first gradually displaced astrology for the ben-years B. C. The Chaldean investigations of efit of true scientific knowledge.-Astrology the motions of the moon were in many respects was early developed in Egypt, but chiefly remarkable. In particular their invention of flourished in Chaldea, whose "star-gazers and the saros indicates not merely very accurate monthly prognosticators" were so famous that observation and a careful discussion of the rethe name Chaldee came to be used as identical sults, but considerable ingenuity. They were with astrologer, not only in the Scriptures, but also acquainted with the art of dialling; they also by the classical writers. In the East it still had discovered the precession of the equinoxes, has its votaries. It was much practised in im- and had determined the length of the tropical perial Rome. It was forbidden by Augustus, year to within less than half a minute of its and the edict was often reenacted by later em- true value. There are even reasons for believperors, but was apparently not much regarded. ing that they were acquainted with the true The Arabs revived astrology with astronomy. system of the universe; and we learn from The Moors in Spain held it in great respect, Diodorus Siculus and Apollonius Myndius that and by their influence it was made popular the Chaldean astronomers regarded comets as among the Gothic nations of western Europe. bodies travelling in extended orbits, and even The astronomical tables of Alfonso X. in the in some instances predicted the return of these 13th century were in great part intended for objects. Indian astronomy does not appear to astrological purposes. Astrology continued to have been by any means so accurate as that increase in credit till the middle of the 16th taught by the Chaldeans. The Indian system century, was still practised at European courts seems indeed to have belonged to a more at the end of the 17th, and had a few votaries northerly latitude than Benares, the chief seat till the end of the 18th, even in England. It of Hindoo learning. Accordingly M. Bailly was in high repute at the court of Catharine was led to ascribe the origin of the system to a de' Medici; it was considered a science even nation which had inhabited higher latitudes; by Kepler; and Lilly, the last of the famous as- and he even went so far as to invent a nation trologers, was called before a committee of the for the occasion, the Atlantides, and to ascribe house of commons in the reign of Charles II. to that apocryphal nation a wholly incredible to give his opinion of future events.-The gen- degree of learning. It may be inferred that the eral method of procedure in finding the fate of want of agreement between celestial phenomany man or enterprise was to draw a horo- ena in India and the Indian system of astronscope, representing the position of the stars omy, instead of justifying M. Bailly's argument, and planets, either in the whole heaven, or shows rather that the Indian astronomers within one degree above the eastern horizon, were but imperfectly acquainted with the pheat the time of birth of the individual or the in- nomena of the heavens. Nor is it easy to acception of the undertaking. Arbitrary signifi- cept the opinion of Prof. Smyth, astronomer cations were given to different heavenly bodies, royal for Scotland, that the ancient Egyptians, as they appeared singly or in conjunction; and the architects of the great pyramid, were acaccording to these significations, the horoscope quainted with all the facts which he conceives was interpreted. The presence of Venus fore- to have been symbolized in that remarkable told love; Mars, war; Jupiter, power; the edifice. That the pyramid was erected for Pleiades, storms at sea, &c. The system of a astronomical purposes may be admitted; and reputable astrologer in the 16th century re- we may accept Prof. Smyth's conclusion that quired years for its mastery; and absurd as its the building of the pyramid corresponded to fundamental principles now appear, its details the time when the star a Draconis at its upper were not inconsistent with each other, and the transit was visible (as well by day as by night) whole system has a completeness which ap- through the long inclined passage which forms pears very singular in a scheme so visionary. one of the characteristic features of the pyramid. This would set the epoch about the year 2170 B. C. And it is a remarkable fact that, as Prof. Smyth points out, the Pleiades were at that time in a most peculiar position, well worthy of being monumentally commemorated; "for they were actually at the commencing point of all right ascensions, or at the very beginning of running that great round of stellar chronological mensuration which takes 25,868 years to return into itself again, and has been called elsewhere, for reasons derived from far other studies than anything hitherto connected with the great pyramid, the 