Frost and the Prevention of Damage by It. 



29 



distillate or gasoline and fuel oil. (See fig. 7.) These torches drop 

 the burning liquid into the heaters, starting combustion immedi- 

 ately. Lard-pail heaters when new are sometimes difficult to light. 

 If the burning liquid from the torch is poured in a ring on the edge 

 of the heater, no difficulty will be experienced. After three or four 

 firings the carbon deposited on the rim of the heater acts as a wick 

 and a little burning liquid dropped anywhere in the oil will ignite 

 it readily. 



Many fruit-growers hire school boys to light the heaters and have 

 been able to place great dependence on them. 



Coal fires should be carefully built up with oil-soaked waste or 

 paper and a small amount of kindling. If a portion of the fires fail 

 to burn a great deal of valuable time is lost in going back over the 

 same territory again. 



9PM. 



34.M. ___ 4'A.M __ SAM. 6A.H. 



J L 



J L 



Temperature of sfaf/on fi >efare firing 



Tefnpcrafire a/ yror/orf C otrrstd* /reared orchard. 



Terrtperafure 'of sfarfsart fi *r/rr> heaters tvrniry. 



FIG. 14. Continuous records of the temperature at stations shown in figure 13, showing 

 the effect of firing on the temperature. Low-stack oil heaters of the type shown in 

 figure 6 were used. 



Storage of Fuel. In order to carry on orchard heating success- 

 fully it is necessary to have enough fuel within reach to last through 

 the longest cold spell likely to be experienced. Too many instances 

 have been noted where the crop has been protected successfully 

 through several cold nights at considerable expense, only to be lost 

 on one cold night on account of lack of fuel. Where orchard heat- 

 ing is practiced by many growers in a community it is a good plan 

 to buy and store large quantities of fuel oil on a cooperative basis, 

 as is done in southern California. Orchards located near the storage 

 tanks can haul directly from them, but in the case of those located 

 a mile or more distant, storage tanks should be provided in the 

 orchard. 



The necessity of pumping oil from storage tanks should be avoided 

 by raising the tanks high enough above the ground so that the oil 



