Page:Is Mars habitable - Wallace 1907.djvu/50

 the tapping of the snow-cap for the water there semi-annually let loose; then to distribute it over the planet's face" (p. 373).

Here, again, we have curiously weak arguments adduced to support the view that these numerous straight lines imply works of art rather than of nature, especially in the comparison made with the belts of Jupiter and the spots on the sun, both purely atmospheric phenomena, whereas the lines on Mars are on the solid surface of the planet. Why should there be any resemblance between them? Every fact stated in the above quotation, always keeping in mind the physical conditions of the planet—its very tenuous atmosphere and rainless desert-surface—seem wholly in favour of a purely natural as opposed to an artificial origin; and at the close of this discussion I shall suggest one which seems to me to be at least possible, and to explain the whole series of the phenomena set forth and largely discovered by Mr. Lowell, in a simpler and more probable manner than does his tremendous assumption of their being works of art. Readers who may not possess Mr. Lowell's volume will find three of his most recent maps of the 'canals' reproduced in Nature of October 11th, 1906.