200 ANIMAL MECHANISM. 



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

 along tin- rod, thus allowing full liberty to tlic movements of 

 (light, while no change of plane ran be effected without com- 

 municating a movement of torsion to the red. 



After some experiments, it became necessary to mala; im- 

 provements in this apparatus. Tin s, the lever I bad a tendency 

 to get twisted on account of the displacement of the feathers 

 during llight; it was replaced (Jig. 10'J) by u piece with three 



1 i>;. 10!'. Aotn.-il arniii^fniciit of tlic :i|i]vir;itus intciulcil to experiment, 

 tlic movemeilta of tliu will,', ;iinlits ch.uigu tif 



niov.ilJe levers, lib, turning in the same plane round a 

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

 braiu-hes terminated in a hook. After having attached the 

 sliding tube to the false winy of the Lird, the extremity of 

 ach of these three blades Avas tied to one of the long leathers 

 of the uing. This ligature, made with india-rubber, gavo 

 \ ellent results. 



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

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

 rudiiis, placid on the rod prolonged behind the Cardan joint. 

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

 ] a--i d 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 experimental 

 lever. 



To pnl an vnd to thi* long description of the instrument 



intend' d to Iran SIM it the signals of the elevation and depression 



of 1 lie \\ ing, let us mi ly ,xi v that I he ] /ii < e si t uatcd at 1 he base 



the I'M r / / i, inli nd( d to transmit the \ertical and 



