* Rey. S. Haughton on Animal Mechanics. 295 
1. Biceps femoris (long head) . . . 2°59 sq. in. 
ps (iborameea) . =. . Lit ~, 
- oerenmaosue es... 187 OC, 
3. Semimembranosus . . . . . . 225 ,, 
OMe ye OBO, 
ree SO ee . .s OF9 ,, 
9°33 
When the arm was held vertically, and the forearm horizontally 
with the fist shut and in supination, I found that 39 Ibs. was the 
limit of the weight that could be lifted when suspended at 127 
inches from the axis of the elbow-joint, and that the perpendi- 
culars let fall upon the directions of the muscles from the same 
axis were :— 
_ 1. Biceps humeri fone ees 30 Oe: SHCHES, 
eens, eee AO 
Hence if K denote the force of the muscle, per square inch of 
cross section, we have, adding 2 lbs. for the weight of the forearm 
at 124 inches from the axis of the joint, 
a 191 x 2°06 
41 lbs. x 12} inches=K x | +1-28 x 1:07 } 
5023=Kx | 3935 } 
and finally . ##K=94-7 Ibs. 
This represents the force per square inch of cross section that 
the muscles flexing the forearm are capable of exerting. 
In order to measure the force of the muscles flexing the leg, I 
placed the observer lying upon his face upon a table, with the 
legs extended over its edge, and having fastened down the 
thighs, I observed the maximum weights, suspended from the 
heel that could be conveniently lifted, and found that 34 lbs. was 
the limit; to this must be added 3 lbs. for the weight of the leg, 
Supposed suspended at the heel, which was measured as 164 
inches from the axis of rotation of the knee-joint. The perpen- 
diculars let fall upon the directions of the several muscles flexing 
the leg were then measured :— 
Perpendicular. 
1. Biceps femoris (long head) . . . . 0°95 in. 
S (short head). . . . .0°56,, 
2. Semitendinosus pees eS Or, 
3. Semimembramosus ...... . 065,, 
MONEE. 6 Se ODE, 
eT ETONE 56s, ore ee ew « O00 ,,, 
Hence we find, for the determination of K (the coefficient of 
muscular contraction per square inch of cross section), 
