ANIMAL MECHANICS. 



63 



The last two columns of Table VIII. measure the respi- 

 ratory distress produced by different kinds of labour ; and 

 show that Coignet's lift is more than thrice as severe as 

 ordinary labour ; and that running at 8 miles an hour with a 

 load equal to half the weight of the body is more than twice 

 as severe as pulling a boat race. 



5. On the Absolute Force of Muscles. — We have already 

 considered the amount of work given out by muscles, when 

 employed either statically or dynamically ; and it now re- 

 mains to investigate their absolute force when employed for 

 an instant, or very short space of time. 



Example, No. i. — Flexors of the Forearm. In order to de- 

 termine the force of the flexors of the forearm, I held my 

 arm vertically, and the forearm horizontally, with the fist shut 

 and in supination, and found that 39 lbs. was the limit of the 

 weight I could just raise, when suspended at 12J inches from 

 the axis of the elbow joint ; this gives 



The moment of Force applied = 41 x 12^=5025; 



estimating the forearm itself as equivalent to 2 lbs. suspended 

 at 12J inches from the joint. 



I endeavoured to ascertain the moment of the muscles by 

 dissecting a very finely-developed subject,* who had been a 

 blacksmith by trade, with the following results : — 



Cross Sections of Muscles. 



1. Biceps humeri, . . 1.9 14 sq. in. = 12.346 sq. cent. 



2. Brachiceus, . . . 1.276 ,, = 8.230 „ 



In order to find the perpendiculars let fall upon the direc- 

 tions of the muscles in my own arm, I selected another sub- 



* This was the same subject on which I made the measurements of the leg 

 muscles described subsequently. 



