ISOSEISMALS: DISTRIBUTION OF APPARENT INTENSITY. 243 
which was of course in the sand. There were also other blow-holes in the sand, which 
emitted water and sulfurous odors. 
Effect of the shock on the gas plant and pipes (E. C. Jones). — The earthquake movement 
was apparently from north to south, inferred from the fact that bookcases and china 
closets placed east and west were almost invariably tipt over, or their contents thrown 
out; while those placed north and south were in most cases undisturbed. Gas-mains 
in streets running east and west were broken and drawn apart, while those in streets 
running north and south were crusht together and telescoped, or else raised out of the 
ground in inverted V’s. This rule applied generally, with but few exceptions. 
On Jackson Street, between Drumm and Davis Streets, which is made land, the street 
main was laid on a line of piles which went to hard pan. The piles were not purposely 
driven to sustain the pipe, but happened to be in the line of the main when it was laid. 
This pipe broke over the center of each pile, 9 in number, and was not broken in the 
made ground where it was unsupported. 
During the latter part of the first shock, there was a rotating motion which had the 
effect of twisting gas-holders out of their guide frames. 
The foreman of the North Beach Station was looking at the 2,000,000-foot storage 
holder, and described it as follows: 
On going to the window, I lookt at the storage holder, which was vibrating like an in- 
verted pendulum, and waves of water were coming over the wall of the tank. The relief 
holder was similarly affected with water and tar coming over the tank wall. The shrabbery 
in the garden was shaken as tho by a strong wind. 
These two holders were heavily framed with latticed girders, and did not leave their 
guides by the rotating movement of the earthquake. 
The storage holder at the Pacific Gas Improvement Company’s Works was twisted 
around 2 feet from the guide rails, while at Martin Station the 1,500,000-foot storage 
holder was twisted 5 feet on the lower section, 8 feet on the middle section, and 12 feet 
on the upper section. At this plant the 4,000,000-foot generator was moved bodily 
2.5 inches to the south. All connections were of steel, and no joints were broken. 
A barn at the North Beach Station, corner of Laguna and Bay Streets, was resting 
upon wooden uprights about 16 inches high. These uprights were tipt over, and the 
barn moved the length of the uprights toward the south; that is, after the earthquake it 
stood 16 inches on the sidewalk. 
The buildings at the different plants did not suffer according to their relative strength. 
Some brick buildings of comparatively poor construction were unharmed. Other build- 
ings of great strength, with heavy footings on good foundations, were shaken to the 
ground, particularly those running east and west; while buildings of the same or less 
strength, with foundations not so good, but running in a direction north and south, were 
but little injured. 
Effect on certain street railways (T. Mallally). — There does not seem to have been any 
actual shortening of the length of the street railways of the United Railroads of San 
Francisco; but the rails in one location traveled about 3 feet in a northerly direction. 
This location was in the valley and was marsh land, beginning at a point about 100 yards 
north of Holy Cross Cemetery, where the rails parted, and ending about 1,000 yards north 
of Holy Cross, where the rails buckled up in the air. We had to cut out about 3 feet at 
this point, and add 3 feet where it parted at the other end. Of course there was a decided 
movement of the rails all along, in a lateral direction, which left the tracks out of aline- 
ment, but was not enough to prevent operation of cars. 
This condition would indicate that the fill in the marsh land moved in a northerly 
direction about 3 feet, but that the actual distance along our line has not been appre- 
ciably changed. 
