( ;o 6 ) 
Second and an half flower in 14 Hours, -than when 
its own Weight of 1 ilk. io?0.s. was hung on. 
This Experiment (hews, that a fmall Difference in 
the Arcs defcribed by the Pendulum, or a fmall Al- 
teration in the Weight that keeps it in Motion, will 
caufe no great Difference in the Duration of the Vi- 
brations-, and therefore a little Alteration in the Te- 
nacity of the Oil upon the Pivots, or in the Foulnefs 
of the Clock, will not caufe it to accelerate, or retard 
its Motion fenfibly ; from whence we may conclude, 
that whatever Difference there fhall appear to be, be- 
tween the going of the Clock at London and in Ja- 
maica, it mud wholly proceed from the lengthening 
of the Pendulum by Heat, and the Diminution of 
the Force of Gravity upon it. 
A particular written Account of the Obfervations 
and Experiments hitherto taken Notice of, was deli- 
vered to me by Mr. Graham in September, 1731 ; 
about the fame Time the Clock was put on Ship- 
board to be carried to Jamaica. He likewife fent 
very full Direftions to Mr. Campbell , defcribing in 
what manner the 'dock was to be fixed up, and how 
the Pendulum might be reduced exaftly to the fame 
State as it was when in England ; but no Intimation 
was given concerning the going of the Clock, that the 
Experiment might be made with all poflible Care, 
and Caution, and without any Byafs, or Prejudice, 
in favour of any Hypothefis, or former Obferva- 
tions. 
In July 1731, we received an Account of the 
Succefs of the Experiment, by the Hands of Mr. 
Jcfeph Harris, who was prefent at the making of 
it in Jamaica , whither he went the Year before 
with 
