of clouds and fog, of rain or rivers, and its delightful expanses of perennial deserts, varied towards the poles by a scanty snow-fall in winter, the melting of which might, with great care, supply us with the necessary moisture to grow wheat and cabbages for about one-tenth, or more likely one-hundredth, of our present population.
I hope I may be excused for not treating such an argument seriously.
The various considerations now advanced, especially those which show the enormous cumulative and conservative effect of our dense and water-laden atmosphere, and the disastrous effect—judging by the actual condition of the moon—which the loss of it would have upon our temperature, seem to me quite sufficient to demonstrate important errors in the data or fallacies in the complex mathematical argument by which Mr. Lowell has attempted to uphold his views as to the temperature and consequent climatic conditions of Mars.
In concluding this portion of my discussion of the problem of Mars, I wish to call attention to the fact that my argument, founded upon a comparison of the physical conditions of the earth and moon with those of Mars, is dependent upon a small number of generally admitted scientific facts; while the conclusions drawn from those facts are simple and direct, requiring no mathematical know-
