ACADEMY OF NATURAL SCIENCES. 



139 



The meteorological condition of the atmosphere was rather unusual, and is 

 described as follows : The day was unusually warm and sultry, attended with a 

 little rain, (the latter very unusual) and a sudden change of temperature to 

 unpleasant colduess. At Point San Juan there was observed considerable com- 

 motion in the water, attended with a strong rushing sound, and two unusually 

 heavy surf swells, immediately following the last shock. 



This shock was felt distinctly at the saw-mill, some eight miles east of San 

 Bernardino, about seventy miles east of Los Angeles, and at Santa Barbara, 

 about one hundred miles in a westerly direction. 

 Aug 12th, 9h. 30m. — A light shock of an earthquake was felt at Georgetown, 



which lasted about three seconds. The vibration apparently came from the 



north. Between this date and the tenth July there were four other light 



shocks, the dates of which are not recorded. 

 Oct. 21st, 19h. 45m. — A smart shock of an earthquake was felt in San Fran- 

 cisco. The buildings situated over the water were violently shaken. There 



was much commotion in the water of the harbor a few minutes preceding the 



shock, which caused several vessels to heave heavily at their hawsers and 



cables. 

 Oct 27th, 15h. — A light shock was felt in the valley of Clear Lake. On the 



same day a shock was felt at Downieville, which lasted about five seconds. 



At Goodyear's Bar it was more severe than at the preceding locality. 

 Dec. 5th, llh. 20m. — The shock of an earthquake was felt at Humboldt Bay, 



which lasted about three seconds. There were two vibrations, the last being 



the most severe. 

 Dec. 11th, 4h. — A shock was felt in San Francisco and at the Mission Dolores ; 



at the latter place it is represented as being quite severe. 



The whole number of which I have a record for 1855, amounts to twelve 

 only ; but there may be others which have escaped my notice on account of 

 absence from the city. 



The following table will show the number of shocks for each year, and each 

 month of the year, for six years from 1850 to 1855, inclusive. 



January,... 

 February, . 



March, 



April, 



May, 



Juue, 



July, 



August, 



September, . 

 October, . . . 

 November, . 

 December, . 



Total each year, . 



No. for each 



month in six 



years. 



5 



2 



4 

 4 

 6 

 5 

 3 

 2 

 3 

 6 

 13 

 8 



59 59 



From the above it will be seen that of the total number of shocks in six 



