Spraying to Prevent Frost. 109 
“Tf the hoed crops of the farm are cultivated 
with reference to securing a constant supply of 
moisture in the upper soil—to draw by eapillary 
action of the soil upon the reservoir of water in 
the subsoil, and at the same time keep the surface 
soil in such condition as to prevent the too rapid 
dissipation of soil moisture—the fields may be 
saved from frost by a covering as impalpable as 
air but as effectual as eider-down. Here is a con- 
servatism of highest importance for both farmer 
and fruit-grower. 
“On the night of Sept. 16, 1868, the Indian corn 
in Michigan was almost entirely killed by frost, 
only a few fields along the banks of rivers or the 
borders of lakes being spared. In these fields the 
corn-stalks the next morning were dripping with 
dew. The evaporation from river or lake during 
this dry time (only one-eighth inch of rain in two 
weeks) had moistened the air in their vicinity and 
stared off the frost. Away from bodies of water 
the air was very dry and the dew-point low. At 
the Agricultural College the temperature in the 
open air at 2 P. M. Sept. 16, was 54° F., the wet 
bulb marked 44°, and the temperature of dew-point 
was 31° F. During the night the temperature 
sank to 24° F. and a ‘black frost’ was the result. 
If the air over the whole state had been as moist 
as it was along those rivers and lakes, a heavy 
dew would have fallen everywhere, and the corn 
crop spared. 
“This immunity from frost afforded by a moist 
