. I B AGRICULTURAL SOCIETY. 323 



That there should be a region stretching over eight degrees of latitude 

 north and south, the temperature of which is mild and practically constant, 

 LS phenomenal. For its explanation we must look to the Japan current, 

 which Hows down our coast. This current separates from the equatorial 

 as it leaves the Indian Ocean, flows northwest along the coast of Asia, and, 

 oil' Kamtschatka, divides. One branch is directed north into the Arctic 

 Ocean through Behring Strait. The other flows westward until it reaches 

 Alaska, where it is deflected south, closely embracing the coast lines of 

 Washington Territory, Oregon, and California. 



When the Japan current leaves the Indian Ocean its temperature is ( .)0°. 

 As it flows northward tins temperature decreases. I Ml' the coast of Japan it 

 is but 70°, and, as it goes north, the temperature is further decreased, hut 

 not so rapidly. Off the coast of California it is from 55° to 60°, and it rises 

 but little in its course southward. 



The westerly winds of Summer and the southwesterly winds of Winter 

 bear with them the uniformity of temperature of this large body of water, 

 rendering the temperature of the coast warmer in Winter and cooler in 

 Summer than it would otherwise be. It also equalizes the temperature 

 along the whole coast, giving to Santa Barbara — latitude 34° — almost as 

 cool a climate as has Crescent City, latitude 4"_' . 



These westerly winds are in accordance with the well established law 

 that there are "three distinct belts in each hemisphere, namely: the belt 

 of easterly winds, within the tropics; the belt of westerly, within the tem- 

 perate zone; and the belt of northwesterly, at the north." 



The west winds of Summer are greatly intensified by the heat, incident 

 to the great interior valleys lying east of the Coast Range. The heated air 

 rising from the Shasta, Sacramento, and San Joaquin Valleys, and the 

 sandy plains of Tulare and San Bernardino, leaves a vacuum which the 

 sea breeze rushes in to fill. This breeze is unusually strong wherever there 

 is a gap in the Coast Range leading into any of the great valleys. The 

 topography of the western coast is such as to allow^ no conflicting element 

 which would tend to materially modify this general law of temperature. 



The Rocky Mountains, starting from the northern coast of Alaska, stand 

 as a great barrier, warding off, to a great extent, the cold winds blowing 

 southward. AVere it not for these mountains, which break the force of this 

 polar wind, and the still greater protection afforded by the Cascade and 

 Sierra Nevada Ranges, California would, in all probability, be overwhelmed 

 with some of those terrible blizzards which are of such frequent occurrence 

 in the Western and Northwestern States and Territories. 



DISTRIBUTION OF RAIN. 



The distribution of rain is so anomalous as to be worthy of mention. The 

 general law that the annual rainfall is greatest near the equator and 

 diminishes about two inches for every degree of latitude north is, on this 

 coast, reversed. The annual fall of rain at San Diego averages nine inches, 

 increases to twenty-four at San Francisco, and rises to eighty inches at 

 Crescent City, near the Oregon line, figures that the topography of the coun- 

 try only in part explains. 



The temperature of Southern California is so mild and the Coast Range 

 so leveled, that little influence is exerted on the vapor bearing southwest 

 winds. Northward, the Coast Range rises, causing a greater precipitation 

 of rain, which is intensified when the Coast Range intermingles with and 

 is overtopped by the snow capped Siskiyous. 



North of Cape Mendocino the annual rainfall suddenly rises from thirty- 