'great year of the Pleiades.'" But although we may thus set the astronomical system of the early Egyptians in a far antiquity, it seems unsafe to follow Smyth in believing that the builders of the great pyramid were acquainted with ASTRONOMY (Gr. åσrpov, a star, and vóuoç, law), the science which deals with the movements, distribution, and physical characteristics of the heavenly bodies. That astronomy is the most ancient of all the sciences, save agriculture, can scarcely be questioned. In the earliest ages men must have required measures of time, and such measures could only be obtained from the study of the motions and appearances of the celestial bodies. The origin of astronomy has been referred to several nations. The evidence in favor of the Chaldeans seems on the whole the strongest. We find in Ptolemy's Almagest the records of observations of considerable accuracy made at Babylon at a very early epoch. Some of the observations which were transmitted to Aristotle by Callisthenes were made about 2250 the sun's distance, with the true length of the precessional period, and with other astronomical elements the discovery of which has rewarded the exact methods and the profound mathematical researches of modern times.-As to Chinese astronomy, we have abundant evidence to show that it was inexact, though undoubtedly very ancient. Its antiquity may be inferred from the circumstance that the emperor Chwen-hio adopted as an epoch a conjunction of the planets Mercury, Mars, Jupiter, and Saturn, which has been shown by M. Bailly to have occurred no less than 2449 years B. C. In a remarkable work on the subject of Chinese astronomy, recently published by Mr. Williams, assistant secretary of the astronomical society of England, we are told that the instruments at present used by Chinese astronomers, as well as their principal methods of calculation, were introduced by Jesuit missionaries. Yet the ancient Chinese must have possessed some familiarity with the celestial motions. They could calculate eclipses; for we learn that "in the reign of the emperor Chow-kang, the chief astronomers Ho and Hi were condemned to death for failing to announce a solar eclipse which took place 2169 B. C.; " a clear proof that the prediction of eclipses was a part of the duty of the imperial astronomers. The Chinese were also acquainted with the Metonic and Callippic cycles.-The earliest Greek school of astronomy was that founded by Thales of Miletus (600 B. C.) and termed the Ionian school. Thales appears to have been acquainted with the motions of the sun and moon, with the explanation of seasonal changes, and with the length of the year. It has been said that he taught mariners to regard the Lesser Bear rather than the Greater as the polar constellation; but Manilius ascribes the selection of the Lesser Bear as the cynosure to the Phonicians. To Pythagoras, who also belonged to the Ionian school, a knowledge of the true theory of the earth has been ascribed, though on insufficient grounds. According to the statement of his pupil Philolaus, he taught that "the earth and planets move in oblique circles (or ellipses) about fire, as the sun and moon do" a statement which certainly does not as it stands indicate exact knowledge respecting the constitution of the solar system. Nicetas of Syracuse is said in like manner to have taught that the diurnal motions of the celestial bodies are caused by the rotation of the earth upon her axis. 66 Theophrastus," says Cicero, "narrates that Nicetas of Syracuse held that the sun, moon, and stars are at rest, and the earth alone moves, turning about its axis, by which the same phenomena are produced as if the contrary were the case." Eudoxus of Cnidus first endeavored to explain the looped paths of the planets, solving the problem by the invention of the theory of concentric spheres.-But it was by the Alexandrian school, founded under the Ptolemies, that exact and systematic observation of the celestial bodies was first undertaken. Hipparchus of Nicea (160 B. C.) surpassed all the astronomers of antiquity in skill and acumen. He made the first catalogue of the stars, and was the first to calculate the motions of the sun and moon. He also made a series of observations of the planets, and represented their motions by the famous theory of epicycles-a theory which, though unsound, was in so far in advance of previous ideas, that it was intended to be brought into comparison with the real motions of the celestial bodies. Hipparchus also invented plane and spherical trigonometry. Ptolemy is another distinguished member of the Alexandrian school. Some of the theories and observations which have been ascribed to him were indeed due to the labors of Hipparchus. Thus the Ptolemaic system of astronomy was wholly based on the theories of his predecessor; and the star places indicated in his works seem to have been simply deduced from Hipparchus's catalogue of 1,081 