374 



ANIMAL MECHANICS. 



Abduction Muscles of Lions Hip— Difference between Theory 

 and Observation. 



Muscle. 



Weight 



of 

 Muscle. 



Distance 

 between cal- 

 culated and 

 observed axes. 



r. Agitator caudse, .... 



2. Glutaeus primus, .... 



3. Tensor vaginae femoris, . 



4. Glutseus secundus (a ), . 



5. Gluteus secundus ((3), . 



6. Glutceus tertius, .... 



7. Glutaeus quartus, 



8. Obturator internus, . 



6. 50 oz. av. 

 3-5o „ 

 6 -5° „ 

 2.50 „ 

 14.50 „ 

 2-50 „ 

 o.53 » 

 4.00 ., 



0. 23 in. 

 0.40 „ 

 0.25 .. 

 O. 16 „ 

 0.21 „ 

 0.18 , 

 O. 19 „ 

 0. 10 „ 





40.53 oz. av. 



0.215 in. 



The mean difference between calculation and observation 

 amounts to only 0.215 of an inch, being less than one-third of 

 the total range (0.71 in.) permitted to the axis of rotation by 

 the arrangements of the joint. 



The foregoing mean error is calculated as the arithmetical 

 mean of the error in each muscle, or, in other words, all the 

 muscles are treated as of equal importance. The work 

 actually done by each muscle is, however, proportional to its 

 weight, and we may calculate the mean error, taking into 

 account the relative importance of each muscle, as measured 

 by its work actually done. In order to find this mean, we 

 multiply the weight of each muscle by its error, and divide 

 the sum of all the products by the total weight of all the 

 muscles. We thus find — 



