FROST 



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temperature is taken at different places and in- 

 < teresting illustrations can be seen of its activity and 

 temperature. Who has not noticed that along the 

 slopes of foot-hills there is an interval of ground 

 immune from spring frosts which create havoc on 

 higher altitudes, as well as in the valleys ; and in 

 riding over country we invariably notice chilly air 

 in the depressions. 



If a fig farm slopes naturally to lower ground a 

 prevention of atmospheric drainage would be in- 

 jurious unless placed upon the highest boundary 

 ridge to deflect colder air from the outside; even 

 then it would probably encourage frosts instead of 

 mitigating them. If an orchard is in a depression 

 from all sides the more it is protected the better, 

 for, in such cases, cold air accumulates around the 

 trees during every still night. Such causes frost- 

 ing of tender limbs whenever the atmosphere falls 

 within two degrees of freezing, for evaporation 

 goes on so rapidly from the surface of new leaves 

 that its process reduces temperature at least two de- 

 grees lower than the surrounding air, this being a 

 potent reason why new growths are most susceptible 

 of injury. 



