I 



EAETHQUAKES ON THE PACIFIC COA.ST 125 



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

 minus one quarter of a minute (W. Ireland, Esq.). It is regis- 

 tered 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 motion 

 of the earth is of course in the reverse directions. — Lick Obser- 

 vatory, 3.51 a. m.: severe shock, lasting several seconds. Strong 

 vertical component (VI to VII) observed by E. S. H. Also on 

 L. O. seismometer. — Gilroy, sharp shock: Santa Cruz, heavy (8. F. 

 Call, Sept. 18). — S. F., 917 Pine Street: very slight, no recoi'd on 

 seismometer, J. R, J. 

 Santa Cruz Lighthouse. Duration about 3 seconds. A very light 

 shock. (ISIs. kindly furnished by the U. S. Geological Survey.) 



J8SS. September 23; about 11:30 a. m. 



S. F., 917 Pine Street; very slight shock, J. R. J. 



ISSS. 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?), 8. F. Chronicle, Oct. 4. 



1888. October 4; p. m. 



Paso Eobles: slight shock.— S'. F. Report, October 5. 



1888. October 4; 11 p. m. 



San Diego. — 8. F. Bulletin, October 5. 



ISSS. October 5; 4b. 41m. 30s. ± 10s. a. m. 



Chabot observatory: the shock was sufficient to waken a sound 

 sleeper (VI). On the duplex seismometer plate the trace begins 

 with a tremulous 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. 



1888. October 23? 24? 



Lick Observatory: Diiring Mr. Keeler's absence the earthquake in- 

 struments were in charge of Mr. Hill. On October 23, at 6 p. m., 

 I noticed that the earthquake instruments 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 — 



1888. October 23; lib. 42m. p. m., or October 24,11b. 42m. a. m. 



The shock was sufficient to start the clock of the Ewing seismo- 

 graph, but the plate did not move. The duplex seismometer plate 

 shows a tremulous wave in the direction N. E. and S. W. 



