Turn your world upside down! Thomas Jefferson initially used his English concave mirror to concentrate light for investigations with his microscope. Since it reflected people and objects upside down, it ultimately became more of a delightful curiosity, earning a place in Monticello’s Entrance Hall later in his life. Our beautiful adaptation of the concave mirror has a mahogany frame. Imported. 13½" dia., 1½"d.
Thomas Jefferson intended using his concave mirror, as well as the condensing lenses and scioptric ball he bought in London in 1786, with his microscopes. As he wrote in 1822, "in microscopic observations, the enlargement of the angle of vision may be more indulged, because auxiliary light may be concentrated on the object by concave mirrors." The reflecting mirror of a compound microscope would be placed at the focal point of the mirrors.
When a viewer stands outside the focal point of a concave mirror, his image is reflected upside down. This optical phenomenon may account for the mirror's location in the Entrance Hall in an inventory prepared shortly after Jefferson's death. The concave mirror might have become a source of family entertainment in Jefferson's last years, when he had abandoned more complex scientific experiments.