Copy letter from Herbert Rix, to James Edward Henry Gordon, 11 Pall Mall, S.W. 'Dear Sir, Our electricians, Messrs Drake & Gorham, state in reply to your query that the voltage available at the Royal Society is 60. If you can arrange your apparatus so as to be suitable for this voltage we can give you the current required. I should be glad to hear from you whether this will meet your requirements. Yours truly, Herbert Rix Asst. Sec. [Assistant Secretary]'. 18 April 1891