stars by introducing a correction for precession. Yet Ptolemy's labors were unquestionably important. He detected the inequality in the moon's motions called the evection, and was the first to recognize the effect of refraction in altering the apparent places of the heavenly bodies. His work, the Almagest (or the Syntaxis), contains nearly all that we know of the astronomy of the ancients. The school of Alexandria ceased to exist when Egypt was invaded and conquered by the Mohammedans, and the celebrated Alexandrian library destroyed, in the 7th century. The Arabians, however, formed no contemptible astronomers. They even surpassed the Greeks in the department of practical astronomy; and they handed down to the Europeans the system which they had derived from their predecessors. In the 13th century European astronomy may be said to have had its origin or revival, though nearly two centuries elapsed before any important advance was effected. Toward the close of the 15th century the labors of Purbach and Regiomontanus prepared the way for the work of Copernicus, the founder of the true system of astronomy; while Waltherus revived the art of astronomical observation, and thus indirectly supplied the means of establishing the theories of Copernicus, Kepler, and Newton. Copernicus (born in 1473) found that by placing the sun instead of the earth at the centre of the scheme, there resulted a simple and rational explanation of all the chief motions of the planets. He was not able to show, however, that the epicycles of Hipparchus and Ptolemy could be wholly removed. Accordingly, many astronomers, who might have been attracted to the Copernican system if it could have been presented as it is known in our day, were found in the ranks of its opponents. Among these was Tycho Brahe, the Dane, who pointed out that the apparent fixity of the stars is opposed to the Copernican theory, unless the distances of all the stars be assumed to exceed enormously the distance of the earth from the sun. He therefore adopted a modifi- tained by Picard. We know in fact that Newcation of a system once held by the Egyptians, ton was led by erroneous ideas of the earth's regarding the earth as the centre around which dimensions to abandon the theory of gravitathe sun revolves, while the planets revolve tion for nearly 20 years. Returning to his rearound the sun as a subordinate centre. Al- searches in 1680, when news of Picard's results though this was a retrogression, astronomy had reached him, Newton was able to establish owes a debt of gratitude to Tycho Brahe for the theory of gravitation on a firm and stable the observations by which he endeavored to basis. He showed that the moon is drawn to put the Copernican theory to the test. His the earth by terrestrial gravity, diminished at observations of Mars, in particular, enabled the moon's distance in the same degree that Kepler to remove for ever from astronomy the the square of that distance exceeds the discycles and epicycles, centrics and eccentrics of tance of points on the earth's surface from the the old systems. Endeavoring to explain the earth's centre. He proved that when the force motions of Mars on the Copernican theory, of attraction diminishes according to the law Kepler found himself baffled so long as he ad- of the inverse square, the attracted body will hered to circular and uniform motions so com- obey all the laws of Kepler in its motions bined as to produce epicyclic paths. He was around the attracting orb. Then he extended thus led to try whether the ellipse would bet- his inquiries to the mutual perturbations of ter explain the movements of Mars. After bodies so moving. Taking the moon as an inlong and patient study he was able in 1609 to stance of the effects of perturbation, he showed establish his first two laws, and nine years later how several peculiarities in her motions which his third law. The three laws are as follows: had hitherto seemed inexplicable are caused by 1. Every planet describes an ellipse about the the sun's perturbing action on the moon, that sun, this orb occupying one focus of each such is, by the excess or defect of his action on the ellipse. 2. If a line be supposed continually moon in different parts of her orbit, as comdrawn from the sun to any given planet, this pared with his action on the earth. Pursuing line will sweep over equal areas in equal times. his researches, he showed how the precession 3. The squares of the periodic times of the of the equinoxes can be accounted for by the planets are proportional to the cubes of their law of gravitation; he formed and discussed inean distances. In the mean time the telescope two theories of the tides; he solved the probhad been invented, and when less than one lem presented by the oblateness of the earth's year had passed after the publication of the figure. Half a century passed before any atfirst two laws of Kepler, Galileo had made a