136 HISTORY OF CALIFORNIA. 



on the labor applied to agriculture and the products 

 of the soil, and, in fact, connect themselves so insepa 

 rably with all the interests of the country, that I deem 

 it proper briefly to mention the causes which produce 

 these changes, and which, it will be seen, as this report 

 proceeds, must exercise a controlling influence on the 

 commercial prosperity and resources of the country. 



"It is a well-established theory, that the currents 

 of air under which the earth passes in its diurnal 

 revolutions, follow the line of the sun's greatest attrac 

 tion. These currents of air are drawn towards this 

 line from great distances on each side of it ; and, as 

 the earth revolves from west to east, they blow from, 

 north-east and south-east, meeting, and, of course, 

 causing a calm, on the line. 



" Thus, when the sun is directly, in common par 

 lance, over the equator, in the month of March, these 

 currents of air blow from some distance north of the 

 Tropic of Cancer, and south of the Tropic of Capri 

 corn, in an oblique direction towards this line of the 

 sun's greatest attraction, and forming what are known 

 as the north-east and south-east trade winds. 



" As the earth, in its path round the sun, gradually 

 brings the line of attraction north, in summer, these 

 currents of air are carried with it ; so that about the 

 middle of May the current from the north-east has 

 extended as far as the 38th or 39th degree of north 

 latitude, and by the twentieth of JUDO, the period of 

 the sun's greatest northern inclination, to the northern 

 portions of California and the southern section of 

 Oregon. 



" Those north-east winds, in their progress across 

 the continent, towards the Pacific Ocean, pass over 

 the snow-capped ridges of the Kocky Mountains and 



