The first map ever constructed of Mars was drawn by Beer and Mädler in the fortieth year of the last century, and is here numbered I. The observations upon which it was based were made with a four inch telescope and extended in all over eight years. In this map all the main features which we note to-day are unmistakably depicted. The 'Eye of Mars' (the Lake of the Sun) is well seen, as well as the
dark marking that makes eyebrow to it on the south. Next come the Mare Sirenum and the Mare Cimmerium as one long leech-like patch, duly inclined to the parallels. Then follows the Syrtis Major, the first discerned of all the markings on the planet. It was drawn by Huyghens in 1659. Out of it is delineated the Icarium Mare, ending unmistakably in the Sabaæus Sinus seen as a scroll. Dark patches to the south
stand for the Mare Erythræum and sporadic ones in the midst of the great continental areas north give adumbration of the canals and oases later to be discovered there.
The next map, No. II., is Kaiser's, made in 1864. In it it is easy to trace all the fundamental features we have noted in the chart of
