6o2 



Journal of Agricultu?c 



[lo Sept., 1910. 



them ; they were also used in Carthage of old, and even in Peru the natives 

 had recourse to them before the Spanish Conquest. Much valuable infor- 

 mation concerning their use will be found in the article by Mr. R. Dubois 

 <Vol. I., p. 877). _ . 



Some misconception appears to exist ni the minds of a good many 

 persons as to their mode ot action. It is often thought, for example, that 

 they merely act by protecting the frozen shoots from the first rays of the 



SMUDGE FIRES IN USE AT DOOKIE. 



sun — that they only act, in fact, by preventing a rapid thaw. No doubt 

 they exert a very considerable influence in this direction, but, provided they 

 ar^ sufficiently dense, and especially if their production is commenced early 

 enough, they also considerably retard the loss of heat by radiation and 

 keep the temperature of the lower air higher bv a few degrees than it 



I 



LESTOUt's '' FOYERS " (sMUDGES). 



would otherwise be. Frosts do not occur on cloudy nights. The effect 

 ■Of' the smoke is to protect from frost in the same way that natural clouds 

 •do. It must be remembered that a gain of only a couple of degrees may 

 mean the difference between serious damage and none at all — and such a 

 gain is quite feasible. French authorities consider that this method gives 

 good results provided the temperature does not fall lower than 5^ deg. to 

 7 deg. below freezing point (32 deg. F.). It naturally follows that best 



