268 



ANIMAL MECHANICS. 



This work will be a maximum, when $ = o, when it becomes 

 f n 7/1 : . ' a(a + b) 



Therefore, when a the distance OS (Fig. 69), of the socket 

 joint from the vertex of the triangle is given, the maximum 

 effect will be produced when the socket lies on the bisector 

 of the vertical angle of the triangular muscle, that is, on a line 

 perpendicular to the locus of socket for maximum effect, for 

 axis perpendicular to the plane of the muscle considered in 

 Prop. B. Hence, we see that the conditions for maximum 

 effect are essentially different for the two axes of rotation, and 

 that it is not possible for a given muscle to produce the maxi- 

 mum effect, by its rotation of the bone AB round both axes 





Y S 





0 





Y f / 



y^X^^t' I 





\b/ 





/ s 





Y 



Fig. 71. 



This is a remarkable result, and will lead us to important con- 

 sequences. 



