His geography was based more immediately on the work of his predecessor, Marinus of Tyre, and on that of Hipparchus, the follower and critic of Eratosthenes.
By a former marriage he already had two sons, Hippias and Hipparchus, now growing up, and in his first tyranny or his first exile he married an Argive, Timonassa, by whom he had two other sons Iophon and Hegesistratus, the latter of whom is said to be identical with Thessalus (Ath.
He was succeeded by his sons Hippias and Hipparchus, by whom the tyranny was in various ways brought into disrepute.
List of ostracized persons, the first of whom was a certain Hipparchus of the Peisistratid family (488 B.C.).
It is an extraordinary fact that, if ostracism was introduced in 598 B.C. for the purpose of expelling Hipparchus it was not till twenty years later that he was condemned.
The following is a list of persons who suffered ostracism: - Hipparchus (488); Megacles (487), Xanthippus (485), Aristides (483), Themistocles (471?); Cimon (461?) Thucydides, son of Melesias (444), Damon, Hyperbolus (417) and possibly Cleisthenes himself (q.v.).
The problem of determining an orbit may be regarded as coeval with Hipparchus, who, it is supposed, found the moving positions of the apogee and perigee of the moon's orbit.
The city is supposed to have been surrounded by a wall before the time of Solon, the existence of which may be deduced from Thucydides' account of the assassination of Hipparchus (vi.
Hipparchus, the famous astronomer, on the other hand, (c. 150 B.C.) proved a somewhat captious critic. He justly objected to the arbitrary network of the map of Eratosthenes.
A few latitudes had indeed been observed, but although Hipparchus had shown how longitudes could be determined by the observation of eclipses, this method was in reality not available for want of trustworthy time-keepers.
Hipparchus is not known to have compiled a map himself.
The celestial globe of Hipparchus still existed in the Alexandrian library in the time of Ptolemy, who himself refers to globes in his Almagest, as also in the Geography.
The credit of having returned to the scientific principles innovated by Eratosthenes and Hipparchus is due to Marinus of Tyre (c. A.D.
Ptolemy's great merit consists in having accepted the views of Hipparchus with respect to a projection suited for a map of the world.
Following Hipparchus he divided the equator into 360 drawing his prime meridian through the Fortunate Islands (Canaries).
The cylindrical and modified conical projections of Marinus and Ptolemy were still widely used, the stereographical projection of Hipparchus, was for the first time employed for terrestrial maps in the 16th century, but new projections were introduced in addition to these.
This era is famous in astronomy, having been generally followed by Hipparchus and Ptolemy.
The founder of the mathematical school was the celebrated Euclid (Eucleides); among its scholars were Archimedes; Apollonius of Perga, author of a treatise on Conic Sections; Eratosthenes, to whom we owe the first measurement of the earth; and Hipparchus, the founder of the epicyclical theory of the heavens, afterwards called the Ptolemaic system, from its most famous expositor, Claudius Ptolemaeus.
Gradually, from Eratosthenes to Tycho, Hipparchus playing the most important part among ancient astronomers, the complex astrolabe was evolved, large specimens being among the chief observa tory instruments of the 15th, 16th and even 17th centuries; while small ones were in use among travellers and learned men, not only for astronomical, but for astrological and topographical purposes.
It combines the planisphere and armillae of Hipparchus and others, and the theodolite of Theon, and was usually of brass, varying in diameter from a couple of inches to a foot or more.
The constellations bearing the same names coincided approximately in position, when Hipparchus observed them at Rhodes, with the divisions they designate.
The earlier Greek writers - Eudoxus, Eratosthenes, Hipparchus - knew of only eleven zodiacal symbols, but made one do double duty, extending the Scorpion across the seventh and eighth divisions.
The representation thus handed down (in the verses of Aratus) has been thought to tally best with the state of the sky about 2000 B.C.; 12 and the mention of a polestar, for which Eudoxus was rebuked by Hipparchus, seems, as W.
For nowhere could he have had a better means of consulting the works of historians, geographers and astronomers, such as Eratosthenes, Posidonius, Hipparchus and Apollodorus.
He had before him the results of Eratosthenes, Hipparchus and Posidonius.
He accepted also the division into five zones; he quotes approvingly the assertion of Hipparchus that it was impossible to make real advances in geography without astronomical observations for determining latitudes and longitudes.
Hipparchus reckoned the twenty-four hours from midnight to midnight.
Sosigenes Could Scarcely Fail To Know That This Year Was Too Long; For It Had Been Shown Long Before, By The Observations Of Hipparchus, That The Excess Of 3654 Days Above A True Solar Year Would Amount To A Day In 300 Years.
This procedure - which was first employed by the great Greek astronomer Hipparchus (2nd century B.C.), and developed by Ptolemy three centuries later - did not afford any law connecting the motions of different bodies.
We know that Peisistratus ruled by controlling the archonship, which was always held by members of his family, and the archonship of Isagoras was clearly an important party victory; we know further the names of three important men who held the office between Cleisthenes' reform and the Persian War (Hipparchus, Themistocles, Aristides) from which we infer that the office was still the prize of party competition.
Several works have been attributed to him, but they are all lost; some fragments are preserved in the extant TWV 'Apa-rov Kai EiMEov cbacvo thvwv E07ryilvEwv (30Xia Tpia of the astronomer Hipparchus (ed.
The Platonic dialogue Hipparchus attributes it to Hipparchus, son of Peisistratus.
