Effect of Magnetism on Time-Pieces, Bfi 
No. 46. 
On the irregularity in the rate of going of Time-pieces 
occasioned by the infue\ je of Magnetism . An origi- 
nal Communication, by Mr . Varley, dated May 31, 
1798.* 
Haying studied tlie theory of clock and watch-making 
many years, as well as been, part of that time, concern- 
ed in an extensive manufactory of watches, I have had 
many opportunities of observing a circumstance which 
has surprised every one in the trade as well as myself f 
that watches of considerable price, and from the hands 
of excellent workmen, often perform no better than a 
plain one of inferior workmanship and much lower price. 
Being anxious, as may naturally be supposed, to furnish 
my friends with watches or clocks which would go well, 
I made it my business to pay particular attention to what- 
ever could contribute to their perfection. With this view, 
I made almost numberless experiments and observations 
on the various escapements now in use, the different con- 
structions of balances, pendulums, pendulum springs and 
compensations, both for clocks and watches, which have 
been applied by very ingenious mechanics and excellent 
workmen to correct the errors in the rate of going, espe- 
cially of watches, occasioned by the various degrees of 
heat and cold, change of position, external agitation, in- 
fluence of oil, friction, variation of maintaining power, 
and other causes. 
Some of these contrivances are extremely well adapt- 
ed to answer the intended purpose ; but, notwithstanding 
all their advantages, the maker and purchaser are fre- 
quently disappointed in the performance of the machine 
to which they are applied. Many instances might be 
♦ Tilloch, vol. I p. 16 . 
