evolution at a rate more rapid than would be possible with a larger globe like the earth. The sea is constantly wearing down the land, but by upheavals arising from the intensely heated condition of the interior of our globe the land is still able to maintain itself above water. It can, however, hardly be doubted, that if our earth had so far cooled that the upheavals had either ceased or were greatly reduced, the water would greatly encroach on the land. On a small globe like Mars the cooling of the interior has so far advanced that, in all probability, the internal heat is no longer an effective agent for indirectly resisting the advance of the water, and, consequently, the observed submergence is quite to be expected.
That there may be types of life on Mars of some kind or other is, I should think, very likely. Two of the elements, carbon and hydrogen, which are most intimately associated with the phenomena of life here, appear to be among the most widely distributed elements throughout the universe, and their presence on Mars is in the highest degree probable. But what course the progress of evolution may have taken on such a globe as Mars, it seems totally impossible to conjecture. It has been sometimes thought that the ruddy colour of the planet may be due to vegetation of some peculiar hue, and there is certainly no impossibility in the conception that vast forests of some such trees as copper-beeches might impart to continental masses hues not unlike those which come from Mars. Speculations have also been made as to the possibility of there being intelligent inhabitants on this planet, and I do not see how anyone can deny the possibility at all events of such a fact. I would suggest, however, that as our earth has only been tenanted by intelligent beings
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