FROST PROTECTION. 



353 



and west sides, but it has often been noted that 

 before the cold passes over the wind blows from every 

 point of the compass. For this reason wood should be 

 scattered, and provision made for firing all around the 

 grove. 



Throughout the grove, one large fire in every square 

 of four trees will usually be sufficient. Sufficient wood 

 must be provided to keep the fire going for seven or eight 



Fig. 79. Wood in place, ready for Hring. North Florida. The piles 



are torn down and used gradually. Note the large size of the 



wood. See also plate XVIII. 



hours at least. In less exposed regions, one small fire 

 should be provided for each tree. 



The temperature at which the fires must be started 

 depends upon the condition of the trees, and the rapidity 

 with which the temperature is falling. Ordinarily, the 

 mercury should not be allowed to drop much below 25 or 

 26 degrees F., though much will depend upon how rapidly 

 the temperature is going down. 



13 



