EARTHQUAKES ON THE PACIFIC COAST 157 



1891. Boulder Creek, January 2. 



A severe shock was felt here at 12 o'clock, continuing- for several 

 seconds. The vibration was from southwest to northeast. There 

 was a general rush for the streets, but no damage was done 

 (VII). 



1891. Spanislitown, January 2. 



A severe shock occurred at three miniites before noon to-day. The 

 vibrations were from east to west. 



1891. jHerce»l, January 2. 



A slight shock was felt here at 12 o'clock to-day with vibrations 

 from east to west. The shake was heavy enough to cause the 

 glassware on the shelves to rattle (VI?). 



1891. RediTOod City, January 2. 



Two sharp shocks were felt here to-day at two minutes past noon. 

 The vibrations were east and w^est. — 8. F. Examiner. 



Seismographic records obtained at Mills College by Prof. Keep and 

 at Oakland by Mr. Blinn show^ the greatest disturbance to be in 

 a direction running from northeast to southwest. 



Mr. Blinn's seismometer gives a diagram indicating that the maxi- 

 mum double amplitude of the pendulum was 3.8 mm. The dia- 

 gram consists of many (not less than 25) intersecting loops. So 

 far as one may judge from the tracing, the instrument was in 

 good adjustment. 



Prof. Keep's tracing is of the same general character, but with a 

 maximum double amplitude of 5.8 mm. 



The Carson City seismometer (C. W. Friend) gives a tracing even 

 more complicated than either of the preceding; it is the smallest 

 of the three, but every azimuth is filled with fine lines. The glass 

 plate of the San Jose instrument was jarred by the earthquake 

 and the record spoiled. 



A third shock of intensity (III) on Eossi-Forel scale is reported by 

 Prof. Holden as occurring at the Lick Observatory at S.18.21 p. m. 



1891. January 13; Berkeley; 1:30 a. ni. 



Prof. Hilgard reports a " light earth-tremor lasting a little less than 

 a second, but preceded by a marked rumbling from the south- 

 west." (Qu.?, a. m.?) 



1891. January 13; Mount Hamilton; 2:58 p. m. 



I to II Eossi-Forel scale; observed by Mrs. Breseno. 



1S91. February 15; Do^vnieville. 



Quite a shock felt between 2 and 3 a. m. 



1891. January 21; San Francisco; 2:24:35^ p. ni. 



Artificial earthquake, caused by the explosion of 3,000 pounds of 

 blasting powder for the purpose of clearing away a hill in San 



