J. Scott Williams of New York designed these printers' marks, and they were installed by the Henderson Brothers from 1925 to 1927. Each of the twenty-seven, 8-by-16 foot windows represents the mark of a prominent Renaissance printer. You can read more about the printers' marks here: http://www.library.uiuc.edu/rex/window.htm. They are located in the Reference Library in 200 Library.
University of Illinois at Urbana-Champaign