270 The Principles of Fruit-growing 



not move more than 1 or 2 miles an hour. In young 

 orchards, with the fruiting area low, practically double 

 the quantity of fuel-oil as given will be necessary. The 

 simple lard-pail type of heater, or, for that matter, any 



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FIG. 96. The using of wood for heating an orchard, fifty fires to the acre. 



type of orchard-heater providing a burning area of about 

 44 square inches, will burn about one quart of fuel-oil an 

 hour. Fifty-one gallon heaters will burn approximately 

 twelve and one-half gallons of fuel-oil an hour and if this 

 oil costs 4 cents a gallon, the cost an acre-hour will be 

 about 50 cents when all the pots are burning. In other 

 words, under the above conditions, it will cost approxi- 

 mately 1 cent an hour for each heater used, providing this 

 heater does not have a burning surface greater than 44 

 square inches. It will require less fuel to heat an orchard 

 in the square form than one of any other shape. The 



