Chapter I
Reading edition
EARLY OBSERVERS OF MARS, —Mars the only planet the surface of which is distinctly visible —Early observation of the snow-caps and seas —The 'canals' seen by Schiaparelli in 1877 —Double canals first seen in 1881 —Round spots at intersection of canals seen by Pickering in 1892 —Confirmed by Lowell in 1894 —Changes of colour seen in 1892 and 1894 —Existence of seas doubted by Pickering and Barnard in 1894.