Photoelectric relay. Aluminum box with hinged lid. Drill-press decorations. Box houses variable resistors, batteries, knobs and switches. Used with photoelectric cells G-34b and G-34c. Part of Arcturus display at 1933 World's Fair.
ISBN
This photoelectric relay was part of the actual equipment used to light the Century of Progress Exposition in 1933-1934. The two photoelectric cells were part of an exhibition at the Adler Planetarium, used to explain how the light from the star Arcturus was converted into an electrical signal for that purpose.
Material
"Photoelectric relay for opening the 'Century of Progress Exposition' Chicago, May 27, 1933 with light of Arcturus. Made at Yerkes Observatory Williams Bay, Wisconsin with the cooperation of the General Electric Co."
