358 



ANIMAL MECHANICS. 



On marking off the points 0 and 0' on the pelvis and 

 femur, I found — 



Distance of 0 from centre of socket - 2.63 in. 



Distance of 0' from centre of socket = 2.58 ,, 



Difference, . . 0.05 in. 



The preceding facts demonstrate in a remarkable manner 

 the truth of the Postulate, p. 238, as applied to the case of 

 skew muscles. The postulate requires the distances of the 

 points 0 and 0 / from any point situated on the common in- 

 tersection of the two planes containing the bones AB and 

 A'B' to be equal; and, from the conditions of the joint, the 

 centre of the socket is supposed to lie on that intersection. 

 Bringing together all the results, we find 



Broof of the Postulate for Shew Muscles. 



Muscle. 



Distance 

 from 0 to 

 Socket. 



Distance 

 from 0' to 

 Socket. 



Difference. 



Angle. 



Adductor secundus (/3). 











1. Llama, 



2.88 in. 



3. 14m. 



0.26 m. 



470 2 8' 



2. " Master Magrath," . 



i-95 „ 



2.28 „ 



0.23 „ 



49 28 



3. Woman, .... 



3.84 „ 



3- 6 4 » 



0. 20 



43 29 



4. Leopard, .... 



1.82 „ 





0. 50 ,, 



5i 53 



Adductor secundus (a), 











5. Leopard, .... 



2. 63 



2.58 H 



0.05 „ 



44 27 



m 







Mean, . 



47° 21' 



The last column of this Table shows the angle made by 

 the fibre 00' with the plane containing the pelvic origin AB. 

 This angle, according to the Postulate, ought to be 45 0 ; its 

 mean value is 47 0 2i ; , which is a very remarkable approxima- 

 tion in observations of this kind. 



