The book of the lantern : being a practical guide to the working of the optical (or magic) lantern : with full and precise directions for making and coloring lantern pictures (1889)
Hepworth, Thomas Cradock, -1905 · New York : E.L. Wilson · leaf 140
118 THE BOOK OF THE LANTERN. other words, " the intensity of illumination on a given sur- face is inversely as the square of its distance from the source of light." … Fig. 39. Fig. 39 will perhaps make the matter still more plain. At 1 foot from the candle the square marked i receives a certain amount of light ; at II, that light is spread over a surface four times the area of the first ; and at in over a surface nine times as large as I. This law, which is…
Lantern projection
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
