Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to J. Brookes Esquire; 17 Honiton Road, Romford, Essex Reply to an earlier enquiry from Brookes into the Thermophone. States that the Royal Society have no knowledge of the manufacture of the Thermophone, but that his enquiry has been passed onto M. de Lange who is better suited to help. 13 October 1915