168 



THE IRRIGATION AGE. 



or dew this great amount of latent beat is 

 given off into the atmosphere, and tends 

 to keep it at an even temperature. You 

 have two forces at work. Firstly, the 

 radiation or loss of heat is reducing the 

 temperature to the dew-point, while the 

 heat given off by the condensation of the 

 vapor is keeping up the temperature just as 

 fast as it falls to the dew- point. The re- 

 sult is that unless the radiation is very 

 great the temperature does not fall. Of 

 course this theory does not work except in 

 cases where slight frosts would otherwise 

 occur. For instance, where in a dry at- 

 mosphere the dew point would not be 



amount of heat that was expended in 

 forming the vapor, and how enormous thi& 

 is may be judged by the fact that the con- 

 densation of a pint of water from its 

 vapor state will result in enough heat 

 being given off to raise more than five 

 pints of water from the freezing to the 

 boiling point. We thus arrive at the 

 seeming paradox that the formation of 

 frost from vapor produces heat in the at- 

 mosphere. 



In using smudge fires it should be un- 

 derstood that the heat of the tire has but 

 little effect in diminishing the intensity of 

 the frost, almost the entire protection 



WIND MILLS AND KESERVOIR OF E. E. FRIZELL, NEAR LARNED. KANSAS. 

 30 acres in alfalfa, 25 acres orchard, 10 acres Irish potatoes, 5 acres sweet potatoes, r. acres onions, 5 acres 



cabbages; total, 80 acres. 



reached before the temperature had fallen 

 to 29, the dew-point may be reached at 

 31 in a moist atmosphere. In the 

 former case the peach buds would be 

 destroyed, while in the latter case they 

 would escape injury. Hence the object of 

 keeping the surrounding atmosphere moist, 

 and this can be attained by frequent irri- 

 gations or even spraying of the orchards 

 at the critical period of blossoming. That 

 this is not a fallacious theory has been 

 proved over and over again by orchardists 

 who have kept their land well saturated 

 with water during the blossoming season, 

 and who have escaped injury from frost 

 while their neighbors who have failed to 

 follow this practice have suffered. The 

 heat given off by the condensation of vapor 

 into dew or frost is exactly equal to the 



being gained by the screen of smoke pro- 

 duced. The efficiency of smudge tires 

 may be greatly increased by spraying 

 them with water, thus adding vapor to the 

 atmosphere and raising the dew-point, 

 for as has already been explained the 

 dew-point is reached at a higher tem- 

 perature when the vapor in the air is in- 

 creased. Moreover, by spraying the fires, 

 the heat, which would otherwise establish 

 an upward current of warm air that con- 

 ducts the heat upward and beyond the 

 space needing protection, is utilized in 

 forming vapor and distributed through 

 the lower stratum of air where it is most 

 needed. As soon as this vapor is con- 

 densed at the dew-point, this latent heat 

 is set free and tends to raise the tempera- 

 ture. Every quart of water thus evapo- 



