364 ■W''?"' Efiopemeni. — PiJIctis enilr-ely MetaUli:. 



the centre of motion of the lever, one part \ and from the centre of motion to the centre oF 

 the fri£lion-wheel, when the bahmce is at reft, two parts : fo that, whatever the velocitjr 

 may be at the end of the pallets when in motion, that part of the lever, or the forked part of 

 U, which is oppofite the centre of motion of the fridlion-whecl, will be twice as much. 



S S reprefents a fuperficial view of the pallets. The pallet below the pillar-plate is taken 

 ofFfrom the other, otherwife the place of aflion could not be feen in the drawing. 



In Jig. I, we have a view of the lever before the machine is wound up : a pin is half-«'ay 

 down the pallet ; but when the pin impels the pallet, the lever moves, and gives motion to 

 the balance, and the pin is difengaged from the pallet at the angle : that inllant a pin, on 

 the oppofite fide of the wheel, falls upon a circular part of the end of the other pallet, or 

 upon that part where it and the lever are entirely at reft, until the balance makes its return, 

 r.nd the friftion-wheel comes into the forked end of the lever. Then the friftion-wheel 

 Impels the lever, while the balance runs over the fpace of about one hundred degrees. 

 Tlien the pin drops off at the end of the pallets as before, and the balance is entirely kft at 

 liberty ; at which time its velocity is lb great, and its motion fo eafy, that it turns once round 

 upon its pivots, and two hundred and forty degrees every vibration. 



It is to be obfcrved, that, in the ends of the fork, one part is turned up and the other down, 

 in order they may not both go through one notch in the balance arbor j for, by having two 

 different parts cut away, the fork is locked faft in every vibration, and is unlocked only by 

 the fri£lion-wheel in its return for another vibration. 



Notwithftanding the balance makes one turn and two hundred and forty degrees every 

 vibration around its axis, yet, when the balance is at reft, and the fame power applied to 

 it (which keeps it in motion as above), the balance will only move through the fpace of 

 about fifteen degrees, which is only one fortieth part It keeps it up to when in motion. 



It muft be allowed, the lefs the wheels, or the power, have to do with the balance, the 

 more accurate the time will be fliewn *, 



XI. 



On Mr. CARTWSIGHr's Inveniwii for rendering the Pijlons of Steam Engines, Pumps, and 

 ether Hydraulic apparatus tight by metallic Parts, ivithoiit packing or leathering. (W. N.) 



To Mr. NICHOLSON. 



SIR, Richmond, Oft. 10. 175S. 



I 



HAVE lately been informed, that a new method of packing fteam engines has been in- 

 vented by a Mr. Cartwright, which is faid to be particularly advantageous in faving fri£lion 

 and refifting an heavy column of water in pumps. I (hall be very glad to fee a defcription 

 of the fame in your Journal, with your opinion of its effe£ls, &c. 



Your conftant Reader, 



A.R. 



* Artifts will perceive that this is an improvement of the anchor fcapementof Mudge,ofwhich the inventor 

 was not aware till he came to London. In this the pallets cxaftly refemble thofe of Graham's dead beat (Philof. 

 Journal, II. 51. ), and a tail afts againft two planes in the axis of the balance. Pallets like thofe of Mr. Prior 

 were adapted to a long pendulum by Mr. Crofthwaite of Dublin, in the year J7SS, (Memoirs of the Irifh 

 Acad, vol, II.) and fince that time alfoby other perfons in Lohdon, N. 



THE 