tempts were made to extend the reasoning of series of observations tending to illustrate if the Principia, or to develop the views of its not even to demonstrate the truth of the Co- author. During this half century British pernican system. In particular his discovery mathematicians were chiefly engaged in deof the satellites of Jupiter, and the recognition fending, continental mathematicians in attackof the motions of these orbs around their pri- ing, the principle of universal gravitation. mary, was felt even by the enemies of the new But in 1745 Euler and Clairaut began to aptheory to be strikingly in its favor. Here was ply the new methods of mathematical anala system in which the motions of the earth ysis to the problems discussed by Newton. and planets around the sun seemed pictured in Clairaut succeeded in explaining the lunar miniature. The discovery of the phases of Ve- evection, which had foiled Newton; and this nus was also regarded as a serious blow to the success encouraged continental astronomers to Ptolemaic system. The invention of the tele- devote their powers to the investigation of the scope supplied also the means of determining problems presented by the celestial motions. the places and therefore the motions of the They mastered one after another the difficulties celestial bodies with a degree of accuracy of the lunar and planetary perturbations. The which had hitherto been unattainable. He- analytical researches of Lagrange and Laplace, velius indeed endeavored to make a stand and in particular the discovery (independently against the innovation, adhering until the end made by both) of the great laws on which the of his career to the methods used by the an- stability of the planetary system depends, are cients. But gradually the telescope prevailed, only inferior to the discovery of the law of and the way was thus prepared for the re- gravitation itself in interest and importance. searches of Newton, whose discovery of the It would be difficult to say which of these two law of gravitation would never have been ad- geometers displayed the greater powers of mitted but for the evidence in its favor attained analytical research. If the genius of Lagrange by means of telescopic observations. In par- was the more profound, yet Laplace's labors ticular, the measurement of the earth's dimen- led to more important practical results, and in sions with the requisite accuracy could not discovering the real interpretation of the "long have been accomplished without telescopic ob- inequality" of Jupiter and Saturn he mastered a servations of star places; and Newton would problem which had foiled his great rival. Yet have been unable to show that the moon is re- another noble achievement of Laplace's must tained in her orbit by the same force which be mentioned his interpretation of the secudraws objects to the earth's surface, had not lar acceleration of the moon's mean motion. accurate measurements of the earth been ob- In recent times it has been shown indeed by Adams that Laplace's investigation of the sub- of the fact that multitudes of meteoric sysject was imperfect; yet undoubtedly he placed tems exist within the confines of the solar his finger on the true cause of that part of the domain, and that the component members of acceleration which is due to the ordinary forms these systems must be counted by millions. of perturbation, nor has the cause of the re- The recent observations of Profs. Newton and maining part of the moon's acceleration been Kirkwood in the United States, Prof. Alexhitherto ascertained. Finally, we may regard ander Herschel and Mr. Glaisher in England, the publication of his Mécanique céleste as form- Quetelet in Belgium, Schmidt in Athens, Heis ing a veritable epoch in the history of physical in Germany, and Secchi in Rome, have added astronomy. Passing over many important con- largely to our knowledge respecting meteors; tributions to the theory of gravitation, we may while the mathematical researches of Schiapapoint to the achievement of Adams and Lever- relli, Adams, Leverrier, and others, have rerier in the discovery of the planet Neptune as vealed the interesting fact that these bodies perhaps the most conclusive of the evidences are intimately associated with comets.