158 THE SAN FRANCISCO EARTHQUAKE AND FIRE. 
ACKNOWLEDGMENTS. 
Special acknowledgment is due to the folloAving gentlemen, who 
have courteously aided in the preparation of this paper with informa- 
tion and photographs: T. P. Woodward, city engineer of San Fran- 
cisco; Charles Derleth, jr., associate professor of civil engineering in 
the University of California, and secretary of the Structural Associa- 
tion of San Francisco; A. O. Leuschner, professor of astronomy, 
University of California, and member of the California earthquake 
investigation commission; also Oscar Maurer, O. V. Lange, and 
Willard P. Worden. 
Thanks are also due the Structural Association of San Francisco, 
the California earthquake investigation commission, the American 
Builder's Review and its Engineering Supplement, and the New San 
Francisco Magazine. 
