1899 introductions

alt=C8 style on the left, tube style on the right|thumb|A set of modern LED flashlights

door, typically consists of three or four doors that hang on a central shaft and rotate around a vertical axis within a cylindrical enclosure

chemical reaction

critical criterion for evaluating a historical account's veracity

constructed language

thumb|1909 flash-lamp 1903 view camera thumb|Crop of patent number 636,492