108 The Principles of Fruit-growing. 



thereon of plants or trees with a large amount of 

 foliage will, by the evaporation from the soil and 

 verdure, tend to raise the dew-point of the surface 

 air as it flows downward into the valley." 



"A modified form of ' water protection which is 

 valuable in orchards is to spray the trees with 

 water. This plan is probably even more valuable 

 in protecting from freezing citrous fruits and other 

 plants which are not injured until the temperature 

 has fallen several degrees below, the freezing point ; 

 for, in these cases, the water will tend to freeze 

 before the fruit is injured, and in freezing will 

 make sensible a large amount of heat, thus pre- 

 venting further cooling of the air. For this method 

 to be successful the spraying must be continued 

 until the temperature rises." 



Kedzie writes as follows upon the subject : * 



"The vapor of water in the air (and clouds 

 also) prevents the escape of heat by radiation from 

 the soil and consequent cooling of the ground during 

 the night. But for the vopor of water in the air, 

 we should have a frost every night, in the year." 



"The old plan of a tub of water under the 

 fruit tree, and a rope reaching from the tub into 

 the branches, may serve a useful purpose. The 

 evaporation from the water in the tub and of the 

 water carried up by capillary action in the rope 

 may spread the protecting folds of the water blanket 

 over the tree. Such appliances, while of some use 

 for a small garden, would be futile for a farm. 



*R. C. Kedzie, "Forecast of Frost." Lansing, Mich., 1892. 



