HOAR FROST. 189 



not exactly either frost or thaw, or even when 

 thaw comes slowly, and the surface is covered 

 with melting snow and ice. The hard ice, and 

 unmelting snow, in the clear frosty day, affect 

 the air very little, whereas on the raw day, and 

 when it thaws partially, the air is loaded with 

 moisture, which takes the heat out of it ; and as, 

 on such days, there is seldom any direct sunshine 

 to assist in dispersing the moisture up into the 

 air, it hangs in the lower strata like a heavy fog, 

 and abstracts heat from the human body, and 

 forms hoar frost upon the hair and clothes ; and 

 whenever the temperature sinks a little, the water 

 is deposited and crystallized upon every solid sub- 

 stance, and the more so, the more slender the sub- 

 stance is, so that the grass and bushes, and the 

 twigs of the trees are frosted over with spiculse of 

 ice, which have a very pretty but very cold ap- 

 pearance. Those hoar frosts are most frequent in 

 the autumn, before the waters be so far cooled 

 down as that ice or dry frost is found. They some- 

 times occur late in the spring ; and in cold districts 

 occasionally even in the summer. 



If, in the latter part of the season those hoar 

 frosts, or white frosts " hold," by a continuance of 

 the cold atmosphere near the surface, they gene- 

 rally end in dry or black frost, and are followed 

 by cold, but healthy and hearty winter weather. 

 But if that air near the surface be warmed by any 

 cause, so that the frost " gives way," or, as it is 

 called in some parts of the country, " leaps," 

 then, if the cause of that be general, rain is the 

 immediate consequence, even though the general 

 progress of the season be such as ultimately to 

 lead to black frost, and a heavy fall of snow. 



