444 



ANIMAL MECHANICS. 



flow from it. In my section on Muscular Types I have en- 

 deavoured to show what valuable applications may be made 

 of this Law by the Comparative Anatomist, when combined 

 with the Law of Least Action applied to muscular structure 

 and arrangements. 



Law II. Constancy of Work done. — The second Law may 

 be described as the law of constancy of work done by a group 

 of muscles, in a single contraction, performed under different 

 external conditions. 



The admirable experiments published by Mr. W. Stanley 

 Jevons in Nature (30 June, 1870) enable me to demonstrate 

 the truth of this Law in a satisfactory manner. 



Mr. Jevons ascertained by numerous experiments the 

 comparative distances to which various weights could be 

 thrown by hand, on level ground. The weights employed 

 ranged from J lb. up to 56 lbs., and were thrown as nearly as 

 possible in a uniform manner, and at the most advantageous 

 angle of projection. About 57 experiments at different times 

 were made with each weight, or 456 experiments in all; and 

 it was quite obvious that good average results were obtained, 

 the correspondence of different sets being very satisfactory. 

 The following results were obtained : — 



Mr. Jevons Experiments (Throwing Weights). 



Weight in lbs. 



Average Distance 

 thrown in feet. 



Calculated. 



Difference. 



56 



1.84 



1-93 



+ 0.09 



28 



3-70 



3.<>3 



- 0. 07 



*4 



6.86 



6.46 



- 0. 40 



7 



10.56 



10. 61 



+ 0.05 



4 



14. 61 



14.65 



+ 0.04 



2 



18.65 



19.61 



+ 0.96 



1 



23-°5 



23.61 



+ 0.56 



4 



27.15 



26. 30 



- 0. 85 



