for Frosts. Ill 



efficient appliances for evaporating water could be 

 secured for about $15 an acre for the first cost. 

 "The amount of water required to raise the temper- 

 ature in the space immediately surrounding a ten- 

 acre tract would be about 500 gallons. This I have 

 demonstrated by a very complete mathematical cal- 

 culation based on experiments, but I have concluded 

 that it would require about four or five attempts 

 during a night, in order to supply the heat radiat- 

 ing into space, which would make the water re- 

 quired to be spent for a ten -acre grove, about 

 2,500 gallons. * * * * The fuel required is 

 equally certain and capable of calculation, and would 

 be about one barrel of oil, costing in Los Angeles 

 50 cents." 



TJie making of smudges. Frosts occur on clear 

 nights. This is because the earth's heat radiates 

 quickly into space. When clouds or fogs are pres- 

 ent, this radiation is checked. It is possible, in 

 many cases, to supply a blanket of smoke to check 

 radiation ; and if this cover also contains much 

 vapor of water, its efficiency will thereby be greatly 

 increased. 



The use of smoke or smudges to protect plants 

 from frost is an old practice. It is necessary, in 

 order to secure the greatest protection, that the 

 smudge be dense and uniform, and especially that 

 it be maintained until all danger of frost is past. 

 The best results are nearly always secured on level 

 lands, where the smoke will not drain away, and 

 where there are no higher lands from which the 



