Adding Moisture to the Air. 107 



cable only in cranberry bogs, and in places where 

 vineyards are arranged to be flooded for the de- 

 struction of phylloxera. 



The following remarks by Haramon indicate the 

 nature of the problem : * 



"In places where irrigation can be used, it will 

 be found of great value in protecting against frost. 

 Let the water be turned on until the soil is 

 thoroughly moistened. The evaporation of the water 

 from the damp soil will tend to raise the dew- 

 point. Since evaporation takes place near the sur- 

 face this method is especially valuable in protecting 

 low plants and shrubs, but has also been found 

 very valuable in protecting citrous groves from freez- 

 ing weather. The irrigating should be done at as 

 early an hour as possible, preferably on the day 

 preceding the night when frost is anticipated, and 

 the ground kept thoroughly wet until danger from 

 frost is passed." 



"Moist soil, or localities that can be easily 

 flooded for the purpose of protection, are to be 

 preferred to dry sections of otherwise similar loca- 

 tion ; for the evaporation of the moisture from the 

 soil, on dry, cold nights, will tend to raise the 

 dew-point of the air and thus diminish the proba- 

 bility of frost. 



"The irrigation of the hillsides about a valley 

 in which protection is desired, and the growing 



*W. H. Hammon (Forecast official United States Weather Bureau), in 

 "Frost, How and When to Prevent Injury Thereby;" also pub. in Oal. Prt. Gr., 

 Feb. 8, 1896. 



