Chap. 34.] Force of Mafcks. 351 



city is loft in force, it muft be remarked, is applica- 

 ble to this cafe, fo that fome lofs of frrength necefTarilf 

 attends the acquiiition- of fuperior celerity. But this 

 inconvenience has been obviated by a very fimple ex- 

 pedient, that of making the mufcle ftronger than would 

 otherwife have been neceffary. 



Many very erroneous calculations have been made 

 with refpect to the force of mufcles: Borelli has been 

 led to conclude that the heart at every contraction 

 -exerts a force equal to ioo,ooolb. while others have 

 pretended to difcover that this force does not amount 

 to many ounces. With refpect to the heart, however, 

 we really have not data on which we can proceed with 

 any tolerable degree of precifion. There is no mufcle 

 in the body more conveniently fituated for having the 

 force of its contraction determined than the biceps of 

 the arm. It will be foreign to our prefent purpofe 

 to mention all the fteps of the calculation, with the 

 grofs refult of which I fhall in this place prefent the' 

 reader ; it is indeed merely mentioned a probable, 

 that when we raife forty pounds weight by means of 

 the fore-arm, the biceps exerts a force at leaft equal to 

 five or fix hundred pounds. 



The furprizing mufcular force of the turkey's giz- 

 zard, has been already noticed. 



From thefe obfervations, it appears, notwithftand- 

 ing the great vifible exertions of mufcular force, that 

 the greater part of their real power produces no ap- 

 parent effect. For all mufcles are inferted nearer the 

 center of motion than the weights on which they act, 

 and their effect is therefore lefs in proportion to the 

 ftiortnefs of the lever on which they act. In moft of 

 She limbs the mufcles are inferted at very acute angles, 

 which throws their force more nearly in the direction 



Pf 



