Schemes for Pcrpitiial Motion. 379 



centre of the macliine, and that in machines very little compounded it is poflible to pro- 

 duce effefts direftly contrary to the rule which is true of the fimple lever, they would 

 probably renounce many flattering projefts, grounded only on the fuppofition of its univer- 

 fality. Defaguliers contrived an apparatus in which two equal weights may be placed at 

 any diftance whatever from the centre of motion, and ftill continue in equillbrio. Fig. 3 

 reprefents this inftrument, AD denotes a balance with equal arms, and EF another of the 

 fame dimenfions. Thefe move on the centres B and C, and are connefted by the inflexi- 

 ble rods AE and D,F ; the motion being left free by means of joints at the corners. Acrofs 

 the rods AD, EF, are fixed two bars IK, LM. Now it is unneceflary to fliew that the 

 weight G will defcribe exadly the fame line or circular arc, when the levers are moved into 

 the pofition a d f e, or any other pofition, as it would have defcribed in cafe it had been fuf- 

 panded at A, or K, or E ; and that it is of no confequence in this refped at what part of the 

 line AE, or IK, it be fixed. The fame obfervations are true of the weight H on the other 

 fide. And accordingly it is found, that thefe equal weights may be fufpended any where 

 on the lines IK and LM without altering their equilibrium. 



By this contrivance it is moft evidently proved, to thofe who are totally unacquainted 

 with the theory, that weights do not preponderate in compound engines, on account of their 

 diftance from the centre. Several other contrivances may be made to the fame efFe£t. The 

 following combination of wheel- work prefented itfelf to me asone which would mod probably 

 be miftaken for a perpetual motion. Fig. 2. Plate XV. The five circles reprefent the fame 

 number of wheels, of equal diameter and number of teeth, a£ling together. The middle 

 wheel A is fixed between two upright pillars, fo that it cannot levolve. The other four 

 wheels are pinned in a frame HI, in which they can revolve, and through which the axis 

 of A likewife pafles. From the extremity of the axis of D, and alfo of d, proceed the ho- 

 rizontal levers HK and IL, which are equal, and point in the fame diredion parallel to the 

 plane of the wheels. At the extremity of thefe arms hang the equal weights P and p. 

 Let it now be imagined that the end I of the frame is depreflisd ; the wheel B will turii 

 round by the re-a£tion of the fixed wheel A in the fame dire£lion as HI, and ic will make 

 one revolution, in the fame time, relative to the frame, or two with regard to abfolute fpace 

 by reafon of its being carried round. The a£lion of B upon D will produce a rotation re- 

 lative to the frame in the oppofite direftion during the fame time. Inftead therefore of 

 two revolutions, like the wheel B, this wheel D, with regard to abfolute fpace, will not re- 

 volve at all, and in every pofition of the apparatus the arm IL will continue horizontal, 

 and point the fame way. For fimilar reafons the arm HK will retain its pofition. Con- 

 fequently, it is fecn that the defcending weight will move at a great horizontal diilaiice from 

 the centre N, while the afccnding weight rifes very near that centre. But there will not 

 on this account be a perpetual motion : for the adlions of the levers HK and IL upon the 

 frame HI, by means of the toothed wheels, will in the detail be found precifely alike, and 

 in the general confideration of the motions of P and p, the oppofite motions in the circle 

 E F G will be accurately the fame. 



It lias always been confidercd as efTential to a perpetual motion, that it fliould be derived 

 from fome energy which is not fuppofcd to vary in its intcnfity. Such arc the inertia, the 

 gravity or magnetifm of bodies. For an occafional or periodical variation of intcnfity in 

 any force is evidently produdivc of motion, which requires only to be accumulated or 



3 C 2 applied, 



