128 EARTHQUAKES ON THE PACIFIC COAST 



putation we may assume from the record of the north and south 

 component : 



Double amplitude mag"nified ?>.?> times = 0.5 mm. 

 a zzz 0.08 mm. 

 T =z 0:3 seconds. 



_ 2-a _ ^ _ '^'- _ . . 



T ■ ■ a ' '■ 



This corresponds to about II on the R.-F. scale according- to the 

 paper cited above. The intensity was, however, IV or higher. 



EARTHQUAKES ON THE PACIFIC COAST, 1889. 

 1889. Jannary 19; 1:43 a. m. 



Oakland: A slight shock recorded on the seismograj)h of F. G. 

 Blinn (II). 



18S9. January 23; 7:51:58 p. m. (?) 



Mount Hamilton: a very light shock suspected by C. B. Hill (IV). 

 No record was found on the seismographs. 



1889. Febrnary 6; 9:20 p. m. 



Southern California: a distinct shock at 9.25 p. m., shaking- build- 

 ings and causing people to run into the streets. Vibrations from 

 north to south, lasting about ten seconds (VI). San Bernardino 

 papers. Colton: Two distinct shocks at 9.20 p. m. Los An- 

 geles: slight shock at 9.25 p. m. Shock accompanied by distinct 

 dull rumbling. Post office clock at San Bernardino stopped at 

 9.20.30, subject to an error of five or six seconds (VI). The 

 clock faced the east. W. C. Parmley, San Bernardino. At 

 Kodiac Island earthquake waves were recorded from February 5, 

 9 p. m., to February G, 7 a. m. 



1889. March IG; 2 p. m. 



Point No Point Lighthouse, Washington. A slight shock. — U. S. 

 L. H. Board. 



1889. April 3; 2:39 a. m. 



Mount Hamilton: a slight record was made on the Ewing and 

 duplex pendulum seismographs (II). The greatest motion was 

 from north to south, a very slight motion from east to west, and 

 the vertical component was imperceptible. The maximum (mag- 

 nified) amplitude was about one-fourth millimeter, and the period 

 of a vibration about two-thirds of a second; hence the com- 

 puted intensity is 7.0 or (I) by the Rossi-Forel scale. This shock 

 was not felt by anybody at the observatory. The time given is 

 that recorded by the seismograph clock. 



