THE 



PHILOSOPHICAL MAGAZINE. 



I. On Deal Fendulum Rods. By Mr. E. Walker. 



To Mr. Tilloch, — Sir, 

 /AS my paper, containing a short abstract of the rates of 

 going of clocks with wooden penduhim rods, may appear to 

 some of your readers a cominuniiation of loo little impor- 

 tance to obtain a jjlace in the Philosophical Magazine, it 

 may not be improper to observe, that it is only from such 

 registers we can judge how much one time-keeper is prefer- 

 able to another. For, who would believe, without having 

 recourse to facts, that clocks with deal pendulum rods per- 

 form nearly as well as the transit clock at the Royal Obser- 

 vatory ? 



The performance of my clock shows some properties in 

 pendulums with deal rods, which differ from those composed 

 of rods of different metals, to counteract the effects of head 

 and cold. — It evidently appears from my former paper* : 



P'irst, That this clock lost of true time at one season of the 

 year and gained at another. 



Secondly, That twice every year it went true time : and, 



'i'hirdly. That those variations took place regularly durinsj 

 eight years. 



The same paper also shows, that there is very little diffe- 

 rence in the rates of the four pendulums, although they were 

 made by different artists at different times, and consequently 

 that they were made out of different pieces of wood. 



When the performance of my clock is compared with 

 that of the celebrated astronomical clock at Greenwich with 

 a gridiron pendulum, made by Mr. John Sliclton, under the 



* Pliilnsophical Magazine, vol xxxili. p. 30. 



Vol. 31. No. 133. July 1800. A '2 direction 



