82 DUST STORM. 



immediately changed to the south and in u short time to 

 the south west, the snow still falling. \\'hen it beeanu^ light 

 the snow seemed brown, and upon examination was found 

 to contain dust or ashes giving it the peculiar brown color. 

 It continued in this way until about eight o'clock during 

 which time about three inches fell ; when the snow ceased, 

 the wind changed to the west and the clouds became bro- 

 ken with squalls of clear snow until 6 p. m. when the wind 

 was north-west, the sky cloudless and the cold rapidly in- 

 creasing. At 10 r. M. the thermometer was at 14°, the 

 same as it was at that time the day l)ctore. The highest 

 temperature reached was about 10 a. m. when it was real- 

 ly thawing with the thermometer at 37°. 



I am fully aware that dust storms in many sections are 

 of common occurrance, but not so in this vicinity. They 

 are frecjuently the result of burning forests as there is then 

 carried up in the smoke a large amount of dust from the 

 consuming vegetation, and I am aware that in the Ignited 

 States at least nine-tenths of all dust storms are attribut- 

 al)le to this cause. In all instances however where exami- 

 nation has been made such dust would reveal under the mi- 

 croscope the existance of vegetable ashes and minute Avoody 

 fibre. 1 am informed by Prof. 8. F. liaird, Assistant 

 Secretary of the Smithsonian Institution that repeatedly 

 samples of such dust from snow have been sent to them 

 and in almost every instance the microscope would show 

 in it the result of burning forests or vegetation. 



Durins the summer of 1868 when immense fires were 

 raging in the forests of Washington Territory the whole 

 Pacitic coast was clouded in smoke and such dust storms 

 as before referred to were frequent over a large extent of 

 territory. In these showers the microscope invaria])ly 

 showed vegetable fibre and left no doubt of their origin. 

 Xear large tracts of arid desert, like Sahara in Africa, dust 

 storms are frequent, and of course are the fine particles of 

 sand taken up by the wind and the finer portions are fre- 

 quently borne to great distances. Such showers are fre- 

 quently observed on the west coast of Africa sometimes 



