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given in a rough way, yet they are of singular interest, as with them begins, at least for the western nations, the long train of observation and discovery that has brought the science to its present perfection +.

A striking proof of the acquirements of the Chaldæans is to be found in their knowledge of the period of 65854 days, in which the moon makes 223 revolutions with regard to the sun, 239 with regard to the apsides of her orbit, and 241 with regard to her nodes. This is attributed to them by Geminus : Ptolemy § refers it simply to the "ancient mathematicians." The accuracy of this period is very great, and its utility no less in calculating the recurrence of eclipses. Indeed, there can be little doubt that it was by means of this period, or one very analogous to it, that they were able to predict these phenomena in the case of the moon; for, according to Diodorus Siculus ||, they did not attempt such predictions for eclipses of the sun. This is natural enough; it is sufficiently obvious to those who have any acquaintance with the science, that the calculation of the former is far more easy, the parallax not entering into it. The author just quoted also tells us that they attached great importance to the theory of the planets, which bodies they observed with care, and more particularly Saturn. In fact we find in Ptolemy several such observations T. Their zodiac was divided into twelve signs**: the extra-zodiacal constellations were twenty-four in number, twelve in each hemisphere. To this we may add from Herodotus ++, that to them we owe the duodecimal division of the day. This historian attributes, at the same time,

V. Syntax., lib. iv. c. 5. The time is not given more nearly than within an hour-the quantity of the disk eclipsed is expressed in digits.

Ptolemy (Syntax. xiii. 7.), speaking of astronomical observations, informs us, that the most

numerous and best have been made in Chaldea. To this we may add a curious passage of Cleomedes, il. 6, who says, speaking of the moon being seen eclipsed, while the sun was above the horizon, that "so many eclipses of the moon having been observed and recorded, no astronomer, whether Chaldæan or Egyptian, has ever recorded one of

this kind."

+ Isagoge c. περὶ ἐξελιγμοῦ. Cf. Delambre, Astron. Ancienne, vol. i. p. 206, who disputes, upon rather inconclusive grounds, the claim of the Chaldæans to this period. Lib. iv. c. 2.

Lib. xi. c. 7, et alibi.

Lib. ii. c. 31.

to them the invention of the gnomon, and an instrument called polus. The former, we have already seen, was used in China from the earliest antiquity; of the last we have a very imperfect knowledge; it seems to have been destined to indicate the changes in the sun's meridian altitude towards the solstices. The divisions of time were measured by clepsydræ.

Seneca informs us that Epigenes and Apollonius Myndius, both of whom professed to have studied under the Chaldæans, ascribed to them very different opinions on the subject of comets. According to the former they were ignorant of their nature and course; while the latter, who is called by Seneca a most scientific observer of natural phenomena, states, that they classed them with the planets, and were able to determine their motions. It is certain that very philosophical ideas were entertained on the subject of comets by the Pythagoreans, who had evidently borrowed many of their doctrines from the East. Could we admit the statement of Apollonius, few things would tend more to give us a high idea of the Chaldæan astronomy.

CHAPTER IV.

The Egyptians.

THE Egyptians seem to have enjoyed in ancient times considerable reputation for astronomical science. It is, however, certain, that few, if any, relies of it have descended to us. It has been remarked, that the exactitude with which the Pyramids have been made to face the four cardinal points, gives us an advantageous idea of their methods of observation. However, Ptolemy and Hipparchus, who it is natural to suppose would have had access while living in the country to the Egyptian records, never quote any ancient observation made by astronomers of that nation; but, on the contrary, were forced to have recourse to the Chaldæans. On the other hand, there is some respectable testimony to prove that the Egyptians were in the habit of observing celestial phenomena in general, and eclipses in particular. Diodorus Siculus + goes so far as to say, that they were able to calculate beforehand the circumstances of

Each sign was subdivided into thirty degrees; these latter with much exactness. Dithe degree into sixty minutes.

tt Lib. ii. c. 109. What are we to say of Delambre, who assures us that no ancient author speaks of the gnomons of Chaldæa?-Astron. du Moyen Age, Discours Prélim., p. xi.

