ORCHARD HEATING 



Figure 1. One type of orchard heater. 



hence if the smudge were to keep the heat in the air just above 

 the ground the first night there will be little radiated to the air 

 about the trees the second or third night, because the ground 

 would be but very slightly if any warmer than the air. 



COLORLESS OR SMOKING FIRES 



In the early days of heating, the question arose as to whether 

 a plentiful supply of air should be supplied and a colorless heat 

 produced, or should only a limited amount be supplied and have 

 the burning associated with smoke. In the first case more heat 

 would be produced from the same amount of fuel, but in the last 

 case smoke is produced. The unburned material, in the case of 

 coal, would be small particles of carbon, and, in the case of oil, 

 gaseous hydrocarbons and carbon both of which are very good 

 absorbers of heat, but it should be remembered that in the com- 

 plete combustion of either of these fuels, carbon dioxide and 

 water vapor are developed, which substances though colorless 

 are also very good heat absorbers, (g) 



(g). Where whole communities have done considerable heating, 

 damage by the smoke to the house furnishings has been complained of 



