JOURNAL 



OF 



NATURAL PHILOSOPHY, CHEMISTRY, 



AND 



THE ARTS. 



MAY, 1805. 



ARTICLE L 



f^eUer from Mr, Thomas Re id, on the Conjiruciion of Time* 

 keeping Machines, 



To Mr. NICHOLSON. 

 SIR, 



In your interefting and ufeful Journal of December laft, I Compenfatlon 



was glad to fee the improvement of compenfation pendulums m". Edvvard 



for aftronomic^l clocks, fo zealoufly taken up by fuch an able Troughton. 



band, as that of Mr. Edward Troughton's. 



But an excellent clock of this fort becomes fo very valuable 



and necefTary an appendage in an obfervatory, to Ihofe aftrono- 



niical inftruments with which he is fo happily engaged in daily 



conftrufting and improving; that he muft more readily fee 



their advantage than even thofe whofe bufinefs it is to make 



fuch clocks. If Mr. Bertht)ud, a celebraled author on every Probability from 



part that reirards the improvement of time-keepinsc machines. Serthoud's ex- 

 . ^ . ,, , ini- periments that 



IS correct, it would appear, that the ileel wires of Mr. the fteel wires 



Troughtoii's pendulum muft be too flender. Mr. Berthoud, ""'=*>' ^^ '®® ^'S^^ 

 by his experiments, favv, that there was a certain ftrength of 

 materials neceflary, in order lo render the compenfation com- 

 plete having found, that on the pendulum rods (if too fmall) 

 being lengthened by heat, the contraf^ion by cold would not 

 Vol. XL— Mav, 1805. B bring 



