_Is Mars Habitable?_

A CRITICAL EXAMINATION OF PROFESSOR PERCIVAL LOWELL'S BOOK
"MARS AND ITS CANALS," WITH AN ALTERNATIVE EXPLANATION

BY ALFRED RUSSEL WALLACE F.R.S., ETC.



PREFACE.

This small volume was commenced as a review article on Professor
Percival Lowell's book, _Mars and its Canals_, with the object of
showing that the large amount of new and interesting facts contained in
this work did not invalidate the conclusion I had reached in 1902, and
stated in my book on _Man's Place in the Universe_, that Mars was not
habitable.

But the more complete presentation of the opposite view in the volume
now under discussion required a more detailed examination of the various
physical problems involved, and as the subject is one of great, popular,
as well as scientific interest, I determined to undertake the task.

This was rendered the more necessary by the fact that in July last
Professor Lowell published in the _Philosophical Magazine_ an elaborate
mathematical article claiming to demonstrate that, notwithstanding its
much greater distance from the sun and its excessively thin atmosphere,
Mars possessed a climate on the average equal to that of the south of
England, and in its polar and sub-polar regions even less severe than
that of the earth. Such a contention of course required to be dealt