MOTION. 
By table 13 we find that the 
duration of the step in leaping 
is less than in slow walking,* 
but greater than in running ;t+ 
the length of step is much 
greater than in walking, and 
may be made greater than in 
quickest running. As the 
body swings freely in the air 
a longer period, and rises to a 
479 
greater elevation in leaping 
than in running and walking, 
it is necessary that the projec- 
tile force should be made 
greater, but the time during 
which the extensor power of 
the leg acts, although very 
short, is of intense action; 
' wr, 
ay, 
Niner 
foe, 
ig 
Figures designed by Weber to illustrate the formulas for leaping. 
hence, it is not easy to regulate the amount 
of muscular action as in walking and run- 
ning, and consequently it may be too great or 
too little for the object in view. The vertical 
undulations also are much more considerable 
than in the other modes of locomotion. 
In descending rapidly the sides of steep hills 
it is much safer to do so by leaping than by 
running, as in the former mode of progression 
the foot is placed on the ground at the end of 
each step in a position favourable for stopping, 
which cannot be done in the latte. MM. 
Weber consider that the study of the laws 
which regulate the locomotion of man, and of 
the mechanism by which it is accomplished, 
will assist mankind in the construction of au- 
tomatic locomotive machines. Mr. G. Rennie 
has studied the construction of animals and the 
principles on which they move with a view of 
applying them to the locomotion of the steam- 
boat, on the supposition that animals move in 
air, in water, with the least expenditure of mus- 
cular force, an hypothesis which accords with 
* See Table 8. + See Table 12, 
our views as wellas those of M. Dumas, who 
considers that man is capable of moving and 
producing a greater mechanical effect, with 
less expenditure of fuel, than can be produced 
by any steam-engine hitherto invented. 
In every mode of progression there is a sen- 
sible increase of action in the circulating and 
respiratory systems ; but the effect produced on 
them is much greater in running and leaping 
than in walking. In the two former cases a vio- 
lent palpitation of the heart and hurried respira- 
tory movements are quickly produced, on which 
account they cannot be very long continued. 
In running, when four steps are taken in 
a second, the difficulty of breathing soon 
causes the pedestrian either to slacken his pace, 
or what may be most advantageously substi- 
tuted when it is desirable to continue nearly the 
same speed, and at the same time preserve the 
breath, to exchange the running for a leaping 
movement. In consequence of the deliberate 
manner in which the steps may be taken in 
leaping, the breath may be preserved for a longer 
period, and the action of the heart diminished ; 
