ISOSEISMALS: DISTRIBUTION OF APPARENT INTENSITY. 209 
Angel Island Light Station (Mrs. J. E. Nichols). — The shock resembled the jolting of 
a railway train which, running at full speed, had left the tracks and was bumping over 
the ties. It was accompanied from the beginning by a loud noise which gradually de- 
creased as the jolting motion ceased. Water standing in a pail was thrown out 6 feet 
from northeast to southwest. The clock was stopt. The bay was calm. A cement 
pavement was cracked to pieces. The station is on solid rock. 
Yerba Buena Island Naval Training Station (Capt. A. T. Marix). — A heavy vibratory 
shock was felt. 
Alcatraz Island. — A heavy shock was felt in which there were 3 maxima, the middle 
being the strongest. Objects were overturned in every direction. 
Southeast Farallon Island (James A. Boyle, assistant observer of the U. 8. Weather 
Bureau). — The ground is composed almost entirely of solid rock. The Weather Bureau 
building is on a narrow neck, 15 feet above sea-level, between 2 peaks about 300 feet 
high. Objects in this building were thrown east. A stone weighing about 100 pounds 
slid 6 inches west by south, and was turned slightly counterclockwise. There was no 
rotary nor vertical motion felt. There were 2 maxima, of which the first was the stronger, 
and the motion was east and west in both cases. ‘The only damage done was the opening 
of a crack across the entire front of the fireplace. ‘Two rock slides, of about 100 tons 
each, occurred on the west end of the island. At 10° 06" a. m., April 18, two distinct 
vibrations were felt. They were also felt by Mr. Legler, of the Weather Bureau Station 
at Point Reyes Light-house, with whom Mr. Boyle was talking over the telephone at the 
time, 3 seconds before they were felt on the island. 
SONOMA VALLEY. 
In the Sonoma Valley Mr. E. S. Larsen made the following observations: 
Melita. — Chimneys are all down and plaster somewhat broken. Shock somewhat 
less than at Santa Rosa. 
Between Melita and Kenwood conditions were about the same. Nearly all chimneys 
were thrown down or twisted. 
Kenwood. — Most of the chimneys were down. The brick hotel was not much injured, 
but a few poorly constructed 1-story stone buildings were somewhat damaged. 
Glen Ellen. — Chimneys were nearly all down. Popp’s poorly constructed 2-story 
stone building was damaged so that the upper story had to be torn down. One wall 
of a brick building whose braces had been removed to make room for a stairway was 
much cracked. The other walls were little damaged. A clock with a half-second pen- 
dulum, facing south, stopt at 5" 13". A fireman and an engineer on the San Fran- 
cisco and Northwestern Railroad say that the shock started at exactly 5" 13", 
Eldridge, State Home. — All chimneys were thrown down and the upper story of each 
of the 3-story brick buildings was so damaged that it had to be removed. In a few 
cases there were cracks in the lower stories. One large electric clock with a second pen- 
dulum, facing northeast, stopt. Another clock with a half-second pendulum, facing 
southwest, did not stop, but its pendulum was turned about 20° clockwise. 
Aqua Caliente. — Most of the chimneys were thrown down and the plaster was cracked. 
There was little damage to the brick and adobe houses. 
Boyes Hot Springs. — An artesian well 97 feet deep now yields a larger stream. 
El Verano. — Nearly all chimneys were down. A clock with a half-second pendulum 
and facing east stopt at 5° 15". 
Sonoma. Population 650.— Chimneys were nearly all down. Some of the brick 
and adobe buildings were damaged, but the shock was much less severe than at Santa 
Rosa. At the Hillside Cemetery, 0.125 mile east of the railroad depot, out of about 18 
tombstones over 4 feet high and having the usual square or round section, 13 were 
i ve! 
