PTOLEMY. 



stars now extant, and forms the most va- 

 luable part of Ptolemy's works. He then 

 treats of the galaxy, or milky- way ; also 

 of the planevary aspects, with the rising 

 and setting of the sun, moon, and stars. 



In the ninth book he treats of the or- 

 der of the sun, moon, and planets, with 

 the periodical revolutions of the five 

 planets ; then he gives tables of the 

 mean motions, beginning with the theory 

 of Mercury, and showing its various phe- 

 nomena with respect to the earth. 



The tenth book begins with the theory 

 of the planet Venus, treating of its great- 

 est distance from the sun ; of its epicycle, 

 eccentricity, and periodical motions ; it 

 then treats" of the same particulars in the 

 planet Mars. 



The eleventh book treats of the same 

 circumstances in the theory of the pla- 

 nets Jupiter and Saturn. It also corrects 

 all the planetary motions, from observa- 

 tions made from the time of Nabonazar 

 to his own. 



The twelfth book treats of the retro- 

 gressive motion of the several planets, 

 giving a]so tables of their stations, and of 

 the greatest distances of Venus and Mer- 

 cury from the sun. 



The thirteenth book treats of the se- 

 veral hypotheses of the latitude of the 

 five planets ; ci liic greatest latitude or 

 inclination of the orbits of the five pla- 

 nets, which are computed and dis;;csecl 

 in tables ; of the rising and setting of the 

 planets, with tables of them. Then fol- 

 lows a conclusion or winding-up of the 

 whole work. 



This great work of Ptolemy will al- 

 ways be valuable, on account of the ob- 

 servations he gives of the places of the 

 stars and planets in former times, and 

 according to ancient philosophers and as- 

 tronomers, that were then extant ; but 

 principally on account of the large and 

 curious catalogue of the stars, which be- 

 ing compared with their places at pre- 

 sent, we thence deduce the true quantity 

 of their slow progressive motion, accord- 

 ing to the order of the signs, or of the 

 precession of the equinoxes. 



Another great and important work of 

 Ptolemy was, his Geography, in seven 

 books ; in which, with his usual sagacity, 

 he searches out and marks the situation 

 of places according to their latitudes and 

 longitudes ; and he was the first that did 

 so/ Though this work must needs fall 

 far short of perfection, through the want 

 of necessary observations, yet it is of con- 

 siderable merit, and has been very useful 

 to modern geographers. Cellarius, in- 



deed, suspects, and he was a very corrt 

 petent judge, that Ptolemy did not use 

 all the care and application which the na- 

 ture of his work required ; and his reason 

 is, that the author delivers himself with 

 the same fluency and appearance of cer- 

 tainty, concerning things and places at 

 the remotest distance, which it was im- 

 possible he could know any thing of, that 

 he does concerning those which lay the 

 nearest to him, and fall the most under 

 his cognizance. Salmasius had before 

 made some remarks to the same purpose 

 upon this work of Ptolemy. The Greek 

 text of this work was first published by 

 itself at Basil, in 1533, in quarto : after- 

 wards with a Latin version, and notes, by 

 Gerard Mercator, at Amsterdam, 1605 ; 

 which last edition was reprinted at the 

 same place, 1618, in folio, with neat geo- 

 graphical tables, by Bertius. 



Other works of Ptolemy, though less 

 considerable than these two, are still ex- 

 tant. As, "Libri quatuorde Judicils Ys- 

 trorum," upon the first two books of 

 which Cardan wrote a commentary ; 

 ' Fructus Librorum suorum," a kind of 

 supplement to the former work ; " Re- 

 cent io Chronologica Regum ;" this, with 

 another work of Ptolemy, " De Hypo- 

 thesibus Planetarum," was published in 

 1620, 4to., by John Bainbridge, the Savi- 

 lian Professor of Astronomy at Oxford, 

 and Scaliger, Petavius, Dodwell, and the 

 other chronological writers, have made 

 great use of it; '* Apparentiae Stellarum 

 Inerrantium ;" this was published at Paris 

 by Petavius, with a Latin version, 1630, 

 in folio ; but from a mutilated copy, the 

 defects of which have since been supplied 

 from a perfect one, which Sir Henry Sa- 

 ville had communicated to Archbishop 

 Usher, by Fabricius, in the third volume 

 of his Bibliotheca Grseea ; " Elementarum 

 Harmonicarum libri tres," published in 

 Greek and Latin, with a commentary, by 

 Porphyry, the philosopher, by Dr. Wal- 

 lis, at Oxford, 1682, in 4to. ; and after- 

 wards reprinted there, and inserted in 

 the third volume of Wallis's works, 1699, 

 in folio. 



Mabillon exhibits, in his German Tra- 

 vels, an effigy of Ptolemy looking at the 

 stars through an optical tube ; which 

 effigy, he says, he found in a manuscript 

 of the thirteenth century, made by Con- 

 radus, a monk. Hence, some have fan- 

 cied, that the use of the telescope was 

 known to Conradus. But this is only 

 matter of mere conjecture, there being 

 no facts or testimonies, nor even proba- 

 blities, to support such an opinion. 



