» ASTRONOMICAL AnD 
ridians, but is fometimes more, and fometimes lefs, according 
to the parallaxes. Thefe, therefore, muft be carefully comput- 
ed ; and the tedioufnefs of the procefs has, doubtlefs, prevent- 
ed obfervations of this kind from becoming fo generally ufe- 
ful, as they would otherwife have been. Bat, as the difficulty 
may appear leffened, by having the whole operation breught 
into one view, I now take the liberty of doing it, for the fake 
of thofe who have not made great advances in aftronomy, fhould 
any fuch meet with this paper. I have taken, for examples, 
thofe obfervations which have led to a determination of the 
difference of meridians between London and Cambridge, and 
Paris and Cambridge. An accurate determination of this dif- 
ference may be very ufeful. Hereby, the aftronomic tables, 
which have been fitted to the meridians of the celebrated ob- 
fervatories of Paris and Greenwich, are made our own, for all 
the purpofes of calculation ; and our cea oa be made 
ufe of, for corre&ting ar roving the ould 
new ones be oe for Cittibridpe dic fime ‘may | be: ac— 
commodated to E Europae obíervatories, " 
PROBLEM) ~ bie a 
Given the moon’s longitude, latitude, horizontal parallax 
and horizontal femi-diameter, together with the altitude of the. 
nonagefimal degree of the ecliptic, and the angle of it’s pole, 
or angle PpZ, and confequently the longitude of the nonagefi- 
mal degree, to find her parallax m latitude and longitude, her 
vifible femi-diameter, or femi-diameter augmented agreeably to. 
her altitude ‘or zenith diftance, and the vifible m of 
TTG Eo the fun and moon ie: 
IP - 
