124 



ANIMAL MECHANISM. 



each instant. But we know that these shocks are very un- 

 favourable to the full utilization of mechanical force ; we have 

 explained (page 49) the inconvenience which would arise 

 from them in the work of living motive agents, and the 

 manner in which these shocks are lessened by the elasticity 

 of muscular fibre. 



Under the conditions in which a man dragging a load is 

 placed, if he is attached by a rigid strap to the mass which 

 he has to draw, the shocks of which we have spoken will be 

 produced, and he will feel their reaction on his shoulders. In 

 order to avoid these painful jerks, and to utilize more fully 

 the effort which he makes, we have placed between the car- 

 riage and the traction strap an intermediate elastic portion, 

 the effect of which has answered our expectations. 



We are endeavouring to construct analogous contrivances, 

 which may be adapted to the traces of ordinary carriages, so 

 as to lessen the violence of the pressure on the collar, and to 

 utilize more fully the strength of the horse. 



CHAPTER III. 



THE DIFFERENT MODES OF PROGRESSION USED BY MAN. 



Description of the apparatus for the purpose of studying the various modes 

 of progression used by man — Portable registering apparatus— Experi- 

 mental apparatus for vertical reactions —Walking — Running —Gallop 

 — Leaping on two feet and hopping on one — Notation of these various 

 methods— Definition of a pace in any of these kinds of locomotion 

 — Synthetic reproduction of the various modes of progression. 



The principal modes of progression employed by animals, 

 are walking ^ which we have already described at some length 

 as far as it relates to man, running at different rates of speed, 

 the gallop, and leaping on one or two feet. 



The act of walking varies according to the nature or the 

 slope of the ground ; we shall have to treat of these different 

 influences. 



In this new study it is no longer possible to employ the 



