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 cord 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 quatuor de Judiciis As trorum," upon the first two books of which Cardan wrote a commentary ; " Fructus Librorum suorum," a kind of supplement to the former work ; " Re centio 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 ; "Apparentiz 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 Grzea ; " Element...arum 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.
-It is likely that the tube was nothing more than a plain open one, employed to strengthen and defend the eyesight, when looking at particular stars, by excluding adventitious rays from other stars and ob jects, a contrivance which no observer of the heavens can ever be supposed to have been without..