330 Peach-Growing 



"The object sought in all methods of frost protection is to 

 hold the temperature of the air in contact with the plant 

 above the point of danger. In the attempt to accomplish 

 this certain principles are involved : 



"1. Prevention or retardation of the escape of heat from 

 the earth by the use of an artificial covering. The use of 

 smudges as a means of protection against frost is based on 

 this principle. 



"2. Addition to the air of moisture in the form of vapor, 

 with the view of obtaining the effect of liberation of latent 

 heat as the moisture condenses. The use of damp fuel for 

 smudges and the spraying of fires with water have this 

 purpose in view. 



"3. Heating the air by numerous small fires." 



Artificial covering. 



"It is a very old practice to protect plants from frost by 

 covering them with newspapers, carpets, straw, and the like. 

 This is a most cleanly and efficient method, but unfortu- 

 nately, because of the labor and expense involved, it is ap- 

 plicable in practice only in small areas, such as flower beds 

 and gardens. . . ." 



Smudging. 



"Smudging, particularly when damp fuel is used, com- 

 bines the first and second principles mentioned above — 

 the prevention of the escape of heat from the ground and 

 the addition of moisture to the air. In practice smudging 

 has not proved a very efficient method of protection. It 

 is used chiefly at present to shield the blossoms from the 

 sun during the morning hours following a frost, thus pre- 

 venting too rapid thawing. Spraying the frozen fruit or 



