r may
have been. His personality is as deeply enveloped in the mists of the
past as are the personalities of the great prehistoric discoverers. For
the purpose of the historian, Eratosthenes must stand as the inventor
of the method with which his name is associated, and as the first man of
whom we can say with certainty that he measured the size of the earth.
Right worthily, then, had the Alexandrian philosopher won his proud
title of "surveyor of the world."

HIPPARCHUS, "THE LOVER OF TRUTH"

Eratosthenes outlived most of his great contemporaries. He saw the
turning of that first and greatest century of Alexandrian science, the
third century before our era. He died in the year 196 B.C., having,
it is said, starved himself to death to escape the miseries of
blindness;--to the measurer of shadows, life without light seemed not
worth the living. Eratosthenes left no immediate successor. A generation
later, however, another great figure appeared in the astronomical world
in the person of Hipparchus, a man who, as a technical observer, had
perhaps no peer in the ancient world: one who set so high a value upon
accuracy of observation as to earn the title of "the lover of truth."
Hipparchus was born at Nicaea, in Bithynia, in the year 160 B.C. His
life, all too short for the interests of science, ended in the year 125
B.C. The observations of the great astronomer were made chiefly, perhaps
entirely, at Rhodes. A misinterpretation of Ptolemy's writings led to
the idea that Hipparchus, performed his chief labors in Alexandria, but
it is now admitted that there is no evidence for this. Delambre doubted,
and most subsequent writers follow him here, whether Hipparchus ever so
much as visited Alexandria. In any event there seems to be no question
that Rhodes may claim the honor of being the chief site of his
activities.

It was Hipparchus whose somewhat equivocal comment on the work of
Eratosthenes we have already noted. No counter-charge in kind could be
made against the critic himself; he was an astronomer pure and simple.
His gift was the gift of accurate observation rather than the gift
of imagination. No scientific progress is possible without scientific
guessing, but Hipparchus belonged to that class of observers with
whom hypothesis is held rigidly subservient to fact. It was not to be
expected that his mind would be attracted by the heliocentric theory of
Aristarchus. He used the facts and observations gathered by his