PREFACE. 
By Joseph A. Holmes. 
Immediately after the San Francisco earthquake and fire of April 
18, 1906, it was decided to arrange for an investigation of their effects 
on buildings and materials of construction. Accordingly, on April 
19 Richard L. Humphrey was sent to San Francisco for this pur- 
pose, as secretary of the National Advisory Board on Fuels and Struc- 
tural Materials and representing the structural materials division 
of the United States Geological Survey. At the request of the Presi- 
dent, Capt. John Stephen Sewell, Corps of Engineers, United States 
Army, was sent to San Francisco on a similar errand by the War De- 
partment under order of April 23, 1906. Frank Soule, dean of the 
college of civil engineering of the University of California, was asked 
late in the fall of 1906 to prepare a report on the general earthquake 
and fire conditions. G. K. Gilbert, of the United States Geological 
Survey, also a member of the California earthquake investigation 
commission, who was near San Francisco at the time of the disaster, 
was asked to prepare a brief special report on the phenomena of the 
earthquake. 
Mr. Gilbert has brought into his paper only the salient features 
and results of the earthquake, for the reason that the subject is being 
treated more fully in the report of the California earthquake inves- 
tigation commission. 
Mr. Humphrey, who during the last two years has had charge of 
the structural materials laboratories of the United States Geological 
Survey, has had many years' experience in the investigation of struc- 
tural materials, especially with regard to their fire-resisting qualities. 
Before going to San Francisco Captain Sewell had studied care- 
fully the effects of fire on buildings and materials, especially as indi- 
cated by the results of the conflagration at Baltimore in 1904. 
Professor Soule has had the advantage not only of a large experi- 
ence, but also of being thoroughly familiar with the conditions in 
San Francisco prior to the earthquake and fire, and of being on the 
ground during their occurrence. He has had subsequently every 
opportunity for studying, at first hand and in great detail, the effects 
of both the earthquake and the fire. 
