I have been able to determine with considerable accuracy the period of time at which the shock between eight and nine o’clock on the morning of the ninth took place, at four localities east of the City of San Francisco, in this State; as the shock at that hour seems to have been more generally noticed than those which either preceded or followed it here or elsewhere, though at this city it was much less marked than the shocks at 1h. 33m., 4h. 15m., and 7h., these three latter occurring at those hours of the morning when most persons are sleeping. The shock at 7h., produced a circular motion in the pendulum, the diameter of which was about five inches. The oscillations of the pendulum in all the others were in an easterly and westerly direction. The precise period of time at which the shock took place at San Francisco, between eight and nine o’clock, is determined by the stopping of a time-piece belonging to J. W. Tucker, whose rate of error was three seconds fast. The time at San Diego was furnished by Mr. Cassidy, of the army, and that of the Tejon Reserve is by persons at that post. To private gentlemen at Sacramento and Stockton we are indebted for the time at those places. The accompanying table of latitudes and longitudes of localities named, gives the hour at which the shock took place at each; the difference or elapsed time, from which the velocity was deduced, are the mean times corrected for the places named, the time as given above being taken as the standard at San Francisco. It is proper to state that three minutes four seconds, was the greatest error in time found, and the least was twenty-two seconds: --------------+-------+--------+----------+---------+---------- LOCALITY. | Lat. | Lon. | Time of | Elapsed | Velocity. | | | shock. | Time. | --------------+-------+--------+----------+---------+---------- | ° ´ | ° ´ | h. m. s. | m. s. | miles. San Francisco | 37 48 | 122 25 | 8 13 30 | 0 00 | 0 0 Sacramento | 38 32 | 121 23 | 8 20 00 | 7 30 | 6 6 Stockton | 37 52 | 121 34 | 8 23 00 | 9 30 | 6 5 Tejon | 35 00 | 118 46 | 8 45 00 | 32 30 | 6 0 San Diego | 32 42 | 117 13 | 8 50 00 | 36 30 | 7 0 --------------+-------+--------+----------+---------+---------- The velocity is given in miles per minute, and by dividing the sum of the same by their number, it will be found that the movement of the wave at that time averages a fraction over 6.2 miles per minute.