88 
GEOLOGY OF NOKTH CAROLINA. 
Atmospheric Pressure. — Barometric observations are in hand for only 
three stations, the two last named and Asheville; but there is not a 
complete series through an entire year for any of these points, and they 
have not been reduced or prepared for publication or discussion ; so that 
this department of the climatology is reserved for a later volume and a 
larger accumulation of data. 
Clouds , o be. — Neither a copious annual precipitation, nor abundant 
humidity necessarily implies a prevalence of clouds and fogs. These 
elements of climate require to be ascertained independently. Excessive 
cloudiness, not less than excessive moisture, is unfavorable to many of 
the highest and most profitable forms of agriculture, to viticulture, for 
example, and to the ripening of fruits, and it also affects very directly 
the prevalence of certain forms of disease ; and it is a subject worthy of 
much fuller treatment in a general discussion of the climatolog} 1 of the 
State, than can now be attempted, and indeed than the present data would 
justify. The table of relative cloudiness which follows, although not as 
full as is desirable, will serve to convey a reasonably just impression of 
the general character of this feature of the climate of the State, and of 
its particular sections. The term fair describes the days for which the 
average of the three observations of the clouds, morning, noon and night, 
is less than one-third • cloudy , those for which this average is above two- 
thirds ; and rainy , the days on which rain fell, no matter how little or 
for how short time. So that it very often happens that the rainy days 
belong to the class of fair days. It will be observed that more than 
one-third, (about three-eighths) of the year is set down as fair ; about 
one-third, as cloudy; leaving nearly a third, (from 100 to 112 days) un- 
classed ; being those which are partly cloudy, and partly fair, the cloudi- 
ness lying between one-third and two-thirds. 
The greatest number of fair days is found in the eastern division, and 
the smallest number of cloudy and rainy ; and the middle region is cred- 
ited with the largest amount of cloudiness. 
Of the stations, Beaufort records the greatest number of fair days, and 
Oxford and Charlotte (along the mean isothermal), the greatest number 
of cloudy, and Charlotte and Newborn (and Wilmington) the most frequent 
rains, the number for these points being very much above the average for 
the State. 
It is worthy of note that the number of rainy days, contrary to the 
common notion, is less in the western section than in the State at large, 
and less than in the other divisions except the eastern, with which it 
agrees in this particular ; aud further, that there is greater cloudiness and 