-The yet adduced in support of Newton's theory. telescopic study of the starry depths, though it A planet hitherto unseen was made known to has been prosecuted laboriously by the Herus, not as in the case of Uranus by a happy schels, Struve, Argelander, Mädler, and others, chance, but by a study of the deviations of a must be regarded as still (owing to the vastness known planet from the path calculated for it of the domain to be explored) in its infancy. by mathematicians. It may be added that the The elder Herschel first conceived the daring discovery of Neptune led to the recognition idea of gauging the celestial depths; but as a of the mastery which American astronomers matter of fact the regions surveyed by the and mathematicians had obtained over the two Herschels amount to but a minute portion more recondite departments of analysis. It has of the heavens. On the other hand, though been remarked by Prof. Grant of Glasgow Argelander's survey extended over a complete that "the results which have been deduced hemisphere, yet the telescopic power employed from Bond's observations of the satellite of was but small. Dr. Gould, an American astronNeptune, and the mathematical researches of omer, is extending Argelander's system of surWalker and Peirce, unquestionably exhibit a vey to the southern heavens; and the result candegree of consistency with the actual observa- not fail to be of the utmost interest and value. tions of Uranus and Neptune which has not been We owe to the Herschels nearly all our present paralleled by any similar efforts in Europe; knowledge of the strange objects called nebulæ while at the same time they tend to throw or star cloudlets. Of these only 16 were known much interesting light on the theory of both in Halley's time, and barely 200 when Sir W. planets." Among the more recent contribu- Herschel began his telescopic labors. He and tions to the mathematics of astronomy must be his son added between them nearly 5,000 nebmentioned Adams's discussion of the moon's ulæ to the list of known objects of this class. secular acceleration and the researches to At present some 5,700 nebulæ are known in which that discussion led, Delaunay's exten- all. The theoretical considerations by which sion of the lunar theory, and the inquiries of the Herschels have endeavored to interpret the Prof. Newcomb into the same subject.- scheme of the universe are too important to While mathematical astronomy had been thus pass unnoticed in this brief sketch of the hisadvancing, observational astronomy made sim-tory of astronomy. They have presented the ilar progress. The discovery of Saturn's ring and largest satellite by Huyghens was soon followed by the discovery of four other satellites. Later Sir W. Herschel discovered two other Saturnian satellites, while in comparatively recent times Bond in America and Lassell in England discovered an eighth. Uranus was added to the planetary system by Sir W. Herschel in 1781, and at sundry times four Uranian satellites have since been discovered, while four others are by some supposed to have been seen by Sir W. Herschel. Neptune and his satellite constitute two other known members of the planetary scheme. But to these must be added 130 small planets (see ASTEROIDS) which travel between the paths of Mars and Jupiter; while the observations and researches of Bond and Peirce in America and Maxwell in England tend to show that the rings of Saturn are composed of multitudinous small satellites. Apart from these discoveries, the complexity of the scheme ruled over by the sun has been indicated by the discovery galaxy to our contemplation as a scheme of suns, many equalling and many surpassing our own sun in magnitude and splendor, while they have taught that many of the star cloudlets are schemes of suns resembling the galaxy in extent and constitution. If some, as Whewell, Herbert Spencer, and others, do not regard these views as demonstrated or even demonstrable, yet we cannot but contemplate with admiration the activity of mind which enabled the Herschels, after completing unrivalled series of observational researches, to propound theories so magnificent respecting the myriads of orbs which they had examined.-The spectroscopic analysis of the sun and other celestial bodies, in the hands of Kirchhoff, Huggins, Young, Secchi, Zöllner, Lockyer, and Respighi, has revealed many facts of importance. It has been shown that in the sun many of our familiar elements exist in the form of vapor. In the planetary atmospheres known vapors, and especially the vapor of water, have been detected. The stars have been proved to be oria Motus Corporum Calestium, translated by Admiral C. H. Davis, U. S. N. (Boston, 1858), Delambre's Astronomie, or Peirce's "Analytical Mechanics" and "Celestial Mechanics." For the history of astronomy, see Whewell's "History of the Inductive Sciences," Grant's "History of Physical Astronomy," Jahn's Geschichte der Astronomie, and Delambre's Histoire de l'astronomie. For full information concerning the modern history of astronomy, Zach's Monatliche Correspondenz, Lindenau's Zeitschrift, Schumacher's Astronomische Nachrichten, continued by Dr. Peterson, and Gould's "Astronomical Journal" (Boston) must be consulted; also, the French Connaissances des temps, which contain Leverrier's discussions that led to the discovery of Neptune, the Berlin Jahrbuch, the Milan Effemeridi, and the American "Ephemeris and Nautical Almanac." ASTRUC, Jean, a French physician, born at Sauve, March 19, 1684, died May 5, 1766. He was a graduate and became a professor of the medical