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towards the west, and hence the northeast trades in the northern hemisphere and the southeast 

 trades in the southern hemisphere — where the conditions are reversed — but both flowing towards 

 the belt of greatest rarefaction. The particles of air approaching the equator will not ascend in 

 a perpendicular direction, but will rise continually as they advance towards the west along an 

 ascending plane, and will continue for a time their westerly motion in the northern hemisphere. 

 After they have commenced their return towards the north, and until they arrive at parts of 

 the earth moving more rapidly than themselves, the}' will gradually curve towards the east, 

 and finally descend earthward, to become again a part of the surface trade winds from the north- 

 east. The atoms will move westward as they ascend — first, on account of the momentum in 

 that direction ; and, second, because, as they reach a higher elevation, they will have less east- 

 erly velocity than the earth beneatb. They will also be affected by another force, first pointed 

 out by Mr.Ferrell, due to the increase of gravity which a particle of matter experiences in 

 traveling in a direction opposite to that of the rotation of the earth. The last mentioned cause 

 of deflection will operate in an opposite direction on atoms when they assume an easterly course. 

 The result of the complex conditions under which the motive power acts in such a case would 

 be to produce a system of circuits inclined to the west, the eastern portion of which would be at 

 the surface, and the western portion at different elevations, even to the top of the atmosphere. 

 The greater portion of the circulation would descend to the earth within thirty degrees of the 

 equator, giving rise to the trade winds: another portion would flow further north, and produce 

 the southwest winds, and another portion flowing still further north would descend to the earth 

 as a northwest wind. The air which descends in the region of the north pole would not flow 

 directly southward, but. on account of the rotation of the earth, would turn towards the west 

 and become a northeasterly current. It might appear, at first sight, that the north wind which 

 descends from the polar regions would continue its course along the surface until it joined the 

 trade winds within the tropics; but this could not be the case, on account of the much greater 

 western velocity which this wind would acquire from the rapidly increasing rotary motion as 

 we leave the pole. There would, therefore, be three distinct belts in each hemisphere, namely, 

 the belt of easterly winds within the tropics; the belt of westerly, within the temperate zone; 

 and the belt of northwesterly, at the north. 



Without doubt these laws would operate uniformly if the earth 

 were a perfectly smooth sphere, with a uniformly radiating and 

 absorbing surface, but it is broken by mountain chains, covered by 

 large tracts of desert, which rapidly absorb and as rapidly radiate 

 heat; about three-fourths of its surface is water, which slowly absorbs 

 and as slowly gives up its heat; the water of the ocean is in circula- 

 tion, producing great currents, which, in this hemisphere, carry a 

 portion of the heat of the tropics into northern latitudes, and the 

 cold of the north into warmer latitudes. All of these causes inter- 

 rupt the uniformity of the flow of the rereal current, change its tem- 

 perature, and give rise, as well as direction, to local winds. The 

 zones of tropical winds move bodily to and fro with the vertical 

 sun northward during our summer, and southward during our win- 

 ter. The belts of westerly winds in the temperate zone move north 

 and south with these. As California is within the northern temper- 

 ate zone, it is primarily to the movement as a body north and south 

 of this belt of wind that we are indebted for our 



DRY SUMMERS AND WINTER RAINS. 



AVhere, within the tropics, the northeastern and southeastern trade 

 winds meet is a region of calms and rains. This belt of calms and 

 rains, as has been stated, moves northward and southward with the 

 sun's declination. AVhere, within the temperate zone, the northern 

 and northwesterly winds from the polar regions meet the westerly 

 return trade winds, is a region of storms and rains. These belts also 

 follow the sun's declination north and south. Applying these laws 

 to this coast, at our midsummer the vertical sun would be on the 

 tropic of Cancer, and in that vicinity the northeasterly and south- 

 easterly trade winds would meet, create ascending air, consequently 

 calms; this air, laden with moisture, would rise into cooler regions, 

 when a portion of its moisture would be precipitated, making trop- 



