oximated by analogy or probable conjecture,
between the most remarkable places on its surface, adds, that Eratosthenes,
whose acuteness and application had advanced him far in every branch of
knowledge, but who had outstripped all his predecessors or contemporaries
in that particular branch which was connected with the admeasurement of the
earth, had fixed its circumference at 250,000 stadia; a bold and almost
presumptuous enterprize, (_improbum ausum_,) but which had been conducted
with so much judgment, and on such sound principles, that it commanded and
deserved our credit. Hipparchus, who was distinguished for his correctness
and diligence in every part of geometrical and astronomical science, and
who had specially exerted those qualities in his endeavours to correct the
errors of Eratosthenes, had been able to add only the comparatively small
extent of 25,000 stadia to the computation of Eratosthenes.--_Plin. Nat.
Hist._ lib. ii. c. 108.

Eratosthenes seems, from the nature of his studies, not to have availed
himself so much as he might have done of the treasures contained in the
Alexandrian library under his care, to correct or extend the geographical
knowledge of his contemporaries. The same observation will not apply to
Agatharcides, who was president of the library after Eratosthenes. The
exact time at which he flourished is not known: according to Blair, he was
contemporary with Eratosthenes, though younger than him, and flourished 177
A.C., Eratosthenes having died at the age of eighty-one, in the year 194
A.C. Dodwell, however, fixes him at a later period; viz. 104 A.C.; but this
date must be erroneous, because Artemidorus of Ephesus, who evidently
copies Agatharcides, undoubtedly lived 104 A.C. Agatharcide's was born at
Cnidus in Caria: no particulars are known respecting him, except that he
was president of the Alexandrian library, in the reign of Ptolemy
Philometor, if he flourished 177 A.C.; and in the reign of Ptolemy
Lathyrus, if, according to Dodwell, he did not flourish till 104 A.C.

The only work of his which is preserved, is a Treatise on the Erythraean
Sea; and this we possess only in the Bibliotheca of Photius, and
incorporated in the history of Diodorus Siculus. The authority of
Agatharcides was very high among the ancients. Strabo, Pliny, and Diodorus,
always mention him with the utmost respect, and place implicit confidence
in his details. Diodorus expressly states that Agatharcides and Artemi