| Description | Letter written from The University, Birmingham dated 12 March. Lodge thanks Jack [1873-1951, military cartographer and Director General of the Ordnance Survey Office 1922-1930] for answering his enquiry about hot-wire microphones, and notes that he has decided not to show one. He plans to show the Einthoven Galvanometer but will not mention Bull's timing apparatus as he is not acquainted with the details. |