Any instrument for viewing objects in the dark or in a faint light.
August 13th 1664, Samuel Pepys, Diary (London: Marshall Cavendish, 1988), 133.
“Comes Mr. Reeve, with a microscope and scotoscope. […] The other [the scotoscope] he gives me, and is of value; and a curious curiosity it is to discover objects in a dark room with.”