Copy letter from Herbert Rix, to Trotter, Editor "The Electrician" 'Dear Sir, Will you kindly give to our printer's messenger (who brings this note) cliché of the enclosed figure. Sir William Thomson writes me that you will probably be willing to send it to us to illustrate Sir William's paper in our "Proceedings" ['Proceedings of the Royal Society']. Kindly return by the messenger the proof with the cliché. Yours truly, Herbert Rix Asst. Sec. R.S. [Royal Society]'. 6 April 1891