sian and Red Seas to be. He had formed a resolution
that his fleet should attempt the circumnavigation of Africa, and come
into the Mediterranean through the Pillars of Hercules--a feat which, it
was affirmed, had once been accomplished by the Pharaohs.

INTELLECTUAL CONDITION OF PERSIA. Not only her greatest soldiers, but
also her greatest philosophers, found in the conquered empire much that
might excite the admiration of Greece. Callisthenes obtained in Babylon
a series of Chaldean astronomical observations ranging back through
1,903 years; these he sent to Aristotle. Perhaps, since they were on
burnt bricks, duplicates of them may be recovered by modern research
in the clay libraries of the Assyrian kings. Ptolemy, the Egyptian
astronomer, possessed a Babylonian record of eclipses, going back
747 years before our era. Long-continued and close observations were
necessary, before some of these astronomical results that have reached
our times could have been ascertained. Thus the Babylonians had fixed
the length of a tropical year within twenty-five seconds of the truth;
their estimate of the sidereal year was barely two minutes in excess.
They had detected the precession of the equinoxes. They knew the causes
of eclipses, and, by the aid of their cycle called Saros, could predict
them. Their estimate of the value of that cycle, which is more than
6,585 days, was within nineteen and a half minutes of the truth.

INTELLECTUAL CONDITION OF PERSIA. Such facts furnish incontrovertible
proof of the patience and skill with which astronomy had been cultivated
in Mesopotamia, and that, with very inadequate instrumental means, it
had reached no inconsiderable perfection. These old observers had made
a catalogue of the stars, had divided the zodiac into twelve signs; they
had parted the day into twelve hours, the night into twelve. They had,
as Alistotle says, for a long time devoted themselves to observations of
star-occultations by the moon. They had correct views of the structure
of the solar system, and knew the order of the emplacement of the
planets. They constructed sundials, clepsydras, astrolabes, gnomons.

Not without interest do we still look on specimens of their method of
printing. Upon a revolving roller they engraved, in cuneiform letters,
their records, and, running this over plastic clay formed into blocks,
produced ineffaceable proofs. From their tile-libraries we are still
to reap a literary and historical ha