05. Luxfer Prism, Luxfer Prism Co.
Luxfer Prism Co., Chicago.
Luxfer Prism, c.1900.
Patented in 1897, the glass prisms displayed a decorative pattern on one side and a corrugated surface on the reverse. They were designed to refract natural sunlight far into the interiors of the large office buildings, reducing the need for artificial lighting. Its advantages were cost savings on electricity, more even and better lighting than electric lights, privacy for those inside the building, and a decorative screen to hide unpleasant views of the exterior.

"Burnham Library Centennial," Case 3, Ryerson & Burnham Libraries, September 25-December 3, 2012
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