DUST AND SAND STORMS IN THE WEST. 



66 1 



sible that the stifling sensations felt in a dust-laden atmosphere 

 are the results of a cumulative stimulus on the nervous system, 

 and a smaller quantity might produce similar effects. No doubt 

 there is also a subjective factor which will modify estimates on 

 this line. 



Lastly, an estimate, or rather a measurement, has been made 

 on the quantity of sand carried in such storms as are recounted 

 in the following items : " The sand is blown about in such quan- 

 tities that it is not possible to keep one's eyes open." " A man 

 venturing into a whirlwind of sand invariably returned in a few 

 minutes with his face bleeding with hundreds of cuts." " Clouds 

 of sand were driven through the air by a high wind, obscuring 

 all objects and rendering existence almost impossible (sic) for 

 man and beast." 



In 188G the writer had the opportunity to be in the midst of 

 such flying sand on the Western plains, and to make some obser- 

 vations on the quantity borne by the air. The storm was not as 

 severe as those described in the above paragraphs, nor did it carry 

 as much drift, for neither was the author's facial integument 

 punctured nor did he experience any apprehensions as to the pos- 

 sibility of continued existence. But there was enough of sand in 

 the air to deposit one ninth of an ounce during fifteen minutes in 

 a vial with an aperture measuring one tenth of a square inch 

 turned to the windward. A velocity of twenty miles per hour 

 was probably not exceeded where the receptacle was placed, and 

 this would make the load carried equal to nearly thirty thousand 

 tons per cubic mile. 



To sum up : The estimated loads of sand and dust that may be 

 carried by the atmosphere range from 150 to 126,000 tons per 

 cubic mile of air, or from 0'0009 to 077 grammes per cubic foot. 



Summary of Estimates. 



Estimate on a thick haze 



Lowest estimate from accumulation in dwellings 



Estimate on opaque dust clouds 



Estimate on forming sand drifts 



Estimate from effect of dust in the air on breathing. . 

 Estimate from a quantity of sand collected in a storm 

 Highest estimate from a quantity of sand in dwellings 



No. of 

 grammes per 

 cubic metre. 



0-031 

 0-048 

 0-434 

 1-30 

 4-34 

 6-49 

 27-29 



With these figures and the data on the duration and on the 

 frequency of sand storms in the western part of the United States, 

 it seems possible to form some idea of the total amount of work 

 Performed by such storms over this territory. It is not believed 

 that the data presented justify any great claims for exactness 



