Copy letter from Herbert Rix, to Gebr Gotthelft, Verlagshandlung, Cassel 'Dear Sir, I have this day paid into the post-office £1-8s-0 which will be transmitted to you to defray the enclosed account. Kindly receipt the account & return it to me. Yours truly Herbert Rix Asst. Sec. R.S. [Assistant Secretary, Royal Society]'. 2 June 1891