37S PHILOSOPHICAL 'J'BANSACTIONS. [aNNO 1730. 



last rope is that wliich raises the weight. x\t the other end of the axle 

 there is a large wooden wheel like a pulley, hh, about which is wound a 

 long rope n. 



To work this engine; pull the long rope n, which causing the great wheel 

 to turn, also carries round the barrel, which is made fast to it. This axle, as 

 it turns round, causes the ropes ee to wind about it, by which the axle and 

 the wheel rise, while the rope f, to which the weight is fastened, also winds 

 itself up on the axle the contrary way; and this double winding up of the 

 ropes causes both the burthen and the axle and wheel to rise at the same time. 

 Now it is evident, that all this rise is performed without the friction of any 

 part, and consequently the whole power, which draws the rope n, is employed 

 without any hindrance; which cannot be in other engines. 



It may be objected that the power which acts at n, must, besides the weight, 

 raise also the axle and great wheel, and that their weight is one of those ob- 

 stacles which Aristotle says all engines are liable to; and that this obstacle is 

 equivalent to the friction which is in other organs. But it may be answered, 

 that friction is an obstacle wholly unavoidable in all other organs; but that it 

 is easy to remedy the obstacles of this, which is done by means of the heavy 

 body M, taken equal in weight to the great wheel and axle, which it sustains 

 by means of the rope ii, which running over the pulleys ll, is fixed to the 

 ring or collar k, that goes round the axle f. For the axle and the wheel being 

 counterpoised by this weight, the power which acts by drawing the long rope 

 N, acts for raising the weight only. The experiment which was made with 

 this engine has confirmed the truth of this problem, by comparing its effects 

 with those of a crane, in which the proportion of the size of its axle to the 

 circumference of the wheel, was the same as in this machine: for in the crane, 

 a weight of one hanging at a rope going about the wheel, drew up a weight of 

 7, when it had one half added to it, to make it preponderate, or give motion 

 to the power: and when the weight to be raised, and the weight which served 

 as a power, were proportionably increased, there \\as also a necessity to increase 

 the additional weight, which made the power preponderate, in the same pro- 

 portion: so that as it was required to add one half to the power when the 

 weight was 7, the addition to the power became one for a 14lb. weight, 2 for 

 a 28lb. 4 for a 50lb. and so on; because the resistance from friction increases 

 nearly in the same proportion that the weights are increased. But this did not 

 happen to my engine, in which one quarter was always sufficient for the draught, 

 or to make the power preponderate, not only when the weight was 7, but also 

 when it was I4lb. 28lb. 561b. &c. which evidently bhows that this engine acts 

 without friction." 



