U. S. GEOLOGICAL SURVE/ 
BULLETIN NO. 324 PL. 
' * « W^4. 
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A. AN UNFINISHED STEEL SKELETON, WITH NONFIREPROOFED STEEL WORK. 
; - ;.*- 
]!. UNPROTECTED STEEL FRAME AND GENERAL FLIMSY CONSTRUCTION. COWELL BUILDING. 
EFFECTS OF HEAT ON STEEL WORK, SAN FRANCISCO. 
Photographs by Richard L. Humphrey. 
