Page:Mars - Lowell.djvu/119

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AREOGRAPHY

and east to the left. Mars rotates as the Earth does, from west to east, so that day as it advances across the face of the planet follows the order here shown in Plates III. to XIV., the order in which we shall observe them. Places on the right of the picture are in the morning of their Martian day; places on the left, in its afternoon. To facilitate reference by longitude and latitude, the globe has been belted by meridians and parallels each 10° apart, and the meridians have been numbered along the equator. This premised, we will suppose ourselves to be standing on the equator at its intersection with the 0° meridian. (Plate III.)

It will be noticed that the 0° meridian passes through the tip of a triangular peninsula that juts out into a dark area curiously forked, half way across the picture and about two thirds way down it. The tip of this triangle is the received Greenwich of Martian longitudes, and has been named by Schiaparelli the Fastigium Aryn, such having been the name of a mythologic spot supposed by the ancients to lie midway between the east and west, the north and south, the zenith and nadir. It thus makes a fitting name for the starting-point of Martian longitudes and the beginning of Lime. The dark forked area, called by Proctor “Dawes’ Forked Bay,” is now commonly called the Sabaeus Sinus. At the times these marine