A Valentin knife, English, c 1840.
© Science Museum / Science & Society Picture Library
Manufactured from nickel plated steel, with double blades and a sliding adjuster. Valentin knives were used to cut very thin slices of tisue for microscopic examination. They were named after Gabriel Gustav Valentin (1810-1883) of Bern, Switzerland, who by 1838 had observed the proces of cell division.