Copy letter from Herbert Rix, to Professor Walter Frank Raphael Weldon, Fellow of the Royal Society 'Dear Sir, Our electricians want to know whether you intend putting your lamps under water or at the back of the tanks when you exhibit for us in June. Will you kindly answer this question at your leisure? Yours truly Herbert Rix Asst Sec RS [Assistant Secretary, Royal Society]'. 16 April 1891