442 



ANIMAL MECHANICS. 



long lapse of time, and without the aid of a Contriving Mind, 

 I would ask him to study the remarkable words of Cicero : — 

 " Nihil est enim, quod ratione et numero moveri possit, 

 sine consilio ; in quo nihil est temerarium, nihil varium, nihil 

 fortuitum." 



13. Applications of General Laws of Muscular Action. — 



I shall conclude my observations on Animal Mechanics by 

 laying down in this section a few General Laws, and showing 

 the inferences that may be deduced from them. In drawing 

 these inferences, I have the advantage of being able to make 

 use of the experiments of Mr. W. Stanley Jevons,* of Man- 

 chester, and of Mr. Frank E. Nipher,f of Iowa University, 

 U. S. A., in addition to my own experiments and observa- 

 tions ; and I believe it will be admitted, from the results of 

 the investigations I have been able to make, that a great 

 future in the way of useful practical applications lies open to 

 the Science of Animal Mechanics. 



I have been led to the establishment of the three following 

 Laws, the proofs of which I shall give in detail :— 



Law I. — In comparing together different muscles, the work 

 done in contracting is proportional to the weight of each. 



Law II. — In comparing the same muscle (or group of 

 muscles) with itself when contracting under different external 

 conditions, the work done is always constant in a single con- 

 traction. 



Law II L — When the same muscle {or group of muscles) is 

 kept in constant action until fatigue sets in, the total work done, 

 multiplied by the rate of work, is constant. 



I shall now take these Laws in order, and show the evi- 

 dence on which each is based. 



* Nature, 30th June, 1870, page 158. 



f School Laboratory, September and December, 1871, Iowa City, page 108. 



