An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

14 THE EARTH.
35. The Solslitial Poidts are the two points of the ecliptic
most distant from the equator. The times when the sun comes
to them are called solstices. The summer solstice occurs about
the 22d of June, and the winter solstice about the 22d of
December.
The ecliptic is divided into twelve equal parts of 30~ each,
called signs, which, beginning at the vernal equinox, succeed
each other in the following order:
Northern. Southern.
1. Aries T 7. Libra -
2. Taurus 6 8. Scorpio fil
3. Gemnini It 9. Sagittarius T
4. Cancer - 10. Capricornus V3
5. Leo. 11. Aquarius -W
6. Virgo'l 12. Pisces X
The mode of reckoning on the ecliptic, is by signs, degrees,
minutes, and seconds. The sign is denoted either by its name
or its number. Thus 100~ may be expressed either as the 10th
degree of Cancer, or as 3s 10~.
36. Of the various meridians, two are distinguished by the
name of ColtrUes. The Euinoctial Colure is the meridian which
passes through the equinoctial points. The Solstitial Col2ure is
the meridian which passes through the solstitial points. As the
solstitial points are 90~ from the equinoctial points, so the solstitial colure is 90~ froin the equinoctial colure. It is also at
right angles, or a secondary to both the ecliptic and equator.
For, like every other meridian, it is of course perpendicular to
the equator, passing through its poles. Moreover, the equinox,
being a point both in the equator and in the ecliptic, is 90~
from the solstice, from the pole of the equator, and from the
pole of the ecliptic. Hence the solstitial colure, which passes
through the solstice and the pole of the equator, passes also
through the pole of the ecliptic, being the great circle of wllich
the equinox itself is the pole. Consequently the solstitial
colure is a secondary to both the equator and the ecliptic.
(See Arts. 19, 20, 21.)
37. The position of a celestial body is referred to the equator
by its right ascension and declination. (See Art. 27.) Right