Inclement Weather, Diseases, Etc. 



265 



sun. These little fans, manufactured during winter, 

 cost little, and will last six years. One of Mr. George 

 Perjier's workmen can set up about eight thousand of 

 them in a day. 



For vines subjected to the method of pruning we 

 have recommended, these shelters may be placed as in 

 Figure ro2. The wooden handle is notched at A, so 

 that the wire may be let into the notch, and the fan is 

 .^stened to the top wire by means of a willow-slip. 



f^~ '-^'■^—^^y%M-i' 



[Fig. 102.J 



The shelters we have just spoken of may generally 

 suffice to protect vineyards from white frosts — that 

 is to say, from a fall of temperature not exceeding two 

 degrees below zero (centigrade — about twenty-eight de- 

 grees Fahrenheit). Unfortuately, the cold sometimes 

 exceeds this limit, reaching to three or four degrees 

 below zero (twenty-five degrees Fahrenheit). This fall 

 of temperature is no longer due to night radiations, but 

 arises from currents of air which reach us from the cold 

 regions of the north and north-east. It is not only 

 bodies near the earth that cool down, but all the mass 

 23 



