4-16 Mr. F. O.Ward's Physiological Remarks 



tions of lifting and hammering which they respectively per- 

 form, but it is so j)roportioned to the leverage of the triceps, 

 that the two muscles cooperate harmoniously in the action of 

 striking a blow forward; unequal spaces being traversed and 

 unequal resistances overcome, in the same period of time, so 

 that the resulting position of the limb is precisely the one re- 

 quired : while the strength of the one set of muscles bears 

 such proportion to that of the set with which it acts in concert, 

 that both remain unfatigued for the same number of ac- 

 tions. 



It is this £?/ue?s//ferf adaptation of parts, which forms the chief 

 characteristic of the mechanism of Nature. Working with 

 unlimited means, she yet works with scrupulous oeconomy; in 

 her structures no power is redundant, nor a single advantage 

 lost; so that, however completely an arrangement may sub- 

 serve one primary purpose, we find, upon renewed examina- 

 tion, an equally accurate adjustment to several secondary 

 ends. 



When the means of estimating with precision the contractile 

 force of the muscular fibre, are obtained, I have no doubt that 

 these compound relations of power, lever, and motion pro- 

 duced, will form an interesting study*. 



Magendie f observes, that the intensity of muscular contrac- 

 tion depends partly upon certain peculiarities in the organiza- 

 tion of the fibres, such as size, firmness, colour, &c., and partly 

 upon the energy of the cerebral influence, or the "puissance 

 de volonte," by which they are excited to action. Muscles ac- 

 quire far more than their ordinary power, during those affec- 

 tions of the mind which stimulate the brain to strong action, 

 such as rage, madness, &c., and also during certain convulsive 



* Borelli in his posthumous work De Motu Animalium, published in 

 1680, has entered into an elaborate analysis of the mechanical relations of 

 the body, with a view to determining the absolute force of the muscler-. 

 But unfortunately his experimental data (see, for instance. Pars prima, 

 cap. 8,) are as loose and unsatisfactory as the subsequent calculations are 

 minutely accurate; and his reasonings are interwoven with a purely specu- 

 lative hypothesis of the nature of muscular fibre, which he supposes to 

 consist of minute rhomboidal vesicles, contractile by inflation. By these 

 means he brings out very startling results. Thus to the flexor longus 

 polHcis manus alone, he attributes a tractile force of 3720 pounds ; to the 

 deltoid of 61,609 pounds; to the intercostals of 32,040 pounds ; to the 

 glutasi of 375,420 pounds, &c. (see cap. 17, prop, cxxiv. et seq.) Dr. Bos- 

 tock considers his estimate of the force of the muscles of the thumb to be 

 a hundred times too great. He has not noticed the twisted tendon of the 

 pectoral in man, nor calculated its force and leverage. The only remarks 

 upon its strength I can discover, are in cap. 22, prop, cciv., where, from its 

 small relative size, he proves it to be impossible " ut homines piopriis viri- 

 bus artificiose volai'e possint." 



t Physiologie, vol. i. p. 275. 



