Mechanic Powers. 237 



burden the greater share he bears of it ; and if 

 he goes directly under it, he bears the whole. So 

 if one man is at G, and the other at B, having 

 the pole or stick AB resting on their shoulders; 

 if the burden or weight W is placed five times 

 as near to the man at G, as it is to the man at B, 

 the former will bear five times as much weight as 

 the latter. This is likewise applicable to the 

 case of two horses of unequal strength to be so 

 yoked, as that each horse may draw a part pro- 

 portionate to his strength ; which is done by so 

 dividing the beam they pull, that the point of 

 traction may be as much nearer to the stronger 

 horse than to the weaker, as the strength of the 

 former exceeds that of the latter. 



To this kind of lever may be reduced oars, 

 rudders of ships, doors turning upon hinges, 

 cutting-knives which are fixed at the point of 

 the blade, &c. 



The third kind of lever is when the power is 

 placed between the weight arid the prop. An 

 example of this kind of lever you see when a 

 man raises a long ladder to place it against a 

 wall. It is obvious that this kind of lever, so 

 far from assisting human strength, requires a 

 power much greater than the weight to be raised. 

 For let E (fig. 97.) be the prop of the lever AB, 

 and W, a weight of one pound, placed three 

 times as far from the prop, as the power P acts 

 at F by the cord C going over the fixed pulley 



