Note 531 — Chapter I

The astronomical cubit of the ancients equalled 2 degrees. It therefore follows that in the regions alluded to by Hipparchus, the sun at the winter solstice rose no higher than 18 degrees above the horizon. This would give a latitude of a little above 48 degrees. We afterwards find that Hipparchus placed the mouth of the Dnieper, and that part of France here alluded to, under 48° 29′ 19″, and we know that at this latitude, which is only 20′ 56″ different from that of Paris, there is no real night during the longest days of the summer.