t 465 ] 
A P P END I X. 
A Supplement to Major-General Roy’s Account of the Mode pro - 
pofed to pe followed in determining the relative Situation of the 
Royal Obfervatories of Greenwich and Paris. See p. 188. 
Read Nov. 8, 1787. 
I N the account of the propofed trigonometrical opera- 
tion for determining the difference between the meri- 
dians of the Royal Obfervatories of Greenwich and Paris, 
I have, at p. 221. and 222. had occafion to remark on an 
inconfidency found in the fum of the three equations, as 
Rated by M. Bouguer, for obtaining the lengths of de- 
grees of great circles perpendicular to the meridian, above 
their correlponding degrees of latitude, without having been 
aware of the true fource of the error, for which I am in- 
debted to the inveftigations of the Aftronomer Royal ; who, 
having found it out, obligingly communicated the fame to 
me, about the time of the annual recefs of the Society in 
the end of June lad. 
At p. 289. and again at p. 313. and 314. of M. Bou- 
guer’s Book, the fubtraclive branch of the equation, or the 
part of DG the gravicentric arc, anfwering to the difference 
between the radii of curvature at the equator and given lati- 
tude, has erroneoufly been expreffed in words fths inftead of 
.fths, which the algebraic formula juftly gives for it, and ac- 
. cording to which M. Bouguer’s table has been accurately 
computed. Not fufpedting any thing of this fort, no intima- 
T t t 2 tion 
