t902. 



FORESTRY AND IRRIGATION. 



423 



climate in the lake region are ground- 

 less 



Returning now to the subject from 

 which this digression has been made, I 

 would remark that the influence of the 

 Great Lakes on the climate of the white 

 pine belt is largely thermal and is no- 

 ticeable at all seasons. Consider for a 

 moment the cycle of changes that the 

 water undergoes each year. It reaches 

 its highest temperature on Lake Supe- 

 rior, for example, in September, more 

 than two months after the summer sol- 

 stice. With the advent of cool weather 

 in the autumn the surface film of water 

 becomes chilled and sinks and warmer 

 water rises to take its place. This pro- 

 cess continues until the great mass of 

 the upper layers of the water become 

 cooled to about 39 . Ice does not begin 

 to form until the first of January, and 

 then along the shores only, the middle 

 of the lake remaining open the entire 

 winter. The air near the surface of the 

 lake waters must therefore always be 

 warmer than to the westward and north- 

 ward, over the cold, frozen land surfaces, 

 and this warmer air is carried eastward 

 and southeastward by the prevailing 

 winds, thus tempering the climate of 

 those regions. In summer, while the 

 soil is rapidl}' warming under the influ- 

 ence of solar radiation, the lake waters 



are responding much more slowly to 

 the increased insolation, so that it fre- 

 quentl}' happens that the air and water 

 temperatures are as much as 20 apart. 

 The cooling effect of the lakes is felt far 

 to the eastward and the advent of spring 

 is thus delayed, since more time is re- 

 quired to heat the great mass of water 

 within the lake region than the land 

 surfaces to the west and southwest. 



The development of the White Pine 

 within the region of its occurrence can 

 scarcely be attributed to the influence 

 of climate alone, since it is occasionally 

 absent from considerable areas within 

 its own particular climatic zone ; nei- 

 ther does it seem possible to correlate 

 its growth and development with a sin- 

 gle climatic element. It seems more 

 probable that it should be ascribed to a 

 fortunate combination of soil and cli- 

 mate, the dominating characteristics 

 of the latter being somewhat as fol- 

 lows : First, an atmosphere containing 

 a high percentage of moisture, with 

 much cloudiness and, conversely, little 

 bright sunshine ; second, frequent small 

 rains and snows, uniformly distributed 

 throughout the year (about one-fourth 

 of the precipitation is in the form of 

 snow); and, third, relatively low tem- 

 perature, absence of hot winds, and pro- 

 longed periods of high temperature. 



SEPTEMBER FOREST FIRES. 



GREAT LOSS OF LIFE AND PROPERTY IN OREGON AND 



WASHINGTON. 



THERE were unusually destructive 

 forest fires in several of the far 

 western states during September. The 

 fires in Oregon and Washington were 

 the worst in many years, while in Colo- 

 rado, Wyoming, and Montana an im- 

 mense amount of timber was destroyed. 

 "Washington. On September i r for- 

 est fires broke out in a number of places 

 in Mason, Thurston, Chehalis, and 

 Lewis counties. The towns of Elma, 

 Folsom, Shelton, Mattock, Black Hills, 

 Bucoda, Rainier, and Castle Rock were 

 all threatened by the flames. 



The fire was worst on the North fork 

 of Lewis river, where 16 lives were lost, 

 32 families lost their homes, and $1 ,000, 

 000 worth of timber was destroyed. 

 Forty persons were saved by reaching 

 an open space in the forest known as 

 Speleyah Prairie. The Lewis River 

 fire occurred within thirty miles of 

 Portland, Oregon. 



In Cowlitz county 140 sections of 

 timber, valued at $1 ,000,000, was burned 

 over. In the Rock Creek district, 

 Clark county, the fires burned over 

 large areas, and .several lives are re- 



