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fations are ufed, they fhould be executed with the fame materials 

 as that of the pendulum rod, and have exadly the fame expofure 

 to the air. 



A DESCRIPTION of a pcndulum, with a diamond fufpenfion. — 

 The lens is feven inches diameter, made of lead melted into a 

 brafs fhell, very accurately weighed in all pofitions, turned truly 

 in a very fteady lathe, firft flatwife, and then on an arbor 

 through its centre, and adjufted fo that in all fituations the 

 centre of gravity of the lens exadly coincides with the axis of 

 the pendulum rod ; a piece of brafs, half an inch thick and 

 three and an half long by two broad, is let into the lead fo as to 

 be even with its furface ; four holes being tapped in it to receive 

 the fcrews c c c c, Fig. II. with their heads counterfunk in the 

 brafs fhell : this piece of brafs is hollowed lengthwife on the 

 infide, fo as to embrace the pendulum rod, the whole length 

 of itfclf, but moft ftraightly at its centre. The lens never to be 

 altered after the clock is brought to time. The rod made of red 

 deal, firft baked, then boiled in linfeed oil for a confiderable 

 time, and then well varnifhed. On the top is formed an irregular 

 odagon and an opening cot through, of the fhape of the letter 

 U ; there is drilled in the lathe, exadly through its centre length- 

 wife, a hole to receive the piece of very hard caft fteel e, which 

 after being fitted fquare into a brafs collar f, paffes through the 

 hole in the upper part of the pendulum rod at 5, and is there 

 firmly fecured by a fcrew, the head of which is counterfunk 

 in the top of the rod ; at 6 the fteel piece is wrought to a fine 

 conical point, on which the whole pendulum is fufpended on the 

 well- levelled face of a large diamond ; this diamond is fet and 



C foldered 



