1837-1839: AGE 30-32.
Invitation to Professorships at Geneva and Lausanne.--Death of his
Father.--Establishment of Lithographic Press at Neuchatel.
--Researches upon Structure of Mollusks.--Internal Casts of Shells.
--Glacial Explorations.--Views of Buckland.--Relations with Arnold
Guyot.--Their Work together in the Alps.--Letter to Sir Philip
Egerton concerning Glacial Work.--Summer of 1839.--Publication of
"Etudes sur les Glaciers."