MOVING POWERS IN MACHINERY. DO 



inclines upwards, making a small angle with the 

 horizontal plane. 



A horse drawing a weight over a single pulley, 

 can draw 200 lbs. for eight hours a day, and walk- 

 ing at the rate of L 2i miles in an hour, which is 

 about 3-£- feet in a second; and if the same horse be 

 made to draw 240 lbs., he can work but six hours a 

 day, and cannot go quite so fast. To this may be 

 referred the working of horses in all sorts of mills 

 and water-works, w T here we ought to know, as near 

 as we can, how much we make every horse draw, 

 that we may judge of what the effect will be when, 

 proper allowance shall have been made for all the 

 frictions and hindrances, before we cause any ma- 

 chine to be erected. 



When a horse draws in a mill, or gin of any 

 kind, great care should be taken that the horse- 

 walk, or circle in which he moves, be large enough 

 in diameter, otherwise the horse cannot exert all 

 his strength; for, in a small circle, the tangent 

 in which the horse draws deviates more from the 

 circle in which he is obliged to go, than in a 

 larger circle. The horse-walk should not be less 

 than 40 feet in diameter, when there is room for it. 

 In a walk of 19 diameter, it has been calculated 

 that a horse loses two-fifths of his strength. 



The worst way of applying the force of a horse 

 is to make him carry or draw up hill ; for, if the hill 

 be steep, three men will do more than a horse ; 

 each man loaded with 100 lbs. will move up faster 

 than a horse that is loaded with 300 lbs. This is 

 owing to the position of the parts of a man's body, 

 which are better adapted for climbing than those 

 of a horse. 



As a horse, from the structure of his body, can 

 exert most strength in drawing almost horizontal ly 



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