ogenes Laertius mentions 373 solar,

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and 832 lunar, eclipses observed in Egypt. The testimony of this author is in itself of no great weight, and he adds the absurd circumstance, that they had been seen in an interval of 48863 years. But it is very singular that this is the proportion of the solar to the lunar eclipses visible above a given horizon within a certain time*; and such a coincidence certainly cannot be accidental. Seneca likewise informs us, that Conon, the contemporary of Archimedes, had collected all the eclipses of the sun preserved in Egypt. Lastly, we may remark, that Aristotle & mentions the Babylonians and Egyptians as having recorded a great number of credible observations. To all this is to be opposed the silence of Ptolemy, and upon this point we must refer to the remarks already made when treating of the Chaldæan astronomy.

The civil year of the Egyptians was of 365 days, but they were very early acquainted with the more accurate value, 365 days. This appears from the Sothiac period of 1461 years, which brought round to the same seasons their months and festivals. For this people, among their numerous singularities, had that of not wishing to connect the civil invariably with the physical year, but to suffer it to anticipate gradually, displacing thereby all the times fixed for their religious ceremonies, till at the end of the great Sothiac period they coincided once more with their original positions. One of these periods, according to Censorinus §, began in the consulship of Antoninus and Bruttius, A.D. 139, That this was not the first period of the kind, there can be little doubt. The preceding one must have commenced, then, in the year 1322 B.C. Bailly even, relying upon some expressions of Manetho, thinks that this was preceded by another. But, as far as the tropical year is concerned, it is necessary to observe, that the Sothiac period could not have been deduced from an actual observation of the time required for a complete restitution, for the time observed would not have been 1461 years, but 1506. It has, however,

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been supposed that the Egyptians had a rural year, comprising the intervals between two heliacal risings of Sirius, and that the Sothiac period must be considered as applying to this rural, and not to the tropical year. And here we meet with a very curious coincidence; for this rural year, as thus determined, had, for twenty or thirty centuries before the Christian era, very exactly the length of 365 days; and, consequently, the period of restitution of 1461 years would apply to it very accurately. A recent author has disputed the fact, that such a rural year was in use among the Egyptians, before the time of Hip parchus: however, the authorities urged in its favour seem pretty satisfactory; and the coincidence above mentioned tends strongly to corroborate them. Thus it appears that the Sothiac or Canicular period had its origin when the first day of the month, Thoth, coincided with the heliacal rising of Sirius. According to Censorinus, this happened the 20th of July, A.D. 139. M. İdeler has found by calculation, that on the very same day of July, Sirius rose heliacally in the Julian years 1322 and 2782 B.C.

It

According to Dio Cassius, the Egyptians were the inventors of the short period of seven days, distinguished by the names of the planets, which we call week. This period, used among all the eastern nations from time immemorial, has been called, by an eminent philosopher, the most ancient monument of astronomical knowledge. is found even among the Brahmins of India with the same denominations, and the days similarly named by them and by us correspond to the same physical portions of time. The arrangement is founded upon the ancient systems of astronomy, in which the planets were placed in the following order, beginning with the most distant from the earth; Saturn, Jupiter, Mars, the Sun, Venus, Mercury, and the Moon. The day being divided into twenty-four hours, the hours were consecrated to the planets in the order just given; and each day took its name from the hour with which it began. Thus, the first hour of the first day being dedicated to Saturn, the second would be so to Jupiter, the third to Mars, and so on; then the eighth again to Saturn, the fifteenth, and the twenty-second, so that the first hour of

Biot, Essai sur la Période Caniculaire. + Lib. xxxvii. c. 18.

