23 



The Rev« S. Haughton on some Elementary [June 20_, 



small. I therefore compared the sections of the Biceps Jimieri and 

 BrachicBus, found bj me, with the only other measurements, with 

 which I am acquainted, for the knowledge of which I am indebted 

 to Dr. W. Moore of Dublin, who translated the results for me, from 

 the Dutch, of Messrs. Donders and Mansfelt * of Utrecht. 



Cross Sections of Mceps humeri and BracJiiceus. 



millims. sq. in. 



1. Biceps Tiimeri (long head) 530 0-821 



(short head) 452 0-701 



2. Brachicdus . 614 0-952 



1596 2-474 



If this estimate of the cross section of the muscles be assumed in- 

 stead of my own, the coefficient found by me should be increased in the 

 proportion of 3190 to 2474 ; or 



Coefficient of muscles of fore arm . . . 94'7 X ?i??= 122 lbs. 



2474 



The mean of the coefficients found from my own measurement of the 

 muscles of the arm, and that of Professor Donders, is 108-4 lbs., which 

 agrees nearly with that obtained from the muscles of the leg, viz. 

 110-4 lbs., and the mean of all the observations on arm and leg would 

 be 109*4 lbs., a result which I consider to be not far from the truth. 



The cross sections of the muscles were found by cutting them across 

 with a sharp scalpel, and marking out their section on cardboard, and 

 afterwards weigliing the marked portions, the weights of which were 

 then compared with the weight of a known number of square inches of 

 the same cardboard, and so the cross sections in square inches calculated. 



I give here, for the purpose of illustration, the actual sections of the 

 muscles of the leg. (Figs. 1-6.) 



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. 



oz. 



5. Semimembranosus . 7*25 



6. Gracilis .... 2-98 



7. Sartor ius . . . . 5-66 



1. Biceps humeri . . 4*22 



2. BrachicBus .... 5*04 



3. Biceps femoris . . 10-74 



4. Semitendinosus . . 5 '17 

 ii. The principle of economy of force or of material in nature would 



lead necessarily to the principle that each tendon conveying the eifect 

 of a force to a distant point should have the exact strength required, and 

 neither more nor less ; for, according to the doctrine of Jinal causes, it 

 was originally contrived by a perfect architect, and according to La- 

 ^ Over de Elasticiteit der Spieren. Utrecht, 1863. 



