CLIMATE. 51 



per cent ; then, if the air of a certain place is only half 

 saturated it is marked as fifty per cent ; one quarter sat- 

 urated as twenty -five per cent." 



Here then is Vivenot's classification : ' ' Moderately dry, 

 56 to 70 ; moderately moist, 71 to 85 ; excessively moist, 

 86 to 100." 



We have already seen that the humidity of certain points 

 in Florida during the five coldest months is 72.7, which 

 just brings it under the heading of "moderately moist." 

 But take the whole State and the whole year, and then 

 the figures change to 69.6, and this at once places Florida's 

 climate where it belongs, under the classification of ' ' mod- 

 erately dry." 



She has reason to be thankful that it is not any drier 

 than it is, for if her atmosphere contained less moisture 

 her greatest charm would be gone. Why, do you ask? 

 Simply because a certain amount of moisture is absolutely 

 necessary to prevent great and sudden ranges of tempera- 

 ture, a thing which is quite as deleterious to health as an 

 excess of humidity. 



Who that has sat in a dentist's chair to have a tooth filled 

 does not recall with a shudder the intense aching caused by 

 the little bellows which dries the cavity to be filled? It 

 must be very dry, and it is this absence of moisture, pro- 

 ducing an intense cold by rapid evaporation, which causes 

 the excess of pain. 



We see the same principle at work in the air. For in- 

 stance, if Florida did not possess a certain amount of 

 moisture and a consequent deposit of a certain amount of 

 dew, then, instead of a night and day variation of 13° or 

 14° (often less) in temperature, there would probably be a 

 difference of 30° or 40°. 



In the desert of Sahara, where the dryness is absolute 

 and radiation at night entirely unrestrained, the tempera- 



