122 TABLES AND RESULTS OP THE PRECIPITATION, 



by that for the year, since the latter necessarily brings out the resultant phenomena, 

 and should consequently be of greater complexity than either of those for the 

 extreme seasons. With a few exceptions, presently to be noticed, the distribution 

 of rain in the extreme seasons is not very dissimilar from that of the year as a 

 whole. 



Distribution of Rain in Summer. — The leading feature is the transfer of the 

 maximum rains to the peninsula of Florida. On its western or Gulf coast, we find 

 twenty-eight inches recorded during June, July, and August ; proceeding northerly 

 and easterly, this amount gradually diminishes to less than one-half in Virginia. 

 The peninsula of Florida is subject to the regular rainy season of the tropics, 

 attaining its maximum about one month after the sun's greatest northern declina- 

 tion. There is a fresh development of rain over northern Indiana, northern Illi- 

 nois, northeastern Iowa, and extending as far as central Minnesota, with one of 

 its foci of sixteen inches, directly south of Lake Michigan. This is most probably 

 due to a direct influence of the lake. The region is well traced out by the twelve 

 and fourteen inch curves, the former running up along the western shore of the 

 lake. On the chart, the ten and twelve-inch curves appear quite complex in their 

 windings. 



In California, we have a large area, extending from the Colorado to the Sacra- 

 mento River, where no rain falls during the three summer months ; at most, there 

 may be an occasional sprinkling, often hardly enough to wet the gauge. Even in 

 the most southerly part of the State, we find nothing analogous to the rainy season 

 noticed in similar latitudes in Georgia. This may be explained by the different direc- 

 tions of the wind. On the Atlantic coast, as far up as latitude 32|° north (on the 

 average during the year and still higher in the summer), the (easterly) trade- 

 winds blow constantly ; on the Pacific coast, on the contrary, all along the peninsula 

 of California, and on the coast of California proper, as high north as latitude 41°, 

 the prevailing wind during the year is from the northward and westward. And it is 

 also to be noted that the ocean currents partake of the same difference in direction — 

 the Gulf Stream on the Atlantic side running northerly, and the coast current on 

 the Pacific side running southeasterly; the former being a warm, the latter a cold 

 current. The California current is a branch of the north Pacific easterly current, 

 which divides, off the coast of Oregon, sending one branch towards the coast of 

 Washington and Alaska Territories, and the other skirting the coast of California. 



Distribution of Rain in Winter. — In this season, we find the influx of moisture 

 from the Gulf of Mexico over the Mississippi delta in its full development ; there 

 is a heavy precipitation of rain west of the river, and covering Arkansas and adja- 

 cent parts of Missouri. The current of moisture sweeping over Alabama and 

 Mississippi, after running due north about 250 kilometres, bifurcates. One branch, 

 of sixteen inches rain, skirts the southern and eastern spurs of the Alleghany range, 

 and extends into North Carolina, with twelve inches; its southern boundary is 

 along the extreme region of the trade-winds : the other branch passes along the 

 opposite side of the Alleghany mountains, depositing twenty inches in Alabama, 

 eighteen in Tennessee, sixteen in Kentucky, and twelve near the banks of the 

 Ohio River. 



