The azure dome, called the firmament in the book of Genesis, was believed to be a solid transparency, which we find described, in the fourth chapter and sixth verse, of that collection of Astronomical Allegories, called the Apocalypse, or Book of Revelation, "as a sea of glass like unto crystal." It was represented as being supported by four pillars, resting upon the earth, one at each of the cardinal points, which were designated as "the pillars of heaven." Conceiving the idea that there were windows in the firmament, the ancient Astronomers called them "the windows of heaven" and taught that they were opened when it rained, and closed when it ceased to rain. Hence it is evident that the ancient Astronomers did not refer to these pillars and windows in a figurative sense, but as real appurtenances to a solid firmament, as will be seen by reference to Gen. vii. 11, and viii. 2, Job xxvi. 11, and Malachi iii. 10. The Planets. Believing that the stars were but mere flambeaux, suspended beneath the firmament, and revolving round the earth, for the sole purpose of giving it light and heat; and observing that seven of these, answering to the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn, had perceptible movements, in relation to the other luminaries, the ancient astronomers designated them as planets or wandering stars. The Constellations. Perceiving that the other celestial luminaries maintained the same relation to each other, and designating them as fixed stars, the ancient astronomers grouped those visible to them into forty-eight Constellations; and giving names to these, they also attached names to the stars of larger magnitude, which was done for the purpose of locating and distinguishing them with greater ease. The Zodiac.