Louis Pasteur's First Microscope?
This French microscope was almost certainly made by a member of the Chevalier family of instrument makers, circa 1840. "L.Pasteur" is stamped into the underside of the lead weighted base.
Louis Pasteur was familiar with Chevalier's shop in the Palais Royal as a young student in Paris and favoured simple continental microscopes throughout his life.
Additional information to follow.