250 TRAVELS THROUGH NORTH AMERICA : 
the eastward of the Blue Ridge, where it very 
rarely happens that the thermometer is as low 
as 0° above cipher. 
In Pennsylvania, the range of the mercury in 
Fahrenheit’s thermometer has been observed 
to be from 24° below cipher to 105° above it; 
but it is an unusual occurrence for the mercury 
to stand at either of these extreme points; in 
its approach towards them it commonly draws 
much nearer to the extreme of heat than to 
that of cold. During the winter of 1795, and 
the three preceding years, it did not sink lower 
than 10 above cipher; a summer however 
seldom passes over that it does not rise to 96°. 
It was mentioned as a singular circumstance, 
that in 1789 the thermometer never rose 
higher than 90°. 
Of the oppression that is felt from the sum¬ 
mer heats in America, no accurate idea can be 
formed without knowing the exact state of 
the hygrometer as well as the height of the 
thermometer. The moisture of the air varies 
very much in different parts of the country; 
it also varies in all parts with the winds ; and 
it is surprising to find what a much greater 
degree of heat can be borne without incon¬ 
venience when the air is dry 'than when it is 
moist. In Mew England, in a remarkable dry 
air, the heat is not found more insupportable 
when the thermometer stands at 100°, than it 
f 
