Sir Robert Ball cannot conceive how Mars, a much older planet, should develop synchronously with the Earth creatures of intelligence, an event which he insists should have occurred ages earlier in its history. In this supposition he is quite right, for if there are creatures of intelligence in Mars these should have appeared much earlier, and that is probably what has happened. The problem is one parallel to that urged by Sir Boyd Dawkins in regard to the evidences of man in the Tertiary rocks. Dawkins argued that since the mammals in the Tertiary had changed so profoundly, many types becoming extinct, if man had lived at that time he also should have been affected by the same influences, and should have changed accordingly. It has been clearly pointed out by Cope and others that the moment intelligence became a factor in natural selection it was seized upon to the relative exclusion of physical characteristics, hence but little change, otherwise than an intellectual one, has taken place in man since his progenitors took to the trees and made up by agility, cunning, and alertness what they lacked in physical strength. In the same way, if, in the past history of Mars, an intelligent creature appeared he must have survived under precisely similar conditions, and long after favorable environments had passed that were implicated in making him what he was. Admitting that there is an intelligent creature of some kind in Mars, is it reasonably conceivable that he should have caused such changes in the surface features of that planet as to be visible from the Earth? Professor Newcomb concludes, in a recent article in "Harper's Magazine," that "we cannot expect to see any signs of the works of inhabitants in Mars, if such exist." Let us, however, reverse the proposition and ask ourselves if man has been implicated in any changes in the surface appearance of the Earth that would be visible from Mars? And I think the question can be answered in only one way. The vast cities such as Pekin, Tokio, London, and New York, with their great expanse of tiled and slated roofs, and sterile streets, would certainly have a different albedo from the grass and trees in the immediate outskirts of such places. The tracts of land reclaimed from the sea, and still more the enormous areas which have been rendered green by irrigation, must, of all contrasts, be markedly conspicuous. To realize the extent of this work, it is only necessary to state that in Egypt 6,000,000 acres depend upon irrigation, and this area to be vastly increased in a short time; the Western states of America with 10,000,000 acres, and this area being rapidly augmented by the work of the United States Reclamation Bureau; in India 25,000,000 acres under irrigation, and this being continually added to; above all, however, the vast extent of territory from which the dark forests have been removed in this country, and more particularly in China, must make a visible landmark.