Letter, from Emilien Frossard Pasteur to Sir John Herschel, dated at Bagnieres de Biguerre Autograph letter signed by sender. Remembers when John Frederick William Herschel introduced him to the Museum of Geology in Jermyn St.. Would like to exchange some rocks and minerals for some English fossils. Can John Frederick William Herschel advise him to whom to write? 18 September 1868