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CLIMATE DRY AND WET SEASONS. 383 



crops yielded by that mode of cultivation. With irrigation a suc- 

 cession of crops may be produced throughout the year." 



The peculiarities of the climate of California are so well explained 

 in a letter from the Honorable T. Butler King, that we extract 

 his observations thereon as the most valuable portion of the report 

 made by him to the United States Government in March, 1850. 1 



" The north-east winds, in their progress across the continent, 

 towards the Pacific ocean, pass over the snow-capped ridges of the 

 Rocky Mountains and the Sierra Nevada, and are of course depriv- 

 ed of all the moisture which can be extracted from them by the 

 low temperature of that region of eternal snow ; consequently no 

 moisture can be precipitated from them, in the form of dew or rain, 

 in a higher temperature than that to which they have been subject- 

 ed. They pass therefore over the hills and plains of California, 

 where the temperature is very high in summer, in a very dry state ; 

 and so far from being charged with moisture, they absorb, like a 

 sponge, all that the atmosphere and surface of the earth can yield, 

 until both become, apparently, perfectly dry. 



"This process commences when the line of the sun's greatest 

 attraction comes north in summer, bringing with it vast atmospheric 

 movements. Their approach produces the dry season in California, 

 which, governed by these laws, continues until some time after the 

 sun repasses the equator in September, when, about the middle of 

 November, the climate being relieved from these north-east currents 

 of air, the south-west winds set in from the ocean, charged with 

 moisture — the rains commence, and continue to fall, not constantly, 

 as some persons have represented, but with sufficient frequency to 

 designate the period of their continuance, as the wet season, from 

 about the middle of November until the middle of May, in the lati- 

 tude of San Francisco. 



" It follows, as a matter of course, that the dry season commences 

 first, and continues longest in the southern portions of the Territory, 

 and that the climate of the northern part is influenced in a much less 

 degree by the causes which I have mentioned than any other section 

 of the country. Consequently, we find that as low down as latitude 

 39° rains are sufficiently frequent in summer to render irrigation 

 quite unnecessary to the perfect maturity of any crop which is suited 

 to the soil and climate. 



1 See T. B. King's Report on California, Ex. Doc. No. 59, 31 Cong. 1st sess. 



