C 479 ] 
LXXXI. A Defcription of Two Methods , by 
which the Irregularity of the Motion of a 
Clock y arifng from the Influence of Heat 
and Cold upon the Rod of the Pe?idulum , ?nay 
be prevetited \ by John Ellicott, F. R. S . 
Read June 4, r g \ H E firfl: of thefe methods confifts in 
1/52 JL a particular conftrudtion of the pen- 
dulum itfelf, which occurr’d to me feveral years ago. 
In the beginning of the year 1738, I put into the 
hands of Mr. Machin, then one of the fecretaries, a 
defcription and a drawing of fuch a pendulum, in 
order to their being laid before this honourable 
Society : but Mr. Machin, foon after, acquainting 
me, that a gentleman, of whofe fkill and judgment 
in mechanical contrivances I had always entertain’d 
the higheft opinion, made fome objections, I was 
advifed to defer communicating my invention to this 
Society, till I fhould have examined into the weight 
of thofe objections, and, by a fair and impartial 
trial, fhould be fully allured, that the contrivance 
would anfwer the end propofed. And having now 
at length obtain’d that fatisfaCtion, I beg leave to 
give a fhort narrative of fome of the mod remarka- 
ble obfervations I have made during this inquiry, 
which I hope will not prove unacceptable to this 
honourable Society. 
About the year 1732, an experiment, which I 
made, in order to fatisfy fome gentlemen , that the 
..rod of a pendulum was liable to be conliderably in- 
fluenced by moderate degrees of heat and cold, led 
me 
