S54 





APPENDIX. 



** The axis of the pendulum is of hard-tempered fte#l, 

 *' nearly two inches long, and moves on angular or knife- 

 *' pivots, whofe edges are formed with great care, fo as to 

 " lie exaOily in the fame right line ; the pivots are formed 

 *' nearly to an angle of thirty-eight degrees from the edge 

 ** to the back ; the fharpnefs of the edges is taken off, 

 and they are carefully rounded, fo that the lower parts 

 of both (on which the pendulum moves) form parts of 

 " one continued cylinder, whofe diameter is rather lefs 

 " than the two hundredth part of an inch. 



** Thofe Divots move in ansfular notches made in two 

 " pieces of hardened fteel, each a quarter of an inch thick ; 

 " the notches are formed to an angle of one hundred 

 " and twenty degrees, with their bottoms fomewhat 

 ** rounding, and formed fo that the whole length of the 

 *' pivot has an equal bearing in them ; the ends or extremi- 

 *' ties of the pivots are Hoped from the edges on which 

 ** they move, towards the backs, or upper fide; and 

 *' two plates of hardened fleel are fcrewed againft the 

 *' angular notches in which the pivots move, fo as to 

 " confine them always to the fame place in thie notches, 

 " and prevent fuch irregularities as might otherwife happen 

 " if the {houlders of the pivots fhould chance to touch. 



*' Towards one end of the axis is pierced an oblong 

 *' fquare hole, from the upper to the under fide, into 

 ** which Uj£ "pper end of the pendulum rod (having its 



'* fides 