La Place, Syst. du Monde, lib. v. c. 1.

the second day would belong to the Sun. Proceeding in the same way, the first hour of the third day would belong to the Moon, of the fourth to Mars, &c. We have said, that in the ancient systems, Venus and Mercury were considered as inferior to the Sun; but upon this point there was some difference of opinion. The Egyptians seem to have perceived the real state of the case. They conceived these two planets to move round the sun, while they followed him in his annual revolution round the earth, and consequently were sometimes nearer than he to the earth, sometimes farther. This system, which is explained by several ancient authors, and among them obscurely by Cicero, more distinctly by Vitruvius, is positively attributed to the Egyptians by Macrobius. Some have been disposed to imagine that the constellations of the zodiac were originally invented in Egypt at a very remote period. This opinion has been advocated principally by Dupuis §, who conceives that the constellations in question had a reference to the divisions of the seasons, and to the agriculture of Egypt at the time of their invention. The sign of Cancer marks the retrogradation of the sun at the solstice; Libra, the equality of the nights and days at the equinox: the Capricorn, a climbing animal, is conceived to indicate the sun at its greatest height, or at the summer solstice; the autumnal equinox consequently falls in Aries. This system presents, certainly, some curious coincidences: thus, for example, the inundation of the Nile, which begins just after the summer solstice, would take place while the sun was in the constellations Aquarius and Pisces; and Virgo, usually represented as a woman with an ear of corn in her hand, would coincide with the time of harvest in Egypt. There is, however, one insuperable objection to this system, which is the excessive antiquity (not less than 15000 years) which it assigns to the zodiac. As this is historically inadmissible, Dupuis has modified his theory by supposing the names to have been given, not to the constellations in which the sun was, but to those diametrically opposed to him, which consequently were rising at sun-set at any given epoch. This opinion, which brings down the invention of these constellations to about 2500 years B.C., has been adopted by

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La Place and several distinguished philosophers*.

The scientific men who accompanied the French expedition to Egypt found in some of the temples of that country representations of the zodiac, which have given rise to much discussion in Europe. One of the most remarkable of these is on the ceiling of a portico in the temple of Denderah (the ancient Tentyra). It represents the signs of the zodiac in two rows, six in each, parallel to the axis of the temple, one to the right, the other to the left of the principal entrance; the latter all face, as if about to enter the temple, the former as if quitting it: the first of the entering signs is Aquarius, and the last Cancer: the Cancer, however, is thrown on one side out of the line, and its place filled by a head of Isis, partly plunged in the rays of the sun. It follows, from what has been said, that the first of the signs which appear to be coming out is the Lion, and the last Capricorn. Similar zodiacs are to be found in the porticoes of two temples at Esnè (Latopolis): but there the head of Isis is altogether wanting, and the bisection of the signs takes place between Virgo and Leo, instead of between Leo and Cancer. This bisection has been supposed by some to have a reference to the places of the solstices: but the supposition is entirely arbitrary, and would give to these temples an antiquity) which other circumstances by no means seem to support. Fourrier conjectures that the head of Isis, substituted in the place of Cancer, indicates that Sirius rose heliacally when the sun was in that constellation; which took place more than twenty centuries before the Christian

era.

M. Biot imagines that this indicates that Sirius rose with the stars of Cancer, near which the sun was at the time of the summer solstice, and refers the monument to about the year 700 B.C. There is in the interior of the temple at Denderah, another zodiac, sculptured on a ceiling, in which the signs are arranged in a circle, and here

Macrobius (Somn. Scip., lib. i. c. 21.) attributes the invention of the zodiac to the Egyptians; but against this it may be urged, that Sextus Empiricus, a writer of at least equal authority, ascribes it to the Chaldeans, lib. v.

This idea is deduced from the supposition that the constellation in which the sun was at the beginning of the year, was represented as the first in the line of the signs coming out of the temple, or appearing to lead the others: now the Egyptian rural year began at the summer solstice-thus the zodiac of Denderah would indicate that the summer solstice was in the Lion, those of Esne in the Virgin.

again the Cancer is thrown out of its proper line, its place being occupied by a mythological figure, below which is the symbol of Isis. M. Biot has attempted to prove that this circular zodiac is a planisphere representing the appearance of the heavens at midnight on the summer solstice, about seven centuries before the Christian era. But this opinion is exposed to many serious objections: these, however, the limits of this treatise will not allow us to enter into: we shall quit the subject with one observation. M. Champollion thinks he has decyphered among the hieroglyphics on the ceiling of the temple, the word abrogare, which would seem to indicate that the sculptures in question were as recent as the Roman empire. But this by no means precludes the possibility that they may represent a more ancient sphere. That the temple itself is not of great antiquity many circumstances seem to indicate; but the question to be solved is, whether the astronomical phenomena it depicts are, or are not, to be referred to some more distant epoch, which it was intended to record?

