6 SANTA BARBARA SOCIETY OF NATURAL HISTORY. 



Blodgett asserts that "this mist is peculiar, and is a con- 

 densation produced by contact of the cold air alone, and not 

 by natural condensation in the volume coming from the sea; 

 that the air out at sea is usually clear, and the mist only 

 forms a narrow rolling line along the place of contact of the 

 volumes differing so widely in temperature." When this sea 

 air passes over the land on the coast from Santa Barbara to 

 San Diego, its percentage of humidity is only about 70. As 

 this wave of air passes on into the interior, its capacity for 

 moisture is rapidly increased by the elevation of the temper- 

 ature, and the percentage of humidity is reduced to 60 and 

 even to 50 by the time it has reached the Colorado Desert. 

 On the west coast of England, Ireland and Scotland, where 

 there is no intervening cold current of water to deprive the air 

 of its excessive humidity, the percentage averages from 83 to 

 85. Buchan, in his Handbook of Meteorology, states that 

 "the air to an inhabitant of Great Britain would feel very dry 

 when the percentage was as low as 73, which is the lowest 

 mean humidity that occurs in Scotland during May, the driest 

 month." In the Atlantic and Gulf States of the Union the 

 humidity ranges from 75 to 83. 



'What percentage of humidity in the atmosphere is most 

 conducive to health? At the present time this question cannot 

 be definitely answered, for the reason that so few observations 

 have been made of the comparative dryness and humidity of 

 different countries. From the imperfect data given, it is esti- 

 mated that the larger portion of mankind have their homes 

 in an atmosphere averaging 80 per cent, or more of humidity. 

 There are four regions of extreme aridity — one extending 

 across northern Africa and reaching beyond the Red Sea into 

 central Asia; another is that of western Australia; a third 

 that of Peru and Chili; and the fourth that of the larger por- 

 tion of the Territory of the United States lying west of the 

 Rocky Mountains and south of latitude 48, except the coast 

 region. There is also a small district on the west coast of 

 Africa, north of the Cape of Good Hope. The percentage of 

 humidity in these arid regions averages only from 35 to 60. 



