observed the planet from the summit of a mountain in Arizona, using an 18-inch refracting telescope and every resource of delicate measurement and spectroscopy. So superb a climate favoured them that for ten months the planet was kept under continual observation. Over 900 drawings were made and not only were Schiaparelli's channels confirmed, but they added 116 to his 79, on that portion of the planet visible at that opposition. They made the further important discovery that the lines do not stop short at the dark regions of the planet's surface, as hitherto believed, but go right on in many cases; the curvature of the lines being unaltered. Lowell is an uncompromising advocate of the "canal" theory. If his arguments are correct we have at once an answer to our question, "Are there other minds than ours?" We must consider a moment Lowell's arguments; not that it is my intention to combat them. You must form your own conclusions. I shall lay before you another and, as I venture to think, more adequate hypothesis in explanation of the channels of Schiaparelli. We learn, however, much from Lowell's book--it is full of interest.[1] Lowell lays a deep foundation. He begins by showing that Mars has an atmosphere. This must be granted him till some counter observations are made. [1] _Mars_, by Percival Lowell (Longmans, Green & Co.), 1896, 168 It is generally accepted. What that atmosphere is, is another matter. He certainly has made out a good case for the presence of water as one of its constituents, It was long known that Mars possessed white regions at his poles, just as our Earth does. The waning of these polar snows--if indeed they are such--with the advance of the Martian summer, had often been observed. Lowell plots day by day this waning. It is evident from his observations that the snowfall must be light indeed. We see in his map the south pole turned towards us. Mars in perihelion always turns his south pole towards the sun and therefore towards the Earth. We see that between the dates June 3rd to August 3rd--or in two months--the polar snow had almost completely vanished. This denotes a very scanty covering. It must be remembered that Mars even when nearest to the sun receives but half our supply of solar heat and light. But other evidence exists to show that Mars probably possesses but little water upon his surface. The dark places are not water-covered, although they have been named as if they were, indeed, seas and lakes. Various phenomena show this. The canals show it. It would never do to imagine canals crossing the seas. No great rivers are visible. There is a striking absence of clouds. The atmosphere of Mars seems as serene as that of Venus appears to be cloudy. Mists and clouds, however, sometime appear to veil his face and add to the difficulty of 169