CHAPTER V.

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Origin of Astronomy in Greece.Thales.-The Ionian School. The Pythagoreans.-Meton-The Calendar.-Eudoxus.-Pytheas. THE astronomy of Greece undoubtedly begins with Thales and the philosophers of the Ionian School, about six centuries before the Christian era. Homer, indeed, and Hesiod, the only authors anterior to this period whose works we now possess, mention some of the most remarkable constellations, though none of those composing the signs of the zodiac ;t and the works of the latter author in particular show that some attention was paid in his time to the rising and setting of certain conspicuous stars. Thus he informs us that Arcturus rose heliacally sixty days after the winter solstice, from which we may deduce this poet to have lived about 950 B.C., unless,

Recherches sur l'Astronomie Egyptienne. Paris, 1823.

The constellations and stars mentioned by Homer, are the Bear, the Pleiades, the Hyades, Bootes, Orion, and Arcturus. Besides these Hesiod mentions Sirius. Neither make any mention of the planets, though Homer is supposed to allude to Venus in one passage-II. V. v.5; others think Sirius is meant. The planets in fact do not seem to have been astronomically observed in Greece till long afterwards. "Eudoxus," says Seneca, "quinque syderum cursus primus in Græciam ab Egypto transtulit." Quæst. Nat. vii, 3,

Op. et. Dies. v. 564.

indeed, which is not improbable, he copied some older calendar.* Herodotus † makes Homer and Hesiod contemporaries, and places them about 400 years before his own time, which would make them a century later than the date above assigned. But the whole question of their age is involved in much doubt and obscurity, nor is it important to the history of astronomy. We find little in these very ancient authors that throws light upon the interesting question, whether the Greek sphere was derived from that of the Egyptians, or other oriental nations. We shall see in the course of this treatise, that there can be no doubt that the zodiac was borrowed from Egypt or Chaldea, but the origin of the extra-zodiacal constellations is very uncertain. Seneca attributes the division of the heavens into constellations to the Greeks; and refers this division to fourteen or fifteen centuries before Christ. An obscure author, quoted by Clemens Alexandrinus,§ ascribes the invention of the sphere to Chiron, who may be referred to the thirteenth century B.C. That the Greek sphere, whether of native or foreign origin, is as old as the time assigned to Chiron, has been attempted to be proved by a passage from Eudoxus, quoted in the commentary of Hipparchus on Aratus. This author, who flourished in

the early part of the fourth century B.C. asserts, that there is a certain star in the celestial sphere, corresponding to the pole of the equator. Now this could not have been the polar star of our times, which was then, owing to the precession of the equinoxes, far from the pole; and upon examining that part of the heavens, there seems to be no other star that could be alluded to, except Draconis. About 1326 B.C. this star was within 4° of the pole, which was sufficiently near to make it appear immoveable to rude observers: and this fact has been thought to show that Eudoxus copied a sphere many centuries anterior to his own. This sphere has been supposed to be that of Chiron before alluded to; others attribute it to Musæus.¶ But not

