Copy letter from Herbert Rix, to Monsieur le Professor Lippmann, 4 Carrefour de l'Odeon, Paris 'Dear Sir, In answer to your note of yesterday the two spectra which you so kindly lent for exhibition at our Soirée are at present in the hands of Captain [William de Wiveleslie] Abney. I have just written to Captain Abney to ask him to return them to you without delay. The spectra excited great interest among our Fellows and visitors. I am, yours sincerely, Herbert Rix Asst. Sec. R.S. [Assistant Secretary, Royal Society]'. 13 July 1891