(To the Editor of "The Daily News.")

     Sir,--I do not think that Mr. Sanders, who writes in your columns on "Life in Mars," can have read my little book. His argument against carbon-dioxide being the cause of the snows assumes that the whole atmosphere must be of that gas, which nobody has supposed. All his other "difficulties" are fully answered in the book, while his statement as to the pressure required for CO₂ to exist at all in the liquid state is erroneous, as he takes no account of temperature nor of other conditions.--Yours, etc.,

Alfred R. Wallace.
Jan. 24.