1o2 ESSAYS AND OBSERVATIONS: 
tion to one another, as the refpective di- 
{tances intercepted on the difk. 
3. HENCE, ¢ being the center of the 
circular portion, wce the ecliptic, if the 
femidiameter of the difk be exprefled by , 
the number of feconds in the arch ¢w or 
ce=horizontal parallax of the moon from 
the fun, every line drawn on the difk will | 
be exprefled by the feconds of its corre- 
fpondent arch of the moon’s {phere. 
4. Let C be the centre of the difk, 
WE,NS, the projections of we the eclip- 
tic, and #5 a circle of latitude; WNE 
being the upper or northern femicircle, 
and WS E the lower or fouthern. Let V 
be the place of any given vertex on the 
difk, and v the correfpondent point in the 
moon’s fphere; VA, VB, perpendiculars 
to NS, WE, and v 4,00 their correlatives. 
If the point v be the true place of the 
moon, i. ¢- if the vifible places of the fun 
and moon be the fame, then will VA be 
the par. lon. )#O, and VB. the par. lat. 
to a {pectator at the point V on the difk, 
or at the given vertex on the furface of 
the earth. For the par. loa. ) 4 @ asthe 
difference 
