370 TRANSACTIONS OF THE 



Nevada, to an elevation of two thousand or two thousand five hundred 

 feet, have like therniometric conditions with the valley. But it is found 

 that the rainfall varies much more than the temperature, and, speaking 

 generally, increases as each degree of latitude is gained, and with each 

 one hundred feet of elevation. 



The junction of the Coast Range and the Sierra Nevada, at the lower end 

 of the great valley, form a transverse partition of the State, on the south- 

 ern side of which lies what is known as Southern California, embraced in 

 the Counties of Los Angeles, San Bernardino, and San Diego. Ventura 

 and Santa Barbara Counties, on the coast and west of Los Angeles, are 

 also usually included in the designation " Southern California." A glance 

 at the map will show that these five counties, taken together, form but a 

 relative small portion of the State. The great agricultural and horticult- 

 ural region of California is the vast valley of the interior, with its two 

 broad belts of foothills, where the skies are brighter than in the coast 

 counties, and where there is entire freedom from sea fogs that are common 

 at San Diego, Los Angeles, and Santa Barbara. The better portion of the 

 State undoubtedly lies north of a line drawn from east to west, midway 

 between the southern and northern boundaries. The soil in the northern 

 portion of the interior basin is fertile, and the rainfall so abundant that 

 both farmers and fruit growers can dispense with irrigation, and the climate 

 is unsurpassed in the world, suited to the production of every variety of 

 deciduous as well as citrus fruits. 



The study of lines of equal heat (or isothermal lines, as they are called,) 

 is of much interest, particularly to persons seeking homes in Califor- 

 nia. In no other way can the climatic peculiarities of our State be so 

 well represented as by maps exhibiting its isothermal lines. Such maps 

 are contained in the Government reports on the Tenth Census of the 

 United States, made in 1880. An examination of the Pacific Coast por- 

 tions of these maps shows that the lines of equal heat run north and south, 

 rather than east and west. In order to present incontestable evidence of 

 the semi-tropical climate of the Sacramento Valley and its foothills, the 

 Bee has had prepared the series of maps accompanying this article, which 

 are faithful reproductions of those contained in the Tenth Census. The 

 data from which the Government plates were drawn were mainly obtained 

 from the Smithsonian Institute at Washington, and are of unquestioned 

 reliability. The first of those here presented shows the mean (that is to 

 say, the average,) rainfall of the various regions of the State. 



The figures on the map, No. 1, stand for mean annual rainfall in inches, 

 and the curved lines in which they are embraced define the areas of equal 

 rainfall. It will be noted that the region tributary to Los Angeles is 

 " semi-aried," its annual rainfall falling below ten inches. That of the San 

 Joaquin Valley ranges from ten to fifteen to fifteen to twenty, while in the 

 Sacramento Valley the range is from fifteen to twenty to twenty-five to 

 thirty. When it is remembered that, with this ample rainfall in Northern 

 California, the region yet enjoys a much greater number of clear days 

 annually than does Los Angeles, the superiority of the Sacramento climate 

 will be better understood. 



