60 PHILOSOPHICAL TRANSACTIONS. [anNO 1684. 



will keep the circular body more steady in its present position. And the same 

 principle which hitherto has been the cause of its rest, will become the cause of 

 its motion. For let the numbers 1,2, 3, 4, in fig. 6, represent a train of wheel- 

 work, wherein there is no material difference from what is found in a common 

 watch; only the numbers of the teeth on the wheels and pinions are to be so 

 calculated, that the motion of the whole train may correspond to the assigned 

 revolution of the body of the movement, which is to be once in 24 hours. It 

 would be expedient also, that a spiral spring be applied to its balance, as is usual 

 in the latter movement; but there is no need of a fuse; for the turns of the 

 body of the movement, as it descends on the stage, answer all the purposes of 

 a string or chain; and the contranitence of the weight P to the excess of LED 

 above LQD, serves instead of a perpetual spring; and the movement w^nts 

 only a perpetual descent, to make its motion so. And as the great wheel, in 

 ordinary movements, is placed as near the edge of the framing plate ff, as it 

 can be; in this case it must, with its axis or arbor M, possess the centre of the 

 movement : because this wheel is to carry the weight or power P by the lever 

 MP, and that weight P must always keep equidistant from the centre of the 

 movement, that while the body of the movement performs its revolutions, the 

 said weight P, and the great wheel, to which it is fixed, may, without any con- 

 siderable variation, continue in or near the present position. Now suppose this 

 weight P, with its lever MP, to be taken quite out of the movement, and then 

 conceive the body of the movement to be placed on a horizontal plain HH, its 

 point of contact in that plain is T, where it should, but cannot rest ; because 

 the weight of that part of the train marked with the numbers 2, 3, 4, removes 

 the centre of gravity from M ; and therefore on the opposite part of the move- 

 ment, as about CQ, the inside of the hoop, which forms the case, is to be 

 loaded with a thin lining of lead, which may be a counterpoise to that part of 

 the train; that so the whole body of the movement, excepting only that P with 

 its lever is now laid aside, may rest on that horizontal plane, or while it rides 

 upon its own axis, indifferently in any point. This reducing of the movement 

 to an equilibration of all its parts in the centre M, must be performed by trials, 

 i. e. by rasping the lead at CQ, as much and in such places as is needful; which 

 to an artificer of ordinary sagacity, will not be at all difficult. 



The centre of gravity being thus reduced to M, the next thing is to replace 

 the weight P, which, by the hole H, fig. 7, is to be set on the arbor of the 

 central wheel M. Now let the body of the movement be placed on the declivity 

 DE; and supposing P-|-LQD = LDE; then the body must needs rest there: 

 but because the weight P is not now, as in fig. 5, fixed to any part of the quad- 



