Introductory Astronomical Writings of the Ancients

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[those who] dwell [among us], the summer tropic circle is cut by the horizon into more equal parts. And there is a limit, a certain region situated to our south, in which the summer tropic circle is bisected by the horizon. But in our own habitation, the summer tropic is cut by the horizon in such a way that, the whole circle being divided into eight parts, five segments are contained above the earth, and three beneath the earth. It seems that Aratus, too, composed his treatise The Phenomena with reference to this climate. For, discoursing upon the summer tropic circle, he speaks thus:

Of this, as much as has been measured out by eight,
Five revolve above the heights of the earth,
And three in the depths. And therein are the turnings of summer.

From this division, it follows that the longest day consists of fifteen equinoctial hours, and the night of nine equinoctial hours. In the horizon at Rhodes, however, the summer tropic circle is cut by the horizon in such a way that, the whole circle being divided into forty-eight parts, twenty-nine segments are contained above the horizon, and nineteen beneath the earth. From this division, it follows that in Rhodes the longest day consists of fourteen and a half equinoctial hours, and the night of nine and a half equinoctial hours. The equinoctial circle is bisected by the horizon throughout the whole inhabited world, so that a semicircle is contained above the earth, and a semicircle beneath the earth. For which reason the equinoxes occur upon this circle. But the winter tropic circle