1. Aries, [Zodiac: Aries] 2. Taurus, [Zodiac: Taurus] 3. Gemini, [Zodiac: Gemini] 4. Cancer, [Zodiac: Cancer] 5. Leo, [Zodiac: Leo] 6. Virgo, [Zodiac: Virgo] 7. Libra, [Zodiac: Libra] 8. Scorpio, [Zodiac: Scorpio] 9. Sagittarius, [Zodiac: Sagittarius] 10. Capricornus, [Zodiac: Capricornus] 11. Aquarius, [Zodiac: Aquarius] 12. Pisces. [Zodiac: Pisces] 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, one hundred degrees may be expressed either as the tenth degree of Cancer, or as 3s 10°. It will be found an advantage to repeat the signs in their proper order, until they are well fixed in the memory, and to be able to recognise each sign by its appropriate character. Of the various meridians, two are distinguished by the name of _colures_. The _equinoctial colure_ is the meridian which passes through the equinoctial points. From this meridian, right ascension and celestial longitude are reckoned, as longitude on the earth is reckoned from the meridian of Greenwich. The _solstitial colure_ is the meridian which passes through the solstitial points. The position of a celestial body is referred to the equator by its right ascension and declination. _Right ascension_ is the angular distance from the vernal equinox measured on the equator. If a star is situated _on_ the equator, then its right ascension is the number of degrees of the equator between the star and the vernal equinox. But if the star is north or south of the equator, then its right ascension is the number of degrees of the equator, intercepted between the vernal equinox and that secondary to the equator which passes through the star. _Declination_ is the distance of a body from the equator measured on a secondary to the latter. Therefore, right ascension and declination correspond to terrestrial longitude and latitude,--right ascension being reckoned from the equinoctial colure, in the same manner as longitude is reckoned from the meridian of Greenwich. On the other hand, celestial longitude and latitude are referred, not to the equator, but to the ecliptic. _Celestial longitude_ is the distance of a body from the vernal equinox measured on the ecliptic. _Celestial latitude_ is the distance from the ecliptic measured on a secondary to the latter. Or, more briefly, longitude is distance _on_ the ecliptic: latitude, distance _from_ the ecliptic. The _north polar distance_ of a star is the complement of its declination.