32 ATMOSPHERIC DUST. 



Table XX. Mechanical Composition of some Dust collected in Running Railroad Coaches. 



76 



Length o! 



diameter In 



mm. 



Sandstorm in 

 Arizooa. 



From sonthem From Nebraska From 



MiDne«^ota. and Kansas. Xew England. 



Table TV. sContinuedj. 



80 



81 f 83 1 83 



84 



Frnm N. Dakota 

 and Montana. 



From Rnckr Mtf . From Utah. From N. Dakota, 

 and Ca.=cade Mts. Speed 30 mi. pr h. alt^r a storm. 



From N. Dakota. 



tr. 



3.6 



35.5 



56.8 

 3.9 



^ 



tr. . 



