Copy letter from Herbert Rix, to Walter G Spencer 'Dear Sir, Herewith I send proofs and originals of your three plates. Could you correct and return the proofs together with the originals by Monday? The lithographers could not make out some of the lettering for the diagrams; please put it in quite clearly. Please note that they are to be returned to us, not to the lithographers. I am, yours truly, H Rix Asst. Sec. R.S. [Assistant Secretary, Royal Society]'. 27 July 1894