Note 1 — CANTO XXVII.

From Dante's first look downward from the Heavens, at the end of Canto XXII, to the present moment, he had moved over the arc which the first climate describes from its middle to its end. The old geographers divided the earth into seven zones, called climates, by circles parallel to the equator. The first climate extended twenty degrees to the north of the equator. The sign of the Gemini, in which Dante was revolving in the Heaven of the Fixed Stars, is in the zone of the Heavens corresponding to the first climate. As each climate extended on the habitable hemisphere for one hundred and eighty degrees, the arc from its middle to its end would be of ninety degrees, comprised between Jerusalem and Cadiz, and the time required for passing through it would be six hours, one fourth of the diurnal revolution of the Heavens.