e done to him at the taking of the town, and
that he was killed, unfortunately, by an ignorant soldier--unfortunately,
for Europe was not able to produce his equal for nearly two thousand years.

[Sidenote: The writings and works of Eratosthenes.]

Eratosthenes was contemporary with Archimedes. He was born at Cyrene,
B.C. 276. The care of the library appears to have been committed to him
by Euergetes; but his attention was more specially directed to
mathematical, astronomical, geographical, and historical pursuits. The
work entitled "Catasterisms," doubtfully imputed to him, is a catalogue
of 475 of the principal stars; but it was probably intended for nothing
more than a manual. He also is said to have written a poem upon
terrestrial zones. Among his important geographical labours may be
mentioned his determination of the interval between the tropics. He
found it to be eleven eighty-thirds of the circumference. He also
attempted the measurement of the size of the earth by ascertaining the
distance between Alexandria and Syene, the difference of latitude
between which he had found to be one-fiftieth of the earth's
circumference. It was his object to free geography from the legends with
which the superstition of ages had adorned and oppressed it. In
effecting this he well deserves the tribute paid to him by Humboldt, the
modern who of all others could best appreciate his labours. He
considered the articulation and expansion of continents; the position of
mountain chains; the action of clouds; the geological submersion of
lands; the elevation of ancient sea-beds; the opening of the Dardanelles
and of the Straits of Gibraltar; the relations of the Euxine Sea; the
problem of the equal level of the circumfluous ocean; and the necessary
existence of a mountain chain running through Asia in the diaphragm of
Dicaearchus. What an advance is all this beyond the meditations of
Thales! Herein we see the practical tendencies of the Macedonian wars.
In his astronomical observations he had the advantage of using the
armils and other instruments in the Observatory. He ascertained that
the direction of terrestrial gravity is not constant, but that the
verticals converge. He composed a complete systematic description of the
earth in three books--physical, mathematical, historical--accompanied by
a map of all the parts then known. Of his skill as a geometer, his
solution of the problem of two mean proportionals, still extant, offers
ampl