ANIMAL MECHANICS. 



69 



of arm than of leg. It is very difficult to obtain exact results 

 from observations necessarily involving so many sources of 

 error ; and yet I venture to think that the mean of my two 

 sets of observations cannot be far from the true contractile 

 force of the muscles : — 



Coefficient of flexors of arm, . . 94.7 lbs. 

 Coefficient of flexors of leg, . . 11 0.4 ,, 



Mean, . . . I02.55lbs. 



It has been already stated, on the authority of Donders 

 (p. 2), that the cross section of the flexors of the forearm con- 

 tains 798000 muscular fibres, having each a diameter of 3 Jo tft 

 of an inch ; from which number, and the preceding data, we 

 may readily find in grains, the 



Muscular force of con- 

 traction of a single 

 muscular fibre, 



Other observers have found coefficients for he force of 

 human muscles, referred to the unit of cross section, which 

 differ somewhat from the coefficient deduced above. 



Weber m&de some experiments on this subject, from which 

 he deduced the force of gastrocnemius and solceus to be 

 1 kilogram per 1 sq. centimeter. 



Henke and Knorz corrected the calculation of Weber, and 

 found that his result should have been 



4 kilograms per sq. centimeter. 



Their own experiments gave for the biceps, brachialis inter- 

 nus, and supinator longus, of the right arm — 



8.991 kilograms per sq. centimeter; 

 and, for the mean of the two arms, 



8.187 kilograms per sq. centimeter. 



3. IOO x 102. C C x 7000 



^— X — — - 2.87 grs. 



798000 ' & 



