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LXX XVI. Obfervations for proving the Go- 
ing of Mr. EllicottV Clock, at St. Helena ; 
by Air. Charles Mafon. 
Read May 6, Y ]\t m y return from the cape of Good 
j[ Hope, the clock, ufed in the obferva- 
tions made there, was fet going at James’s fort, St. 
Helena, the pendulum remaining as at the Cape. 
Here I found myfelf at a great lofs, to get obferva- 
tions to prove its motion, the heavens being almoft 
perpetually covered with clouds. At length, confi- 
dering, that the place being iituated in fuch a narrow 
deep valley, if the times of the defcent of the ftars, 
over the weftern ridge of rocks, (the altitude of 
whofe neareft fummit was about 30°, and diftant about 
a quarter of a mile, at the obfervatory) were ob- 
ferved, it would give the time per clock, in a fidereal 
day; and the chances for fuch obfervations would be 
greater, than by any other method, as they might be 
continued the whole night. Accordingly, I began 
to oblerve, by fixing the eye to a point : but this was 
loon improved, by the Reverend Mr. Mafkelyne, by 
making the ftars defcend each night, in the fame 
part of the telefcope of the equal altitude inftrument : 
and it was very beautiful to lee, how indantaneoully 
they difappeared. 
The difference of the effect of gravity at the two 
places, on the going of the clock, may be feen, by 
comparing the following with the obfervations made 
at the Cape. 
1761. 
