GEOLOGISTS and MINERALOGISTS. 5 letters Charles SAINTE-CLAIRE-DEVILLE (on the letterhead of the Montsouris Observatory, on the shipment of thermometers), André LAUGIER (on the subject of notes forgotten at the Academy), Alfred LACROIX (application for a vacant position), Albert GAUDRY (to a colleague on bibliographical research), Samuel HOPKINS (Geneva, 1834). Old engravings and an autograph visiting card from the mining engineer Michel LÉVY are enclosed.