ORCHARD HEATING 29 



The oil to use. At present the smudge oil put out by the vari- 

 ous oil companies seems to be the cheapest. 



Oil can be purchased in tank-car lots from i|- cents to 3 cents 

 per gallon. In barrels it will cost 4 J, cents to 6 cents per gallon. 

 The amount of oil necessary will depend upon the number of 

 frosty nights and the length of time that heating will be necessary. 

 This will be hard to forecast, and sufficient oil should be provided 

 to last through more than the ordinary number of frosty nights. 

 In most seasons from one to three frosty nights are encountered. 

 The frosty period usually occurs late in the night, after midnight, 

 and lasts until sunrise. From three to five hours will usually cover 



Fig. 7. Filling orchard heaters. (Oregon Agricultural Experiment Station) 



this period. However, certain nights may occur when it will be 

 necessary to keep the fires going from eight to ten hours, and 

 others when perhaps only an hour's heating will be necessary. 

 From three to six gallons of oil per heater should be provided. 

 If there is good storage, this oil will keep from year to year, so 

 that what is not used may be kept over for the next season. The 

 grower is much better prepared for emergency if the larger amount 

 of oil is on hand. Oil is too cheap to allow shortage of supply 

 to occur. 



How to store the oil. For storing oil a cement cistern lined 

 with asphalt gives the best results. This is especially true if the 

 cistern is located on a slope so that the oil may be handled by 

 gravity from the tank wagon to the cistern and from the cistern 

 into the distributing wagon. These oils are very difficult to handle 