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withstanding all that has been said upon this subject, it seems pretty evident, the positions of the stars given by Eudoxus are too discordant to admit of any conclusion being drawn from them*, and if Eudoxus copied any very ancient sphere, it must have been one of oriental origin; for in the time of Chiron (if indeed any such person ever existed) it is pretty certain that nothing was known in Greece about the existence of the ecliptic, the equinoxes, the colures, or any great circles of the sphere. The unanimous testimony of antiquity ascribes to Thales, or his immediate successors among the philosophers of the Ionian school, the invention of the zodiac, the discovery of the obliquity of the ecliptic, of the tropical revolution of the sun, and the principal circles of the celestial sphere. There is no reason for supposing that, before this time, the Greeks had advanced beyond remarking and naming a few of the most conspicuous constellations; and how little progress they had made in this, we may conjecture from the circumstance, that Thales first introduced into Greece the knowledge of the Little Beart, by which the Phoenician pilots used to steer, while the Greeks were contented with the rough approximation to the north given by the Great Bear. For it is very remarkable that Thales, if not, as some have pretended, a Phoenician, was certainly of Phoenician extraction; and this fact, corroborated by other authors, rests on the testimony of Herodotus himself. Many things seem to indicate that the science of Thales was of eastern origin, and that what have been called his discoveries, were doctrines borrowed from Chaldæa or Egypt. Much stress is not to be laid upon the account of his having studied in Egypt, which rests upon the equivocal authority of his biographer Diogenes, though this is confirmed by Clemens Alexandrinus§. But the extraordinary fact of his having predicted a solar eclipse, which can scarcely be dis

(V. Sophocles quoted by Achilles Tatius), and Atlas (V. Diod. Sic. lib. iii. Plin. ii. 8.)

V. Delambr. Astron. Anc. Introduct. p.11. and vol. i. p. 122.

† See Callimachus quoted by Diogenes Laertius in Thalete, and by Achilles Tatius, Cf. Hygin. Poetic. Astronom. V. Arctus. et Theon. in Arat. That the Little Bear was discovered by the Phoenicians, is attested by Strabo (lib. i. cap. 1), and the circumstance of their navigators sailing by it, is alluded to by many authors. V. Arat. Phonom. y. 39. Ovid. Heroid. xviii., et alibi.

V. Herodot., lib. i. c. 170, Cf. Diog. Laert, in Thalete. § Stromat. i. 14,

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puted, speaks volumes upon this subject. This we are told by Herodotus*, whose testimony seems above all suspicion, though he adds a singular circumstance, in which there is probably some mistake, that Thales assigned the limits of a year, within which this eclipse was to take place. It is unnecessary to remark, that could Thales have predicted an eclipse so remarkable as this, which was total in the country in which he lived-Asia Minor, he certainly must have been able to make a much nearer approximation. But as to the fact of the prediction there can be little doubt. The eclipse is memorable in ancient history, as having separated the armies of the Lydians and Medes, at that time engaged in battle; the historian lived not more than 150 years after the event in question, and was a countryman of Thales; but should his testimony be deemed insufficient, authority perhaps still higher may be quoted. Eudemus, an astronomer of eminence in the fourth century before Christ, composed a history of astronomical discoveries, now unfortunately lost; but Diogenes Laertius and Clemens Alexandrinus both quote the authority of Eudemus for this prediction of Thales: and in farther corroboration of this, Eudemus, in a fragment preserved by Anatolius§, attributes the discovery of solar eclipses to Thales. Indeed it may be said that there is no point on which the testimony of antiquity is more decided and unvarying, than that Thales introduced into Greece the prediction of solar eclipses ||, and most probably at the same time the explanation of their real cause. Pliny indeed does not quite agree with Eudemus as to the date of this eclipse, which has been a subject of controversy among ancient and modern authors; but the knowledge of the exact year in which it happened is more interesting to chronologists than astronomers**.

⚫ Lib. i.c. 74.

+ Thales was a native of Miletus-Herodotus of Halicarnassus, both towns on the coast of Asia Minor.

V. Diog. Laert. in Thal. Clem. Alex. Stromat. lib. i. c. 14. § V. Fabric. Bibliothec. Græc., lib. iii. c. ii. Vol. ii. p. 215. Hamburgh, 1797.

Besides the authors above quoted, V. Achilles Tat. Isagog. Plin. Hist. Nat. ii. 12. Cicero de Divinatione i.

This is expressly attributed to him by Plutarch de Placit. Philosoph. ii. 24.

On this point the reader is referred to aninteresting paper by Mr. Bailly, in the Philosophical Transactions for 1811, where all the opinions on the subject are discussed. Mr. Bailly himself refers the eclipse to the year 610 B.C.

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