Copy letter from Herbert Rix, to Dr John Hopkinson, Fellow of the Royal Society 'Dear Sir, We are authorised to proceed with the printing of the paper by yourself and Mr Wilson. Before I put it into the printers' hands, I should like to know whether you wish to have the manuscript for modification or correction beforehand or whether this is to be done in the proof. I am, yours truly, H Rix Asst. Sec. R.S. [Assistant Secretary, Royal Society]'. 12 December 1895