214 AM MAI. MECIJANlSil. 



CHAPTER V. 



01 Till-: C11AXCKS IN THE PLANK OF THE DIIJD'S WING &'F 

 DIFFERENT POINTS IN ITS COURSE. 



New determination of tlie trajectory of llio wing Description of apparatus 



Tninsiiiivsinii of a movement by the traction of a thread Instni- 

 ment an-l ap aratus to suspend the bird Experiment on the flight of 

 a pigeon An ilysis of the curves Description of the apparatus 

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

 .luring flight Relation of these changes of plane with the other 

 movements of the wing. 



NEW DETERMINATION OF THE TRAJECTORY OF THE AVISO. 



THE simultaneous analysis of the changes in the plane of 

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

 presented great dilliculties, if we had not discovered a new 

 arrangement of the apparatus, which allowed us to examine, 

 at the same time, an, almost inliuite number of different 

 movements. 



This simplification of the incthod consists in the employ- 

 ment of threads to transmit the movement of any point 

 whatever to the experimental apparatus, which in its turn, 

 bends it by the ordinary means to the registering instrument. 



Dcsci-ijitiuii of apparatus. Let fig. 102 bo two lever-drums 

 connected together, similar to those already represented in 



iig. 21. 



The kver L belorys 1o the experimental apparatus, that on 

 \\hichthemovernent 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 

 tbe lever L. From the san.e 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. 



