Broadstone, Wimborne. August 10, 1907.
My dear Barrett,—Thanks for your letter, and your friend Prof. Stroud's. I have come to the sad conclusion that it is hopeless to get any mathematician to trouble himself to track out Lowell's obscurities and fallacies.... So, being driven on to my own resources, I have worked out a mode of estimating (within limits) the temperature of Mars, without any mathematical formulæ—and only a little arithmetic. I want to know if there is any fallacy in it, and therefore take the liberty of sending it to you, as you are taking your holiday, just to read it over and tell me if you see any flaw in it. I also send my short summary of Lowell's Philosophical Magazine paper, so that you can see if my criticism at the end is fair, and whether his words really mean what to me they seem to....—Yours very sincerely,
ALFRED R. WALLACE.
TO MR. F. BIRCH
Sept. 12, 1907.
Dear Fred,— ... For the last two or three months I have had a hard struggle with Mars—not the god of war, but the planet—writing a small book, chiefly criticising Lowell's last book, called "Mars and its Canals," published less than a year back by Macmillan, who will also publish my reply. I think it is crushing, but it has cost me a deal of trouble, as Lowell has also printed a long and complex mathematical article trying to prove that though Mars receives less than half the sun-heat we do, yet it is very nearly as warm and quite habitable! But his figures and arguments are alike so shaky and involved that I cannot get any of my mathematical friends to tackle it or point out his errors. However, I think I have done it myself by the rules of common sense....—Your sincere friend,
ALFRED R. WALLACE.