work
had to be brought from a great distance. The Alexandrian light-house was
reared in the time of Ptolemy Philadelphus, the second monarch in the
line. No pains or expense were spared in its construction. The edifice,
when completed, was considered one of the seven wonders of the world. It
was indebted for its fame, however, in some degree, undoubtedly to the
conspicuousness of its situation, rising, as it did, at the entrance of
the greatest commercial emporium of its time, and standing there, like a
pillar of cloud by day and of fire by night, to attract the welcome gaze
of every wandering mariner whose ship came within its horizon, and to
awaken his gratitude by tendering him its guidance and dispelling his
fears.

The light at the top of the tower was produced by a fire, made of such
combustibles as would emit the brightest flame. This fire burned slowly
through the day, and then was kindled up anew when the sun went down,
and was continually replenished through the night with fresh supplies of
fuel. In modern times, a much more convenient and economical mode is
adopted to produce the requisite illumination. A great blazing lamp
burns brilliantly in the center of the lantern of the tower, and all
that part of the radiation from the flame which would naturally have
beamed upward, or downward, or laterally, or back toward the land, is so
turned by a curious system of reflectors and polyzonal lenses, most
ingeniously contrived and very exactly adjusted, as to be thrown forward
in one broad and thin, but brilliant sheet of light, which shoots out
where its radiance is needed, over the surface of the sea. Before these
inventions were perfected, far the largest portion of the light emitted
by the illumination of light-house towers streamed away wastefully in
landward directions, or was lost among the stars.

Of course, the glory of erecting such an edifice as the Pharos of
Alexandria, and of maintaining it in the performance of its functions,
was very great; the question might, however, very naturally arise
whether this glory was justly due to the architect through whose
scientific skill the work was actually accomplished, or to the monarch
by whose power and resources the architect was sustained. The name of
the architect was Sostratus. He was a Greek. The monarch was, as has
already been stated, the second Ptolemy, called commonly Ptolemy
Philadelphus. Ptolemy ordered that, in completing the tower, a marble
tablet s