LEVERAGE OF BONES. 463 
verses a space equal to 5 in one second ; the extremity r of 
the lever will traverse a space equal to 25 in the same time, 
its distance from the fulcrum a being five times as great as 
that of the point c from the fulerum. Hence, although, to 
raise a given weight at 7, a power more than five times its 
amount must be applied at c, that power will raise the weight 
through a space five times as great as that through which 
itself passes in the same time. Thus, what is lost in power is 
i in time; and the shortening of a muscle, small in 
amount, but effected with sufficient power, causes the raising 
of a weight through a considerable space. 
615. We shall find that this is the case in regard to most 
of the muscular actions in the animal economy. Thus, the 
fore-arm (fig. 219, 6, c) is bent upon the arm a by a muscle d, 
Fig. 219. 
_ which arises from the top of the latter, and which is inserted 
at e, a short distance from the elbow-joint. Hence its con- 
_ traction to a very slight extent will raise the hand through a 
considerable space ; but a proportional increase in its power 
will be required to overcome any resisting force in the hand. 
—The arm is straightened again by an antagonist muscle, 
which lies on the back of the arm, and which is attached to a 
short projection made by one of the bones of the fore-arm 
behind the elbow: this muscle also operates at a similar dis- 
advantage in regard to power, and advantage in point of time, 
‘in consequence of its point of attachment being so near to the 
fulcrum. In responding to its action, however, the bones of 
_ the fore-arm constitute a lever of the “first order ;” the elbow- 
_ joint, which serves as the fulerum, being now between the 
_ power and the resistance. 
