Development of Modern Frost Fighting 55 



Oil and Coal for Fuel 



From the experiments that have been carried on there 

 r.nd elsewhere it seems apparent that the source of heat 

 must come from any one of three available sources viz., 

 wood, oil and coal. Which of these to use will depend 

 on the cost of the fuel laid down In the orchard.' In sec- 



Filling "Ideal" Coal Burning Orchard Heaters. 



tions where wood is still the most abundant and cheapest 

 fuel, it will be the best to use. In sections where oil can 

 be had cheaper than coal or wood, it will serve; and in 

 other sections coal will be the cheapest fuel. 



Doubtless at the present time more persons are using 

 coal for fuel in some way than any other material, and 



