A Boar Hunt To face page 682 Quagga, with a View of the Table Mountain, at the Cape of Good Hope VOLUME VI. 688 Major Mony's perilous situation on falling into the Sea with First and Second Pyramids of Gizah, Ancient Memphis, and 485 489 494 496 498 Interior of the Temple of Apollinopolis Magna, at Edfu ib. Cromlech and Cheese-wring, at Layon, Cornwall 572 The Eddystone Light-House 589 THE GALLERY OF NATURE AND ART. PART I. NATURE. BOOK I. ASTRONOMY. CHAPTER I. ASTRONOMY OF THE ANCIENTS BEFORE THE FOUNDATION OF THE ALEXANDRIAN SCHOOL. A CONTEM CONTEMPLATION of the Heavens must at all times have fixed the attention of mankind; and especially in those happy climates where the serenity of the atmosphere invited them to observe the Stars. Agriculture required that the seasons should be distinguished and their returns known. It could not be long before it was discovered that the rising and setting of the stars, when they plunge themselves in the Sun's rays, or when they again disengage themselves from his light, might answer this purpose. Hence we find, that among most nations this species of observations may be This chapter, extracted from La Place, is given as nearly as may be from the translation of our own Astronomer Royal; but the numerous and unaccountable errors of this translation have compelled us to a perpetual collation with the original, and to alterations in every page.-Editor. VOL. I. B GAL.of NAT.& ART. Jan. 1, 1813. traced back to such early times, till their origin is lost. But some rude remarks on the rising and setting of the stars could not constitute a science. Astronomy did not commence till observations being registered and compared, and the celestial motions examined with greater care, some attempt was made to explain their motions and their laws. The motion of the sun in an orbit inclined to the equator; the motion of the moon, its phases and eclipses; a knowledge of the planets and their revolutions, and of the sphericity of the earth, were probably the objects of this ancient astronomy, but the few monuments of it that remain are insufficient to ascertain either its epoch or its extent. We can only judge of its great antiquity, by the astronomical periods which it has transmitted to us, by some just notions which the Egyptians and Chaldeans seem to have had of the system of the world, and by the exact relation of the ancient measures to the circumference of the earth. Such has been the vicissitude of human affairs, that that of the arts which could alone transmit the events of past ages in a durable manner, being of modern invention, the remembrance of the first inventors has been entirely effaced. Great nations, whose names are hardly known in history, have disappeared from the soil which they inhabited; their anuals, their language, and even their cities have been obliterated, and nothing is left of their science or their industry, but a confused tradition, and some scattered ruins, of doubtful and uncertain origin. It appears that the practical astronomy of these early ages, was confined to the observations of eclipses, the rising and setting of the principal stars, with their occultations by the moon and planets. The path of the sun was followed by means of the stars which were eclipsed by the twilights, and perhaps by the variations in the meridian shadow of the gnomon. The motion of the planets was determined by the stars which they came nearest to in their course. To distinguish these bodies, and recognize their various motions, the heaven was divided into constellations. And that zone from which the sun, moon, and planets, were never seen to deviate, was called the zodiac. It was divided into the twelve following constellations: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, and Pisces. These were called Signs, because they served to distinguish the seasons. Thus the en trance of the sun into Aries, in the time of Hipparchus, marked the commencement of the spring, after which it described the other signs, Taurus, Gemini, &c. but the retrograde motions of the equinoxes, changed the coincidence of the seasons; nevertheless, observers accustomed to mark the commencement of the spring by the entrance of the sun into the sign Aries, have continued to characterise this season in the same manner, and have distinguished the signs of the zodiac from the constellations, the first being ideal, and serving only to designate the course of the sun in the ecliptic. Now, however, that we endeavour to refer our ideas to the most simple expressions, we begin no longer to use the signs of the zodiac, but mark the positions of the heavenly bodies on the ecliptic, according to their distance from the equinoctial point. Some of the names given to the constellations of the zodiac, ap. pear to relate to the motion of the sun. Cancer, for example, seems to indicate the retrogradation of this body from the solstice, and Libra, or the Balance, denotes the equality of day and night. And other names seem to refer to the climate and agriculture of those nations to whom the zodiac owes its origin. The most ancient observations that have been transmitted to us with sufficient detail, are three eclipses of the moon, observed at Babylon in the years 719 and 720 before the Christian æra. Ptolemy, who cites them in his Almagest, employs them in his determination of the motion of the moon. It is certain, that neither he nor Hipparchus could obtain any that were more ancient, for the exactness of the comparison is in proportion to the interval which separates the extreme observations. This consideration should diminish our regret for the loss of nineteen hundred years of observations by the Chaldeans, and of which they boasted in the time of Alexander, and which Aristotle obtained by means of Calysthenes. But they could only have discovered the period of 6,585 days, by a long series of observations. This period, called the saros, has the advantage of bringing back the moon to nearly the same period, with respect to its node, its perigee, and to the sun. Thus, the eclipses observed in one period, afford an easy method of calculating those which are to happen in the succeeding ones. The lunar-solar period of six hundred years, seems to have been known to the Chaldeaus. These two periods suppose a knowledge nearly approximating to the true length of the year; it is also highly probable, that they |