friend of Menedemus and Aratus; and it is not
easy to believe that these lines were written before the overthrow of
Hannibal in Italy, and of the Greek phalanx at Cynocephale, or that
one who was a man in the reign of Philadelphus should have foreseen the
triumph of the Roman arms. These words must have been a later addition
to the poem, to improve the prophecy.

Conon, one of the greatest of the Alexandrian astronomers, has left no
writings for us to judge of his merits, though they were thought highly
of, and made great use of, by his successors. He worked both as an
observer and an inquirer, mapping out the heavens by his observations,
and collecting the accounts of the eclipses which had been before
observed in Egypt. He was the friend of Archimedes of Syracuse, to
whom he sent his problems, and from whom he received that great
geometrician's writings in return.

Apollonius of Perga came to Alexandria in this reign, to study
mathematics under the pupils of Euclid. He is well known for his work
on conic sections, and he may be called the founder of this study.
The Greek mathematicians sought after knowledge for its own sake, and
followed up those branches of their studies which led to no end that
could in the narrow sense be called useful, with the same zeal that they
did other branches out of which sprung the great practical truths of
mechanics, astronomy, and geography. They found reward enough in the
enlargement of their minds and in the beauty of the truth learnt.
Alexandrian science gained in loftiness of tone what its poetry and
philosophy wanted. Thus the properties of the ellipse, the hyperbola,
and the parabola, continued to be studied by after mathematicians; but
no use was made of this knowledge till nearly two thousand years later,
when Kepler crowned the labours of Apollonius with the great discovery
that the paths of the planets round the sun were conic sections.
The Egyptians, however, made great use of mathematical knowledge,
particularly in the irrigation of their fields; and Archimedes of
Syracuse, who came to Alexandria about this time to study under Conon,
did the country a real service by his invention of the cochlea, or
screw-pump. The more distant fields of the valley of the Nile, rising
above the level of the inundation, have to be watered artificially by
pumping out of the canals into ditches at a higher level. For this work
Archimedes proposed a spiral tube, twisting round an axis, which wa