( 5 0Z ) 
having burn’d it with Soap in the manner defcrib’d. 
It is no Treafure ; but if you have none of it, it may 
be worth your Acceptance. 
I am, Sir, 
Utrecht , Jan. Your, &c. &c. 
ifth, 1733.O.S. Petrus Fan Mufcbenbroek. 
VI I r. An Account of fome ObferVations ?nade in 
London, by Mr. George Graham, F. S. and 
at Black- River in Jamaica, byCoVm Camp- 
bell, Efq^ F. p. S. concerning the Going of a 
Clock 3 in order to determine the Difference be- 
tween the Lengths of lfochronal Pendulums in 
thofe Places. Communicated by J. Bradley, 
M. A. Ajlr. Prof. SaVill. Oxon. F. P. S. 
A Ltho' it is now above Sixty Years fince Mr. 
Richer firft difcovered, that Pendulums of the 
fame Length, do not perform their Vibrations in 
equal Times in different Latitudes ; and tho* feveral 
Experiments made fince in different parts of the 
Earth concur to prove,- that Pendulums fwinging 
Seconds are in general fhorter as we approach the 
Equator; yet what the real Difference is between 
their Lengths in different Latitudes, does not feem 
to have been determined with fufficient Exadnefs, 
by 
