View of air filter for air circulation system in basement, Main Library, Detroit Public Library. Sign on door on right: "Close this door." Handwritten on front: "Elev. 144.03, col #112, EA/3, Stage 2A, G+K #153." Printed on front: "Detroit Library Commission. Addns. & alts. to Main Public Library. F.H. Martin Construction Company. Descr. basement, existing building, to be the auditorium lobby, IIA. No. 92. Date: 2-7-61. Win Brunner, photo."
