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in one of its valleys, elevation four hundred and eighty-five feet, 

 from a record of six years, has an annual mean of thirteen and 

 twenty-eight one-hundredths inches, while Ellis, at its northeastern 

 base, with an elevation of seventy-six feet, from a record of six years, 

 receives but an annual mean of nine and twenty-two one-hundredths 

 inches. Benicia, at its northwestern base, elevation sixty-four feet, 

 from a record of thirteen years, receives an annual mean of thirteen 

 and seven one-hundredths inches. This increase at Benicia shows 

 an interference with the law, which, I think, may be explained by 

 the indraught of air into San Pablo Bay from the Bay of San Fran- 

 cisco, through the narrow channel, on the bank of which Benicia is 

 situated. General Myer, Chief of the Signal Service, in his circular 

 on the practical use of meteorological reports, says that " Wind 

 which on the ocean would blow with a certain velocity, will have but 

 one-half or one-third of that velocity when blowing over a hilly 

 country." While Diablo robs Benicia of its rain, it is, in part, com- 

 pensated from the currents of moisture-laden air that flow up the 

 Straits of Carquinez, in consequence of meeting with less resistance. 



The summit of the Sierra Nevada, where it is crossed by the rail- 

 road, as has been shown, receives an annual mean of fifty-eight and 

 forty-eight one-hundredths inches. Boca, thirteen miles northeast 

 in an air line, but one thousand four hundred and eighty-four feet 

 below, on the eastern flank, for the same number of years, receives 

 but an annual mean of fourteen and fifty-eight one-hundredths 

 inches, and Reno, thirty-one miles in an air line in the same direc- 

 tion, and one thousand five hundred and ten feet below the summit, 

 and nearer the eastern base of this range of mountains, receives for 

 the same time but an annual mean of four and seventy-eight one- 

 hundredths inches. There are two stations, one on each side of the 

 Sierra Nevada, whose elevations above the sea are nearly the same, 

 Alta on the southwestern side, and Brown's, on the northeastern — 

 the first has an elevation above the sea of three thousand six hun- 

 dred and twelve feet, the latter of three thousand nine hundred and 

 twenty-five feet. Alta received, during a record of seven years, an 

 annual mean of forty-seven and thirty-two one-hundredths inches, 

 and Brown's, for the same period, three and fifty-three one-hun- 

 dredths inches. Dr. Henry Gibbons has shown from his daily record 

 of the climate of San Francisco that whatever course the wind may 

 have near the surface of the earth at this place, the upper currents 

 of air, whenever their clouds could be seen, were moving from the 

 southwest. The records from the station at the summit of the Sierra 

 show the same fact. It is not unfrequent that the Sacramento Valley 

 is filled with a southeast wind — it may be giving rain — while a cloud 

 bearing southwest wind is blowing at the summit. When this south- 

 east wind becomes a storm, it flows up the canons, ravines, gulches, 

 and river courses as a southwest wind, and joins this upper current, 

 for the general course of all the ravines and river courses of the Sierra 

 is from the northeast to the southwest, and the wind, like other fluids, 

 takes the course of least resistance. 



It is believed that an early fall of snow in the Sierra increases the 

 rainfall in the Sacramento Valley. There is not yet sufficient data 

 to hazard a positive conclusion on the subject. All the moisture 

 bearing winds pass from the valley over this snow into the great 

 basin of Nevada; therefore, an early fall of snow, storing up a cold 

 temperature, would probably increase the subsequent fall on the 



