September 29th, 15h. 5m.—A very smart shock of earthquake at San Francisco. This was felt at Petaluma.
December 23d, 20h. 19m.—A smart shock at San Francisco.
1863.
During the year 1863 we have had five earthquakes, and unmarked by any serious event.
January 25th, 2h. 20m.—A severe shock was experienced at San Diego, continuing from five to eight seconds. There was no undulation in this instance, the shock consisting of a series of sharp jars. It was preceded by a profound rumbling sound.
February 1st, 16h. 1m.—A very smart shock at the Mission San Juan, Monterey County. At Gilroys the shock was felt (or another) fifteen minutes later. The latter town is near twelve miles east of the Mission. At both localities the motion was undulatory. The shock was not felt at Monterey, twelve miles west of San Juan.
June.—A smart shock at San Francisco.
July 15th, 10h. 19m.—A smart shock at San Francisco.
August 1st, 11h. 6m.—Two light shocks at San Francisco about one hour apart.
December 19th, 12h. 38m.—A very smart shock was felt throughout the city; directly afterwards another and more severe one occurred. The first was a sharp, sudden jar, the second undulatory. The accuracy of the telegraph operator at Santa Clara enables us to form a correct idea of the course of this wave. His time was 14h. 44m. 31s., and within twenty-nine seconds of true time. The elapsed time is 7m. 31s., and gives for the direction of the seismic wave a course north and south (in lieu of east and west in my first notice which was thus in error.) I take this opportunity to express the thanks of the Academy to this operator for his accuracy and kindness in furnishing us dates in this and other phenomena of scientific and public interest.