Mary Hallock Greenewalt received 11 patents for her “color organ,” an early form of synthesizer. She would spend the rest of her life defending them. Words and animation at

Patent No. 1,345,168: “Illuminating Means” (1920)
This classical pedestal—shown here with a sculpture of Atlas holding the Earth on his shoulders—contained a gramophone or phonograph, which was adapted to play records and synchronize with lights of graduated tints or colors, which would then illuminate the dome.
“In order that the color scheme can be developed, the rotating table which carries the record disk may be provided with leaves of translucent, colored, or parti-colored materials, overlying the source of illumination and through which the latter may shine,” Greenewalt wrote in her patent, “so that the color may be lessened or intensified, or altered in tint.”
Patent No. 1,357,773: “Rheostat” (1920)
The rheostat was an essential mechanism of the Sarabet. It was an electrical device that varied the resistance of the electrical current so that Greenewalt could produce smooth fade-ups and fade-outs of light as she played. In this patent application, she describes the rheostat as “compact and substantial of a commercially practicable design; relatively simple as regards the aggregate number and arrangement of its parts, and at the same time includes a series of contact blocks and moveable contact member adapted for operation by human, mechanical or automatic power.”
The rheostat would become a standard tool for electronic instruments, and when General Electric infringed on Greenewalt’s patent in 1932, she sued. At first, a judge denied hearing the case, determining that the rheostat was too complex to have been invented by a woman. This decision was overturned on appeal by Judge Hugh Morris, who described Greenewalt as “a true artist” in his decision, and she eventually won the case.

Patent No. 1,945,635: Sarabet (“Light Color Instrument”) (1927)
Greenewalt would file four patents for the Sarabet, of which this was the final. “One object of my invention is to provide a console for a light-color instrument,” she wrote in this patent description. “Another object of my invention is to provide fluid connectors for such an instrument … and to raise or lower a current transmitting fluid about a resistor element for the purpose of increasing or decreasing its resistive action.” The Sarabet received its debut at John Wanamaker’s New York department store in 1922, so that Greenewalt could publicize her console for owners of theaters and film houses. A second console was constructed and installed at Longwood Gardens, Pierre DuPont’s botanical garden and conservatory in Kennett Square, Pennsylvania.

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