APPENDIX. 

 *' fides fomewhat flattened) is fitted, without fliake, but 

 " in filch manner that it moves freely therein from back 

 *' to front, round a fteel pin which pafles horizontally 

 " through it and the axis, that both the pivots may 

 " have an equal bearing, and the pendulum may hang 

 *' truely perpendicular, without any tendency to bend its 

 *' rod, and by that means alter its time of vibration, even 

 " though the axis be not accurately adjufied to a level 

 *' pofition : The error which might arife from accidental 

 ** fridion on the above fuppofition, of an inaccurate 

 " levelling of the axis, is obviated by means of the fteel 

 " plates againlt which the very central point of the lowell 

 " pivot mufl in fuch cafe adt. 



" To the other end of the axis, is fcrewed a pair of 

 " pallets, conftrudled nearly on Mr. Graham's- principle 

 " of the dead-beat, but differing from it in having a 

 *' degree of recoil which tends to render the longer vibra- 

 " tions of the pendulum as quick as the ILorter : but 

 " this precaution is the lefs neceflary, becaufe the weight 

 " which keeps the machine in motion is fo adjufted, as 

 " to make the angle of conftant vibrations as nearly as 

 " poflible the fame with the angle of fcapement ; that is, 

 " to make the vibrations the fliorteft, that will admit 

 " of the wheel to efcape tlie pallets : by this means, 

 " if the oil applied fliould become glutinous, fo as to 

 " diminifh the adion of the wheel on the pendulum, or 

 " if any other circumfiance fhould happen to fliorten the 



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