X g Z Gen . Roy’s Account of 
the reft. In another place we (hall have occafion to point out, 
how the columns towards the right-hand of the fa id table have 
been filled up. 
i 
SECTION FIFTH. 
On the difference between horizontal angles on a fphere and 
fpheroid . Plate X. 
IN the Paper of 178 7, various computations were given 
concerning the figure and dimenfions of the earth, founded 
chiefly on the a6tual meafurement of different arcs of the 
meridian in different latitudes, fome of them very remote from 
each other. From the alternate comparifon of thefe refults it 
appeared, that the figure afligned to the earth by M. Bouguer 
in his fecond fpheroid agreed better with thefe meafured por- 
tions of the curve, as fo many data , than any of the other 
hypothefes . Hence it naturally occurred, that the trigonome- 
trical operation which we were then about to commence 
might probably throw fome further light on this intricate fub- 
je£l, which, for a great length of time, has engaged a confi- 
derable fhare of the attention of the fcientific world. In the 
confideration of this matter, a new and curious point, not for- 
merly attended to, and immediately connected with our ope- 
ration, prefented itfelf for inveftigation, viz . fuppofing the earth 
to be a fpheroid , fuch as M. Bouguer’s, confiderably flattened at 
the poles , what might be the difference between horizontal angles 
obferved with a fine inflrument on that fpheroid , and on a fphere ? 
The 
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