FROST PROTECTION. 355 



long, hollow, brass cylinder, fitted with a piece of round 

 wick at the end. The cylinder is filled with kerosene. 



In Florida the temperature in the fired area of grove 

 has been raised as much as twelve degrees above that of 

 the surrounding area. Fig. 80 shows sweet orange trees 

 at Pierson, Fla., planted in 1888, and never touched by 

 frost. They were protected by open fires, while adjoining 

 groves not so protected were killed to the ground in 1895, 

 and again in 1899. This shows what may be done. It 

 was probably in this grove that open wood fires were first 

 used in Florida for the protection of citrus trees. 



Coal and Oil. As noted above, these two materials have 

 been used to a greater extent in California than in Florida, 

 though they have been used in the latter State as well. 



The comparative costs of the two materials given, as 

 the results of experiments in California * are as follows : 



Wire coal baskets, each 7 1-2 to 8 cents. 



Ten pounds coal (4 hours) 5 cents. 



Total cost 13 cents. 



Oil pots (3 gals.) .. ..25 to 30 cents. 



Two gallons Oil.7 T. .6 cents. 



Wicks (if used) 3 cents. 



Total cost 34 to 39 cents. 



The cost is in favor of the baskets, while the oil was 

 more readily ignited, but opinions differ as to the amount 

 of heat given off. 



The difficulty of readily igniting the coal might be 

 obviated in some such way as that adopted by Mr. James 



* California Cultivator, XIX, No. 17, 257 O. 1902. 



