Observations on Dirtstonns. — Hershey. 381 
the horizon. A strong wind began to blow from the west, 
and shortly after the peculiar brown haze was observed in the 
atmosphere. This gradually thickened as the afternoon ad- 
vanced and culminated at 4:30 p. m. At this time objects one 
mile distant were scarcely visible, and the sun was as complete- 
ly obscured as though hidden by the ordinary vapor clouds. 
Yet during the afternoon not a single true cloud passed over 
this district, as could be readily determined by looking up- 
ward, when the blue sky was discernible, though faintly so. 
An impalpable dust of dark brown color settled on the snow 
and collected behind wind-breaks on its surface, so as to com- 
pletely bury it from sight in places. The impression made on 
the senses of taste and smell was identical with that experienced 
in an ordinary summer dust storm. The precipitation of dust 
continued during the night and the dirt haze was visible the 
next day until evening. During the 30 hours in which the 
precipitation of dirt continued, no snow fell at Freeport, and 
the absence of the ordinary aqueous clouds was especially char- 
acteristic of this time. On the second day the wind had veered 
to the northwest, and the amount of dust decreased, being 
brought in a more roundabout way than the preceding day. 
There are several facts which bear strongly on the manner 
in which this fine soil material was carried in the atmosphere. 
The stratum of the atmosphere containing the dirt was confined 
to a close proximity to the earth. The density of the haze was 
greatest in the lower 500 feet of the air and decreased rapidly 
upward. The blueness of the sky could nearly always be de- 
tected by looking upward, yet objects on the earth one mile 
distant were barely visible. Several thousand feet was proba- 
bly the maximum thickness of the dirt-bearing stratum. Again, 
the variable currents of the air tore the upper portion of the 
brown haze into isolated masses which passed before the sun 
like ordinary clouds. This cloud-like form of the dirt masses 
is characteristic of all these mid-winter storms when at their 
highest, and seems to indicate the violence of the air currents 
in which they are carried. To an observer it was impossible 
to escape the conviction that the dirt was confined to the stormy 
stratum of air resting on the earth and reaching to no great 
hight above it. Also that the dust was driven along by the 
violent circulation of the atmosphere and reached the earth 
