These books were written in 1923. Haldane, a distinguished biochemist and evolutionist, originally wrote Daedalus as a lecture to a Cambridge club known as the ``Heretics'', and later expanded it for publication. Icarus was the response evoked from Bertrand Russell, one of the greatest philosophers of the century. As John Brunner pointed out in an article in the New Scientist in 1993, these two books, together with the physicist J. D. Bernal's The World, the Flesh and the Devil, inspired two generations of science fiction writers, including Mr. Brunner's own Stand on Zanzibar. It is easy to see why: despite the passing of three generations, the futures they suggest remain vivid and plausible; in some aspects, arguably, actual. It is a remarkable and somewhat disquieting achievement.
A word about copyright. Both were copyrighted by the publishing firm E. P. Dutton, Daedalus in 1923 and Icarus in 1924. I can find no record of this copyright being renewed when it expired, 28 years later. By then they were two decades out of print. Nor, apparently, was copyright transferred to either Haldane or Russell. As far as I can determine, these texts are public domain.