[381] 
is, very near its centre) was, in order to keep the object glafs 
at the fame height ; though this being lefs than an inch in 
diameter, and confequently fubtending lefs than 13" from the 
top of the hill, there could not have been a fecond of time dif- 
ference, whether the ftars had been obferved to vanifh behind 
the hill, either in the upper or lower part of the field of 
view. 
Mr. Short alfo remarks, that no inference can be formed with 
refpeft to the different forces of gravity, in different latitudes, 
from experiments made with clocks, becaufe the fame clock, fet 
up on different fides of the fame room, will be found to differ 
con fide rably from ltfelf. I readily allow that, if clocks are fixed 
up in a flight manner, or againft common wainfcots, the expe- 
riments made with them cannot be depended upon. Neverthe- 
lefs it does not appear, but that when they are fixed in a fiimei 
manner, they may be depended upon near enough to be of a 
coniiderable ufe in phyfical enquiries : which I have reafon to 
think from the many experiments I have tried with the Royal 
Society’s clock, made by Mr. John Shelton, which I propofe to 
give a particular account of at fome other opoitunity. 
Obfervations of the Sun’s fetting in the Sea.. 
At the Obfervatoty at the Alarum-Houfe, which, by careful 
menfuration, I found to be elevated 1983 feet above the. level 
of the fea. Therefore the height of the eye is 1988 feet. 
1761 
June 14 
June 16 
July 18 
July 30 
App 1 Time 
H / // 
5 39 5^ 
5- 39- 1 : 
I 5 39 34 
I. 5 42 8 
5 44 21 : 
O ’s upper limb fet in the fea. 
O’s upper limb fet. A little cloudy. 
O ’s L. L. fet in the fea, certain to 2 or 3 S. 
O ’s U. L. fet in the fea, certain to k S. 
O’s U. L, fet in the lea. A little cloudy. 
The 
