Letter from [Alan Archibald Campbell] Swinton, to [Harry Raplh] Ricardo Informs he has heard from the Directors of his Bath Electric Tramways Company that crude oil for commercial motor car work is being successfully used by the A. E. C. Company, and that the main factor in the use of crude oil appears to be a form of organised disturbance. Asks if there can be any valid patent and anything else Ricardo knows about the matter. 2 January 1930