Spraying to Prevent Frost. 109 



" If the hoed crops of the farm are cultivated 

 with reference to securing a constant supply of 

 moisture in the upper soil to draw by capillary 

 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 - stalky 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 

 stayed 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 



