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 CHAPTER V. THE TEMPERATURE OF MARS—MR. LOWELL'S ESTIMATE.

have now to consider a still more important and fundamental question, and one which Mr. Lowell does not grapple with in this volume, the actual temperatures on Mars due to its distance from the sun and the atmospheric conditions on which he himself lays so much stress. If I am not greatly mistaken we shall arrive at conclusions on this subject which are absolutely fatal to the conception of any high form of organic life being possible on this planet.

The Problem of Terrestrial Temperatures.

In order that the problem may be understood and its importance appreciated, it is necessary to explain the now generally accepted principles as to the causes which determine the temperatures on our earth, and, presumably, on all other planets whose conditions are not wholly unlike ours. The fact of