college of Montpellier as a substitute of Chirac, on whose death he succeeded him in the professorship, after having filled for some time the chair of anatomy in Toulouse. In 1730 he became regent and professor of the faculty of medicine at Paris, and was also phy suns, many closely resembling our sun in elementary constitution, others formed very differently, but all incandescent orbs as he is, and surrounded by the glowing, vapors of many elementary substances. The application of the analysis to nebulæ has led to the surprising discovery that while many of these objects shine with a light resembling that of our own sun, so that they may be considered to be formed by the aggregation together of many stars, others consist almost wholly of glowing gas, nitrogen and hydrogen forming their chief constituent elements. The observations of recent solar eclipses have been rewarded by many interesting discoveries respecting the physical constitution of the sun, the colored prominences surrounding him, and the corona which lies beyond the prominences. In these discoveries, Huggins, Young, Janssen, Lockyer, Respighi, and Secchi have borne the principal part. The progress of practical astronomy, and particularly the application of the telescope to the determination of the exact position of the celestial bodies, has proceeded pari passu with the progress of mathematical analysis and direct telescopic observation. The invention of the equatorial, the transit instrument, the mural circle, and other instruments of exact observation, belongs to the comparatively early his-sician to the king. His most celebrated work tory of modern astronomy. In the present day these instruments are constructed with a degree of perfection, and with a multiplicity of contrivances for improving their performance or extending their application, which are truly surprising. Nor have the achievements of instrumental astronomy fallen short of the promise afforded by the qualities of the instruments. It would be sufficient to point out that the telescope has revealed the greater number of those minute inequalities of planetary motion which have afforded the material for the analytical researches above referred to; but we may add that we owe to the telescope the recognition of the aberration of light, the discovery of the proper motions of the stars, the determination of the sun's distance, and the partial solution of the most difficult problem yet attacked by astronomers, the determination of the distances of the stars. Lastly, the spectroscope promises to play an important part in instrumental researches, since already it has been applied to the determination of the velocity with which stars are approaching us or receding from us, and to the measurement of movements taking place within the solar atmospheric envelopes. For a popular view of astronomy, Sir John Herschel's "Outlines" may be recommended; and full details respecting practical astronomy will be found in the treatise on that subject by Prof. Loomis of New York, justly described by Prof. Nichol as "the best work of the kind in the English language." A thorough knowledge of physical astronomy would require an acquaintance with such works as Laplace's Mécanique céleste, translated by Bowditch, Gauss's The VOL. II.-4 is De Morbis Venereis Libri sex (2d ed., 2 vols., 1740; translated into French and other languages); and he was regarded as a high authority on venereal and female diseases and obstetrics, though he excelled rather by his prodigious memory than by inventive genius. Among his many other writings are Traité des maladies des femmes (6 vols., 1761-5), and a posthumous work, L'art d'accoucher réduit à ses principes (1 vol., 1768). ASTURIAS, a former province of N. W. Spain, bordering on the bay of Biscay, bearing the title of principality, and still commonly known by its ancient name, although since 1833 it constitutes the province of Oviedo; area, 4,088 sq. m.; pop. in 1867, 588,031. The surface is irregular and hilly, the country being intersected by offshoots of the Cantabrian mountains, a chain varying in height from 6,000 to 10,000 feet. The scenery is picturesque and wild, and the coast is almost everywhere bold and high. The rivers are few and generally unimportant, the Nalon being the chief. The province is rich in coal, and in the north many mines are worked; the coal is shipped from Aviles and Gijon. Maize, wheat, potatoes, and fruits are the chief productions. The horses of Asturias are celebrated for strength and endurance. The inhabitants are of simple habits, retaining many old Spanish customs and peculiarities of dress that have elsewhere disappeared. They are proud of the freedom of their race from the admixture of Jewish and Arab blood found in the other provinces, and affect a superiority to other Spaniards. The herdsmen (vaqueros) among them form a separate and nomadic class, spending the winter on the coast and the sum |