Image description: Mary Halleck Greenewalt (1871-1950) was a gifted pianist with an inquisitive mind. By the early 1900s, she began her investigations into the application of gradated colored light to enhance the emotional expression of music. By 1920 Greenewalt secured the first of many patents for an organ designed to project a sequence of colored lighting arranged for specific musical compositions.
In the first image, a handwritten caption details the experiment demonstrated in the photograph of Greenewalt at her color organ. The copyright stamp at the lower left identifies the photographer as William Shewell Ellis (1876–1931). According to its caption, the ink and watercolor sketch in the second image demonstrates a “mapping out of color sequences” to music of the 19th-century French composer Claude Debussy. The final image shows a page on which is mounted a “light scoring” with extensive explanatory notes below.