Again, the Platonic dialogue Hip parchus (which though not genuine is probably earlier than the Alexandrian times) asserts that Hipparchus, son of Peisistratus, first brought the poems to Athens, and obliged the rhapsodists at the Panathenaea to follow the order of the text, " as they still do," instead of reciting portions chosen at will.
Such attempts usually start with the tacit assumption that each of the persons concerned - Lycurgus, Solon, Peisistratus, Hipparchus - must have done something for the text of Homer, or for the regulation of the rhapsodists.
It is true that Hipparchus is undoubtedly a real person.
Thucydides notices as a popular mistake the belief that Hipparchus was the eldest son of Peisistratus, and that consequently he was the reigning " tyrant " when he was killed by Aristogiton.
The Platonic Hipparchus follows this erroneous version, and may therefore be regarded as representing (at best) mere local tradition.
Only that Homer was recited in fragments by the rhapsodists, and that these partial recitations were made into a continuous whole by Peisistratus; which does not necessarily mean more than that Peisistratus did what other authorities ascribe to Solon and Hipparchus, viz.
The author of the Hipparchus is evidently influenced by the anti-democratical tendencies in which he only followed Plato.
It may even be suspected that anecdotes in praise of Peisistratus and Hipparchus were a delicate form of flattery addressed to the reigning Ptolemy.
Distrusting tradition, he took a few of the finest dialogues as his standard, and from internal evidence denounced as spurious not only those which are generally admitted to be so (Epinomis, Minos, Theages, Arastae, Clitophon, Hipparchus, Eryxias, Letters and Definitions), but also the Meno, Euthydemus, Charmides, Lysis, Laches, First and Second Alcibiades, Hippias Major and Minor, Ion, Euthyphro, Apology, Crito, and even (against Aristotle's explicit assertion) The Laws.
Kugler 7 that the various periods underlying their lunar predictions were identical with those heretofore believed to have been independently arrived at by Hipparchus, who accordingly must be held to have borrowed from Chaldaea the lengths of the synodic, sidereal, anomalistic and draconitic months.
Hipparchus and Ptolemy entertained the same large organic designs; they worked on similar methods; and as the outcome, their performances fitted so accurately together that between them they re-made celestial science.
The choice made by Hipparchus of the geocentric theory of the universe decided the future of Greek astronomy.
An interval of 250 years elapsed before the constructive labours of Hipparchus obtained completion at Alexandria.
Professor Newcomb, who has compiled an instructive table of the equinoxes severally observed by Hipparchus and Ptolemy, with their errors deduced from Leverrier's solar tables, finds palpable evidence that the discrepancies between the two series were artificially reconciled on the basis of a year 6 m too long, adopted by Ptolemy on trust from his predecessor.
In the hands of Hipparchus the theory was brought to a degree of precision which is really marvellous when we compare it either with other branches of physical science in that age or with the views of contemporary non-scientific writers.
The discoveries of Hipparchus were :- I.
This Hipparchus was enabled to do by lunar eclipses.
Therefore the eccentricity found by Hipparchus was only 5°, and was more than a degree less than its true value.
He found that, although the two inequalities found by Hipparchus and Ptolemy correctly represented the moon's longitude near conjunction and opposition, and also at the quadratures, it left a large outstanding error at the octants, that is when the moon was 45° or 135° on either side of the sun.
We may conclude the ancient history of the lunar theory by saying that the only real progress from Hipparchus to Newton consisted in the more exact determination of the mean motions of the moon, its perigee and its line of nodes, and in the discovery of three inequalities, the representation of which required geometrical constructions increasing in complexity with every step.
To the Greek astronomer Hipparchus belongs the credit of the discovery (c. 130 B.C.) of the theory of the precession of the equinoxes, for a knowledge of which among the Babylonians we find no definite proof; but such a signal advance in pure science did not prevent the Greeks from developing in a most elaborate manner the theory of the influence of the planets upon the fate of the individual.
The original is lost, but a versification by Aratus (c. 270 B.C.), a poet at the court of Antigonus Gonatas, king of Macedonia, and an 'E rrynves or commentary by Hipparchus, are extant.
In this enumeration Serpens is included in Serpentarius and Lupus in Centaurus; these two constellations were separated by Hipparchus and, later, by Ptolemy.
On the other hand, Aratus kept the Pleiades distinct from Taurus, but Hipparchus reduced these stars to an asterism.
Aratus was no astronomer, while Hipparchus was; and from the fact that the latter adopted, with but trifling exceptions, the constellation system portrayed by Aratus, it may be concluded that the system was already familiar in Greek thought.
And three hundred years after Hipparchus, the Alexandrian astronomer Ptolemy adopted a very similar scheme in his uranometria, which appears in the seventh and eighth books of his Almagest, the catalogue being styled the "EKOfois Kavovud7 or " accepted version."
The Ptolemaic catalogue embraces only those stars which were visible at Rhodes in the time of Hipparchus (c. 150 B.C.), the results being corrected for precession " by increasing the longitudes by 2° 40', and leaving the latitudes undisturbed " (Francis Baily, Mem.
The names and orientation of the constellations therein adopted are, with but few exceptions, identical with those used at the present day; and as it cannot be doubted that Ptolemy made only very few modifications in the system of Hipparchus, the names were adopted at least three centuries before the Almagest was compiled.
Eratosthenes (276-196 B.C.) used most probably a solstitial armilla for measuring the obliquity of the ecliptic. Hipparchus (160-125 B.C.) probably used an armillary sphere of four rings.