ORCHARD HEATING 31 



at best, and unless all leakages are prevented, it becomes doubly 

 disagreeable. One should dress for dirty, oily work. 



How to light the pots. The pots are lighted by the use of a 

 gasoline can with valve fixture, which makes it possible to squirt a 

 small amount of gasoline on top of the fuel oil. A torch can be 

 made of a corncob fastened to a piece of wire and soaked in fuel oil. 



It requires about forty-five minutes for three men to light 600 

 pots, but one man could easily light 300 pots per hour, providing 

 his torches and gasoline can worked well. 



When to light heaters. The temperature at which the fires 

 shall be lighted will depend upon the predicted temperature for 



Fig. 9. Heating a small home orchard with fire pots in full blaze. (After Iowa 

 State College) 



the night and the rapidity with which the temperature falls. If a 

 very cold period is expected or if the temperature is falling rapidly, 

 the fires should be lighted when the temperature is several degrees 

 above the danger point, probably 33 degrees. If but little frost is 

 expected or if the temperatures are falling slowly, the heaters need 

 not be lighted until the temperature very nearly reaches the danger 

 point, 29 or 30 degrees. 



Predicting the temperature. The orchardist should provide 

 himself with such information and equipment as will enable him 

 to know when to expect frost and freezing temperatures. The 

 United States Weather Bureau sends out daily forecasts for the 

 succeeding twenty-four hours. The orchardist should supplement 

 the forecasts sent out by the Weather Bureau by his own obser- 

 vations. Local conditions influence the temperature and humidity 



