able phenomenon of the duplicity in the canals. Professor Schiaparelli has, on the same occasion, confirmed his previous observations, and, notwithstanding that the opposition of 1888 was not really an advantageous one, yet under exceptionally favourable circumstances, he declares that he saw the hemisphere of Mars so exquisitely delineated that the canals had all the distinctness of an engraving on steel, with the magical beauty of a coloured painting.
Speculations have naturally been made as to the explanation of these wonderful canals. It has been suggested that they may indeed be rivers; but it hardly seems likely that the drainage of continents on so small a globe as Mars would require an elaborate system of rivers each sixty miles wide and thousands of miles in length. There is, however, a more fatal objection to the river theory, in the fact that the marks we are trying to interpret sometimes cross a Martian continent from ocean to ocean, while on other occasions they seem to intersect each other. Such phenomena are, of course, well-nigh impossible if these so-called canals were in any respect analogous to the rivers which we know on our own globe. It can, however, hardly be doubted that if we assume the dark regions to be oceans the canals do really represent some extension of the waters of these oceans into the continental masses. Other facts which are known about the planet suggest that what seem to be vast inundations of its continents must occasionally take place. Nor is it surprising that such vicissitudes should occur on a globe circumstanced like Mars. Here again it is well to remember the small size of the planet, from which we may infer that it has progressed through its physical
