E S. Holden — Earthquakes in California. 399 



Velocity or projection — „ zrlO'O. 



V 2 

 Intensity = — =126. 



This corresponds approximately to Y-VI on the Rossi-Forel 

 scale, according to the table in this Journal, June, 1888, p. 429, 

 which was derived from Japanese shocks. 



Chabot Observatory : the time of the shock is 3 h. 50 m. 

 plus or minus one-quarter of a minute (W. Irelan, Esq.). It is 

 registered on the duplex seismometer plate as follows. The 

 first motion (of the pen, magnified four times) is 2 mm to the W., 

 then follow several small tremors towards the S.E. The mo- 

 tion of the earth is of course in the reverse directions. — Lick 

 Observatory, 3:51 a. m. : severe shock, lasting several seconds. 

 Strong vertical component (YI to Y1I) observed by E. S. H. 

 Also on L. O. seismometer. — Gilroy, sharp shock : Santa Cruz, 

 heavy, (S. F. Call, Sept. 18).— S. F., 91? Pine street: very 

 slight, no record on seismometer, J. R. J. 



September 23, about 11:30 A. M. — S. F., 917 Pine street : 

 very slight shock, J. R. J. 



October 3, 12:52 p. m.— San Miguel, S. L. O. Co.: light 

 shock, 2 sec. duration, N. to S. (III). Another at same place 

 at 1:02 p. m., quite severe, N. to S., 4 sec. duration, no damage 

 done (VI ?), S. F. Chronicle, Oct. 4. 



October 4, P. M. — Paso Robles : slight shock. — S. F. Report, 

 October 5. 



October 4, 11 P. m. — San Diego.— S. F. Bulletin, October 5. 



October 5, 4h. 41m. 30s. ± 10s. A. M — Chabot Observatory: 

 the shock was sufficient to waken a sound sleeper (YI). On 

 the duplex seismometer plate the trace begins with a tremu- 

 lous motion toward the W., followed by two sharp jerks to the 

 S. The motion of the earth is contrary to the motion of the 

 plate. 



October 23 ? — Lick Observatory : During Mr. Heeler's ab- 

 sence the earthquake instruments were in charge of Mr. Hill. 

 On October 23, at 6 P. M., I noticed that the earthquake instru- 

 ments were in their usual state. I also noted at 9 P. M., October 

 24, that a shock had occurred previously. The clock dial of 

 the earthquake clock is divided to 12 hours (instead of to 24 

 hours as it should have been), and there, is an ambiguity of 12 

 hours in the time of the shock, which is either 



October 23, llh. 42m. p. m., or October 24, llh. 42m. A. M. — 

 The shock was sufficient to start the clock of the Ewing 

 seismograph, but the plate did not move. The duplex 

 seismometer plate shows a tremulous wave in the direction 

 KE. and S.W. 



