ANIMAL MECHANICS. 



295 



Hence, we have, for the centre of the ellipse (66) — 



2-L 2 O.14433 



The distance of the actual axis of the wing, ST, from 0 is 64, 

 while the distance of the calculated axis of maximum work 

 is 68.4. 



(c.) Wing of the Common Heron. — The wing of the Heron 

 is shown in Fig. 79, where AB is the origin, and A'B' the 



0 



Fig. 79. 



insertion of the pectoral muscle ; S is the socket of the win<y- 

 bone, and ST perpendicular to OX, the bisector of the angle 

 AOB, is the axis round which the bone A'B' rotates. The 

 angle A OB is 45°, and, when divided, into nine equal parts 



