the ordinary means to the registering instrument. 



Desa iption of apparatus. — Let fig. 102 be two lever-drums 

 connected together, similar to those already represented in 

 fig. 21. 



The lever L belongs to the experimental apparatus, that on 

 which the movement to be studied is to act. On the frame 

 of this first instrument let us place an arm of bent wire, from 

 the extremity of which an india-rubber thread, F, will pass to 

 the lever L. From the same lever hangs a cord of twisted 

 silk, C C, to which is suspended a leaden ball. 



Let us suppose the ball to be at its lowest position — at 

 the point A — the lever L occupies the place marked by a dotted 

 line, while in the registering instrument the air driven out 

 raises the lever L', which traces the movement. 



