EARTHQUAKES ON THE PACIFIC COAST 159 



1891. May 19 s Susan ville. 



Seven shocks felt; two very heavy; time not reported. 



1S91. May 20; San Francisco; lOh. 4m. p. m. 



Light vibration, duration 2s. — T. T. Mills College: Prof. Keep 

 writes: "An earthquake was felt here last night about 10 o'clock. 

 The shock was slight, but was preceded by a peculiar sound 

 which made me brace myself for a severe shock." The seismo- 

 graphic record accompanying this letter shows the greatest dis- 

 turbance to have been in a north and south direction. 



1891. Jnne 22; Pasadena and San Fernando. 



Slight shocks felt between 8 and 9 o'clock in the evening. 



1891. Jnne 28; San Francisco; 3:02:45 a. m. 



Keported in S. F. Chronicle as follows: "A double shock of earth- 

 quake occurred early yesterday morning. It was not heavy, and 

 was of such brief duration that not many of the citizens who 

 were awake at the time could have noted it. F. W. Edmonds, the 

 assistant in Prof. Davidson's observatory, was at work when the 

 shock came and noted its features, afterwards comparing his 

 figures with those recorded by a small seismograph. The first 

 shock began at 3.02.45, Pacific standard time, and ended five sec- 

 onds later. The vibrations were east and west. Then at 3.03.05 

 there was another shock, so brief that the duration was not 

 recorded. It was sharper than the first shake, but had the same 

 naotion. 



Prof. Davidson remarked that one night last week, while he was 

 making observations for latitude, there was an almost imper- 

 ceptible quake. He was reading the level of the instrument at 

 the time and noticed that it was suddenly shaken, the bubble mov- 

 ing backward and forward several times in quick succession. 

 The extremes of this motion as marked by the bubble were three 

 or four millimeters apart. The vibrations were north and south." 



Mount Hamilton: waked sleepers, set hanging lamps in vibration, 

 rattled windows, pictures, stoves, etc. Ewing seismograph clock 

 did not start; components were therefore recorded as straight 

 lines. The actual displacements of the earth [magnified] were 

 as follows: North and south = 0.24 inches; east and west =: 0.39 

 inches; vertical = 0.15 inches. 



Mr. Campbell makes the time 3.02.36 ± 2s.— P. S. T. 



Mr. Schaeberle makes the time 3.02.35 (watch). — P. S. T. 



Intensity on Rossi-Forel scale, V. 



1891. Santa Crnz; June 28; about a a. ni. 



Shock not felt at the lighthouse, two miles from town. (Ms. 

 kindly communicated by U. S. Geological Survey.) 



