THE BOTANY OF THE ROUTE. 29 



50. In summer there is little or no difference recorded. In addition to this, the nature of the 

 soil causes the retention of much more moisture near the coast, there being often a very tena- 

 cious clay at or near the surface. Near the mouth of the Columbia there is also much more 

 rain than at a distance of a few miles north or south of it. I have stated that towards the sum- 

 mit of the Cascade range there is also a much greater precipitation of moisture, which is 

 accompanied by the reappearance or greater luxuriance of the trees and other plants of the 

 coast forests, and this is especially well marked in the gap of the Cascades. 



I have already mentioned the difference observed in the temperature both of summer and 

 winter at the Dalles and at Vancouver, which are in nearly the same latitude. By the same 

 records it appears that the mean annual difference between Vancouver and Steilacoom, a hundred 

 miles further north, is exactly 2 degrees, each season being a little cooler at the latter place. 

 The same or a greater difference exists along the coast, but has not been recorded. The effect, 

 however, of these differences on vegetation is scarcely appreciable, and the amount of moisture 

 is by far the most influential. Of cultivated crops no statistics are at hand, but I have observed 

 that in the wet summer of 1854 they did best east of the Coast range; while that of 1855 being 

 much drier, they succeeded best west of it. 



I have alluded to the mildness of the winters, and, in addition to the published records, some 

 notes on its effects in relation to natural history may be interesting. 



At Vancouver, from November 18 to January 4, 1853, the weather was very mild and rainy, 

 though with many bright, warm days. There was often slight frost at night, but vegetation 

 continued, and flowers of several kinds were constantly to be found on the prairie. I thought 

 December pleasanter than the month I had spent there after my arrival in the middle of June, 

 as it was cooler and not much more rainy. 



On January 5 there was a fall of two inches of snow, and the rest of the month was clear and 

 cool for days together, an easterly wind taking the place of the usual winter sea breeze. More 

 snow fell on the 13th, 16th, 20th, and 24th, making in all about 6 inches, which covered the 

 ground for two weeks. By the 26th the Columbia was closed with ice nine inches thick, which 

 broke up on February 10. The thermometer did not fall to zero during the winter, and the 

 lowest I noted was 15°. 



On February 20 I went to the mouth of the Columbia, and remained there and at Shoalwater 

 bay the spring following. On the 25th the native willow and chickweed (Stellaria borealis) 

 were in flower and winter at an end, although there was a light fall of snow afterwards, and 

 spring came slowly. This winter was one of the coldest ever known at Vancouver, where it is 

 rare for the river to freeze at all. Its effect on the migration of birds was marked, as it drove 

 southwards ithe immense flocks of swans, geese, and ducks, which usually make the Columbia 

 their winter resort. A few birds, too, seemed to have crossed from the colder eastern side of 

 the Cascades, (PicicoRVUS,)but the greater part of the land birds, as usual, remained constantly 

 at their summer homes, including more than twenty species. 



The next winter I spent at Shoalwater bay, and made the following notes regarding it: There 

 was white frost first on the 7th of October, and afterwards much clear frosty weather up to 

 the last week in December, with northeast wind, unusual at this season. The last week of the 

 year was marked by a continued and severe storm, not cold, but with heavy rains from the 

 southwest. On December 21 I saw the large, brown salamander still crawling actively about, 

 and the same week noticed a warbler and snipe. 



