Large inverted microscope, c 1870.
© Science Museum / Science & Society Picture Library
This microscope owes its peculiar distinction to the great distance (up to nearly 40 inches) between the objective and the eyepiece, enabling very large magnifications to be obtained. The key feature of this microscope is that it is inverted; the object to be observed is placed on top and viewed from underneath, via a mirror in the base that reflects light along the angled tubes to the eyepiece. Inverted microscopes were, and are, often used in metallurgy and petrology. This instrument was made by Nachet et Fils, Paris.