136 THE POPULAR SCIENCE MONTHLY 



rence of a heavy dew near tlie Falls of the Missouri is attributed to 

 the greater damj^ness of the air in that place resulting from the spray 

 produced by the falls. This reminds one of the reported appearance 

 of dews in the vicinity of desert oases, and of the tradition that travelers 

 across deserts have often been assured of their approach to an oasis 

 when they have observed that dew forms at night. The frequent firing 

 of the grass on the Great Plains by the Indians is often referred to, but 

 there is no reference to the possible effects of this custom upon the 

 treelessness of the region. 



The winter time which was spent by the Lewis and Clark Expedi- 

 tion on the Pacific coast, at the mouth of the Columbia Eiver, gave 

 Captain Lewis abundant opportunity to observe the meteorological 

 and climatic peculiarities of that region, and to contrast them with 

 those with which he had become familiar in the east. " The loss of 

 my thermometer I most sincerely regret," he wrote on January 3, 1806. 

 " I am confident that the climate here is much warmer than in the 

 same parallel of latitude on the Atlantic Ocean, though how many 

 degrees it is now out of my power to determine." A few days later 

 we read, " Weather perfectly temperate. I never experienced a winter 

 so warm as the present has been," and note is made of the fact that the 

 Coast Indians wore, and needed, less clothing than those east of the 

 mountains. Clouds, and heavy rains and gales — much changeable 

 stormy weather and very little sunshine — made such an impression that 

 Captain Lewis wrote, " The vicissitudes of the weather happen two, 

 three or more times in half a day." The early part of the winter was 

 so mild that, as already noted, it could not fail to attract attention for 

 that reason. There being no ice, meat was smoked in order to save it, 

 and even that method was by no means uniformly successful. Later 

 on, however, we find frequent mention of greater cold, of snow and of 

 "hail" (frozen rain?). On January 28, 1806, a vessel of water was 

 exposed in order that the thickness of ice might be measured. Unfor- 

 tunately, the Avater was only two inches deep, and it froze to the bottom. 

 " How much more it might have frozen had the vessel been deeper is 

 therefore out of my power to decide," was Captain Lewis's interesting 

 and critical comment. It is clearly stated that the winds from the land 

 were cold and clear, while those obliquely along the coast or off the 

 ocean brought warm, damp, cloudy and rainy weather. Thus a signifi- 

 cant climatic control received early and explicit recognition. Later in 

 the winter (March 6) this earlier statement was qualified as follows: 

 " Easterly winds which have heretofore given us the only fair weather 

 we have enjoyed seem now to have lost their influence in this respect." 

 The strongest winds came from the southwest. There is further an 

 interesting statement to the effect that a certain harbor was not protected 



