242 Professor Dean’s investigation of the apparent motion 
resenting an arch of a circle of declination. Make ZS = ZN =6° 39) 
the angle of inclination of the lunar orbit and equator, and ZE = ZW 
= 6° 18' the greatest equation of the moon’s centre. Draw also the 
circles of declination DEA, CWB, and the parallels of declination 
DNC, ASB. 
Preliminary Propositions. 
1. When the moon is in the ascending node both its poles are iu 
the circle of the disc, and the centre of the earth viewed by the spec- 
tator at the moon’s surface appears on the line EW, but declining 
south, as the south pole is entering the disc. 
2. When the moon has arrived at its greatest north latitude the 
centre of the earth, viewed as above, has arrived at its greatest south 
declination, and will be found in the line AB, 6° 39’ south of its mean 
place, and, like the sun in the tropics, will continue its declination 
some time nearly the same. 
- 3. When the moon is in the descending node, the earth again ap- 
pears on the line EW, but declining north as the north pole is enter- 
ing the disc. 
4, When the moon is at its greatest south latitude, the earth is at 
its greatest north declination or parallel CD, 6° 39’ north of its mean 
place, where it will continue some time nearly unaltered. 
5. When the moon is in its upper apsis, its true place coincides 
with its mean, and the earth, viewed as above, appears on the circle of 
declination SN, but its angular motion towards the east being slower 
than the moon’s motion on its axis, its apparent diurnal motion is to- 
wards the west. 
6. When the moon has arriyed at its mean distance, the earth, ob- 
served as above, is 6° 18’ behind or west of its mean place, and as the 
moon revolves on its axis with the mean uniform motion, the earth 
will appear just as far west of the circle of declination SN, in the line 
