116 PROCEEDINGS OF TWENTY-SIXTH FRUIT-GROWETJS^^ CONVEfflON. 



times of frost, and that the best method is that which produces heat by 

 ^the simplest and least expensive process. Water, owir?g- to its high 

 specific heat, forms an excellent agency for the temporary storage of 

 heat energy. We have seen that in the wet smudge an attempt is 

 made to utilize the latent heat of vaporization, and theoretically this 

 has always seemed the most advantageous method. A modification of 

 the wet smudge is steam piped through an orchard. It is claimed that 

 the temperature was raised 3° whenever the steam was turned on. It 

 is also said that the coal consumed would not be more than the amount 

 used by the basket method. The estimated expense per acre would be 

 about $75. 



After frost, or rather just before a frost has ended, a spraying device 

 can be used to advantage. Its chief function is to prevent a too rapid 

 warming of the chilled fruit. It is said by horticulturists that even 

 the light coating of ice formed in this way does not seriously damage 

 the fruit. It is very likely that the latent heat of solidification set free 

 by the change from water to ice may play a helpful part; but the chief 

 effect is to prevent a too rapid thawing. In other words, both heat and 

 water should be supplied to the chilled plant slowly, and according to 

 the plant's ability to make good use of the same. At the A. J. Everest 

 ranch at Riverside, CaL, a portion of the grove is protected by sprinklers 

 at the top of fifty-foot masts. 



All screening or covering devices are in effect modified hothouses, and 

 there is no question but that a thorough protection can be accomplished. 

 The expense is the one objection. Screens are made of light materials, 

 namely, canvas, muslin, or light woodwork, and have been used with 

 considerable success. At the A. J. Everest ranch an elaborate structure 

 of lath screens is in use. There is no question as to the value of the 

 protection, but the expense is considerable, averaging perhaps $400 to 

 the acre. This lath covering may be considered as forming a well- 

 ventilated hothouse. 



Injurious Temperatures. — A list of injurious temperatures, taken 

 from Professor Hammon's pamphlet upon Frost," is also of interest, 

 and I wish the members of this Convention would test the figures given 

 in this table, so that we may determine, by actual test, their reliability. 



