60 The Fruit-Growers Guide-Book 



one to get an approximate idea of the first cost of equip- 

 ping an orchard for heating. The additional expenses of 

 the operation will depend on the number of nights the 

 heaters will be used, and the cost of the labor. As a rule 

 the heaters are needed for four or five nights in the spring 

 and with oil heaters it is the general experience that one 

 man can take care of five acres while it will take possibly 

 two men to handle that many acres where coal burners are 

 used. 



During the next ten years there will no doubt be as 

 great a development in the styles of orchard heaters in 

 use by the commercial orchardists as there are in the 

 styles of spraying machines that are in use today, and 

 which were in use ten years ago. This is to be easily sur- 

 mised as the heaters, both coal and oil, which are now in 

 use are not altogether satisfactory in many respects. One 

 of the principal troubles with the oil burning pots is that 

 when the oil has burned down half way or more in the pot 

 the fires are not as hot as when the oil is at or near the 

 top of the pot This is because the upward currents of 

 heated air prevent the oxygen getting down to the surface 

 of the oil to make the flame. This slow combustion of the 

 oil causes it to deposit larger amounts of soot around the 

 top of the pot and throwing more of it off into the air. 

 Several attempts have been made to perfect a heater that 

 had a reservoir holding several gallons and fed through 

 a pipe into the fire pan. But up to the present time 

 no one has succeeded in perfecting such a reservoir 

 heater which will satisfactorily burn gas or fuel oil in 

 cold weather. These oils are thick and gummy, and 

 even become almost solid in cold weather, so that 

 when the oil must flow through a pipe, as is the case with 

 all of the heaters of this class at the present time, the oil 

 thickens so that it will not flow. 



Aside from this trouble, the heavy oils which are used 

 leave a thick deposit of residue or asphalt in the bottoms 

 of the heaters, so that after burning for three or four 

 nights this sediment must be scraped out. To do this it 



