— William Thomson British physicist and engineer 1824 - 1907
As a response to Major B. F. S. Baden Powell's request to join the Aeronautical Society, December 8, 1896 http://zapatopi.net/kelvin/papers/letters.html#baden-powell.
Often reproduced out of context and without citation to any primary source as "Heavier-than-air flying machines are impossible", like in The Experts Speak : The Definitive Compendium of Authoritative Misinformation (1984) by Christopher Cerf and Victor Navasky, p. 236
Kontext: I am afraid I am not in the flight for “aerial navigation”. I was greatly interested in your work with kites; but I have not the smallest molecule of faith in aerial navigation other than ballooning or of expectation of good results from any of the trials we hear of. So you will understand that I would not care to be a member of the aëronautical Society.