(58 



ANIMAL MECHANICS. 



The perpendiculars let fall upon the directions of the 

 muscles were measured by stretching strings from the origin 

 to the insertion of the muscles, and measuring, by means of a 

 compass, the perpendiculars let fall upon these strings from 

 the axis of the joint. 



The weights of the muscles themselves were as follows : — 



oz. 



1. Biceps humeri, 4.22 



2. Brachi&us, 5.04 



3. Biceps femoris, . . . .10.74 



4. Semitendinosu*, . . . . 5.17 



5. Semimembranosus, . . . 7.25 



6. Gracilis, 2.98 



7. Sartorius, . . . . . 5.66 



From the preceding facts, we may infer the total force of 

 the flexors of the leg, by multiplying their total cross section, 

 9.33 sq. inches, by the coefficient of contraction, 1 10.4 lbs. 

 Total force of flexors of leg = 9.33 x 110.4 = 1030.03 lbs. 



The whole investigation illustrates well the difficulties 

 that surround researches in Animal Mechanics. I was obliged 

 to make the observations and measurements on three different 

 subjects : — 



(a) . The maximum weights were observed by trials made 

 upon myself and a friend of a similar height and strength, 

 with results closely agreeing. 



(b) . The measurements of the arms of the levers were 

 made upon the skeleton of a Frenchman, of the same height 

 and length of bones as myself. 



(c) . The cross sections of the muscles of the arms and 

 legs were measured on a blacksmith who had died of cholera, 

 and who, when living, was a much more muscular man than 

 myself, with probably, also, a greater developement of muscles 



