. The American artist's manual; . rm, the arm op mustbe part of a cycloid, the radius of whosegenerating circle is equal to the length ofthe arm DH, reckoning from its extremi-ty Ii,or the centre of the roller, to the cen-tre of the axle DC. But when a roller isfixed upon the extremity H, we must drawa curve parallel to the cycloid, and with-out it, at the distance of the rollers semi-diameter ; and this curve will be the pro-per form for the arm op It is evident thatwhen this mode of raising the piston isadopted, the a>m DH must be bent as inthe figure, otherwise the extremity pwould preve
. The American artist's manual; . rm, the arm op mustbe part of a cycloid, the radius of whosegenerating circle is equal to the length ofthe arm DH, reckoning from its extremi-ty Ii,or the centre of the roller, to the cen-tre of the axle DC. But when a roller isfixed upon the extremity H, we must drawa curve parallel to the cycloid, and with-out it, at the distance of the rollers semi-diameter ; and this curve will be the pro-per form for the arm op It is evident thatwhen this mode of raising the piston isadopted, the a>m DH must be bent as inthe figure, otherwise the extremity pwould prevent the roller H, from actingupon the arm op. In Fig. 6. we have another method ofraising a weight perpendicularly with auniform motion. Let AH be a wheel mov-ed by any power which is sufficient toraise the weight MN by its extremity O,from O to e, in the same time that thewheel moves round one-fourth of its cir-cumference, it is required to fix upon itsrim a wing OBCDEH which shall producethis effect with a uniform effort. Divide. MEC MEC the quadrant OH into any number of equalparts Om mn, &c. the more the better,and oeinto the same number ob, be, cd, & through the points m, n, p, H, drawthe indefinite lines AB, AC, AD, AE, andHhke AD equal to Ab, AC to Ac, AD toAd, and AE to Ae; then through thepoints U,B,C,D,E, draw the curve OBCDEwhich is a portion of the spiral of Ar-chimedes, and will be the proper form forthe wiper or wing- OFIB. It is evident thatwhen the point m has arrived at O, theextremity of the weig-ht will have arrivedat b; because AB is equal to Ab, and forthe same reason when the points n, p, IIhave successively arrived at O, the extre-mity of the weight will have arrived at thecorresponding- points c, d, e. The motiontherefore will be uniform, because thespace described by the weight is propor-tional to the space described by the mov-ing power, Ob being to Oc as Om to 0? it be required to raise the weight MXwith an accelerated or retarded motion,we ha
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