Second letter from George Howard Darwin, to John William Strutt, Lord Rayleigh, regarding a paper 'On the straining of the Earth resulting from secular cooling' by Charles Davison Has corresponded with William Thomson, 1st Baron Kelvin, and agree that the paper should 'begin with an explanation or proof of the possibility of the existence of a cooling sphere, with uncracked surface, whose surface is maintained at constant low temperature'. Subject: Mathematics, Physics and Chemistry [Published in the 'Proceedings of the Royal Society of London', 1894] 29 October 1894