30 



ANIMAL MECHANICS. 



in making this estimate, we have no difficulty, as before, 

 in finding the portions of muscles employed, for they are 

 perfectly well defined ; at the same time, it may be considered 

 that the muscles now under investigation are not in them- 

 selves so well adapted as the muscles of the shoulder, to give 

 an average result, as they differ more widely in one man as 

 compared with another, than the shoulder muscles are found 

 to do. This difference is caused by the more varied uses of 

 the forearm, and of the muscles actuating it, than of the 

 muscles of the shoulder that hold the entire arm horizontal. 



The results obtained by me from well-selected subjects are 

 contained in the following Table : — 



Table VI. — Weights of Muscles employed in holding the Fore 

 arm horizontal, with the Palm upwards : — 





Biceps. 



Brachiseus. 



Supinator radii 

 longus. 



A. Female, 



B. Male, 



C. Male, 



D. Male, 



E. Male, 

 P. K. Male, 



2.30 oz. av. 

 3-9 1 » 

 3- 2 4 >> 

 4.00 „ 



i-93 » 

 5-9° » 



2.74 oz. av. 

 4.01 ,, 

 4-30 „ 



1.66 „ 



0.75 oz. av. 

 1 .40 „ 

 a. 30 „ 



Means, 3.54§ oz. av. 



3.l7f oz. av. 



1.481 oz. av. 



Hence we find that the average total weight of the muscles 

 employed in holding the forearm horizontal is 8.2075 oz. av. 



From the preceding result as to the average weight of the 

 muscles acting on the forearm, combined with Table V., and 

 assuming tj to be equal to unity, we find — 



Work done by muscles"^ 



holding the loaded Fore- I 4886.76 „ „ 



? . , „ > = -~ = 1.028 ft. lbs. 



arm horizontally, perl 579*8.2075 



ounce, per second, J 



