"I have been kindly furnished, by Surgeon-General Lawson, U.S. Army, with thermometrical observations, taken at the following places in California, viz: At San Francisco, by Assistant-Surgeon W. C. Parker, for six months, embracing the last quarter of 1847 and the first quarter of 1848. The monthly mean temperature was as follows: October, 57°; November, 49°; December, 50°; January, 49°; February, 50°; March, 51°. "At Monterey, in latitude 36° 38' north and longitude 121° west, on the coast, about one degree and a half south of San Francisco, by Assistant-Surgeon W. S. King, for seven months, from May to November inclusive. The monthly mean temperature was: May, 56°; June, 59°; July, 62°; August, 59°; September, 58°; October, 60°; November, 56°. "At Los Angeles, latitude 34° 7', longitude west 118° 7', by Assistant-Surgeon John S. Griffin, for ten months, from June, 1847, to March, 1848, inclusive. The monthly mean temperature was: June, 73°; July, 74°; August, 75°; September, 75°; October, 69°; November, 59°; December, 60°; January, 58°; February, 55°; March, 58°. This place is about forty miles from the coast. "At San Diego, latitude 32° 45', longitude west 117° 11', by Assistant-Surgeon J. D. Summers, for the following three months of 1849, viz: July, monthly mean temperature, 73°; August 75°; September, 70°. "At Suttersville, on the Sacramento River, latitude 38° 32' north, longitude west 121° 34', by Assistant-Surgeon R. Murray, for the following months of 1849: July, monthly mean temperature, 73°; August, 70°; September, 65°; October, 65°. "These observations show a remarkably high temperature at San Francisco during the six months from October to March inclusive; a variation of only eight degrees in the monthly mean, and a mean temperature for the six months of 51 degrees. "At Monterey, we find the mean monthly temperature of the seven months to have been 58°. If we take the three summer months, the mean heat was 60°. The mean of the three winter months was a little over 49°; showing a mean difference, on that part of the coast, of only 11° between summer and winter. "The mean temperature of San Francisco, for the three winter months, was precisely the same as at Monterey--a little over 49°. "As these cities are only one degree and a half distant from each other, and both situated near the ocean, the temperature at both, in summer, may very reasonably be supposed to be as nearly similar as the thermometer shows it to be in winter. "The mean temperature of July, August, and September, at San Diego, only 3° 53' south of Monterey, was 72°. The mean temperature of the same months at Monterey was a little over 59°; showing a mean difference of 13°. "This would seem to indicate that the cold ocean current is thrown off from the southern part of the coast by Point Conception, and the islands south of it; and consequently its influence on the climate of San Diego is much less than at Monterey and San Francisco.