528 



Bulletin 316 



Fig. 146. — Rayo orchard heater 



generally has been discarded, because the baskets will not retain their 

 shape when heated. The most satisfactory coal burner is an inverted 



cone made of sheet iron perforated at 

 the bottom for draft and holding per- 

 haps half a bushel of coal. It is placed 

 a few inches above the ground and sup- 

 ported on iron legs. The coal burners 

 should be prepared in advance, so as to 

 be lighted quickly when the temperature 

 approaches the danger point. From 

 twenty-five to fifty heaters per acre 

 usually are considered sufficient for the 

 ordinary orchard of medium age, but for 

 young orchards the number should be 

 increased. A medium grade of soft coal 

 makes a satisfactory fuel, and twenty-five to thirty pounds per heater is 

 sufficient for four hours burning. For the greater part of New York 

 about $2 per night per acre, exclusive of labor in handling, probably 

 would be the maximum cost of heating with coal. 



Oil. — For the commercial orchardist, oil is probably the most economical 

 fuel, not because it is more efficient than wood or coal, but because it is 

 more easily handled. Crude oil and distillate are used chiefly for this 

 purpose. Crude oil is the cheaper, but is less satisfactory because it 

 contains a certain percentage of water, which tends to extinguish the flame 

 and causes the pots to boil over. Also, it is difficult to handle in cold 

 weather and in 

 burning it gives off 

 large quantities of 

 soot. Distillate 

 is a by-product of 

 crude oil remain- 

 ing after the kero- 

 sene and gasoline 

 have been extract- 

 ed. It is free from 

 water, ignites 

 readily, burns 

 freely, and leaves 

 little residue. The 

 question of an oil 



fuel that is satisfactory both in price and in efficiency is not yet 

 settled. 



Fig. 147. — Hamilton orchard heater. When in use the cover is 



partly withdrawn 



