MECttANIC POWER. 2^ 



fure it cannot be called repulfion, but to proceed, " and heMeafureof 



... , , . c . mechanic power 



continues this action as long as he continues to lupport it, of effeft. 



and we know, that if this body were at the end of a horizon- 

 tal arm turning round a vertical axis, the fame effort which the 

 man exerted in merely carrying the weight, if now exerted on 

 the body by pufliing it horizontally round the axis, will gene- 

 rate in it the fame velocity which gravity would generate by 

 its falling freely.'* 



A more erroneous proportion was never introduced to the 

 theory or practice of mechanics. What, is there no difference 

 in a man carrying a load on his (boulder, and putting it into 

 a truck ? or to come nearer the Profeifor's proportion, let the 

 man who has to carry two hundred pounds for one mile be 

 permitted to take the weight from his (boulders, and reft it on 

 the arm of any thing like a horfe wheel, perfectly detached 

 from the mill gear, let the gudgeons be oiled, and then let 

 bim ** pujh'* it hcriizontally round its axis until "Re has travelled 

 a mile. 



Now without a(king the man which he likes be(^, let us fee 

 what he does by plaoing his load on the arm of the horfe* 

 wheel, and puftiing it round. Why, he certainly overcomes 

 the additional friftion which his load has added to the weight 

 of the wheel, and that is all, and if you will let us have 

 gudgeons which have no friftion, the man need not to walk 

 far to puQi the horizontal arm into perpetual motion. 



But now for the monftrous conclufion by this propofition. 

 '< If the man's exerlion was employed to generate motion in- 

 ftead of counteracting gravity, he would generate daring that 

 minute the fame motion that gravity would; that is C0x?2 

 feet velocity per fecond in a mafs of 30 pounds. There 

 would be 30 pounds of matter moving with the velocity of 

 1920 feet per feoond. We would exprefs this production 

 or eflfeft by 30 x 1920, or by 57600 as the meafure of the 

 man's exertion during the minute." 



Here is evidently a typographical error, fecond for minute, 

 but when we admit fuppofitions for the fake of illuftraXion, 

 there ought to be fome conformity in the fuppotition to the 

 fa£t it is intended to iiluftrate: then I would a(k, wheref's 

 the man who can generate 32 feet of velocity in a mafs tti 

 SO pounds in one ftcond ? to be fure he can let it fall a fecond, 

 but he cannot 4^arrj' it 32 feet in a (econd ; but he fays, " we 

 4 would 



