The proportion of water to land is much smaller on Mars than on the earth. Only two-sevenths of the disk are covered by the dusky areas, and of late the aqueous nature of some, if not all, of these has been seriously called in question. Professor Pickering was convinced by his observations, in 1892 and 1894, “that the permanent water area upon Mars, if it exist at all, is extremely limited in its dimensions.” He estimated it at about half the size of the Mediterranean. Professor Schaeberle is similarly incredulous. If the dark markings are seas, he asks, how explain the irregular gradations of shade in them? How, above all, explain their apparent intersection by well-marked canals? Professor Barnard, observing with the Lick thirty-six inch in 1894, discerned on the Martian surface an astonishing wealth of detail, “so intricate, small, and abundant, that it baffled all attempts to properly delineate it.” It was embarrassing to find these minute features belonging more characteristically to the “seas” than to the “continents.” Under the best conditions, the dark regions lost all trace of uniformity. Their appearance resembled that of a mountainous country, broken by cañon, rift, and ridge, seen from a great elevation. These effects were especially marked in the “ocean” area of the Hour-Glass Sea. Evidently the relations of solid and liquid in that remote orb are abnormal; they can not be completely explained by terrestrial analogies. Yet a series of well-attested phenomena are intelligible only on the supposition that Mars is, in some real sense, a terraqueous globe. Where snows melt there must be water; and the origin of the Rhone from a great glacier is scarcely more evident to our senses than the dissolution of Martian ice-caps into pools and streams. The testimony of the spectroscope is to the same effect. Dr. Huggins found, in 1867, the spectrum of Mars impressed with the distinct traces of aqueous absorption, and the fact, although called in question by Professor Campbell of Lick, in 1894, has been reaffirmed both at Tulse Hill and at Potsdam. That clouds form and mists rise in the thin Martian air, admits of doubt. During the latter half of October, 1894, an area much larger than Europe remained densely obscured. Whether or no actual rain was at that time falling over the Maraldi Sea and the adjacent continent it would be useless to conjecture. We only know that with the low barometric pressure at the surface of Mars, the boiling point of water must be proportionately depressed (Flammarion puts it at 115° Fahrenheit), which implies that it evaporates rapidly, and can be transported easily.