14. & Loomis—Observations of the U. S. Signal Service. 
5th shows the barometer at station 4 (2,898 feet above the sea}. 
Columns 6th and 7th show the mean height of the barometer 
at stations 1 and 4 for the month of May: columns 8th and 9th 
show the mean height of the barometer at stations 1 and 4 for 
the months of May and June combined. Column 10th shows 
the mean height of the barometer at each hour of the day for 
the month of August, on the summit of Mt. Mitchell, N. GC 
(elevation 6,691 feet), and column ilth shows the barometer at 
the base of the mountain (elevation 2,560 feet). 
t the base of Mt. Washington the principal maximum — 
occurs at 85 A. M., but on the summit it does not occur until 
noon, being a retardation of 34 hours, which is almost identi 
cally the same as we have found on page 7 by a comparison of 
High Winds on Mount Washington. 
Tn order to stady the laws of the winds on Mount Washing: 
ton, I selected from the published volumes of the Signal Ser | 
vice observations (Sept., 1872 to Jan., 1875) all those cases im 
which the velocity of the wind was at least sixty miles per hout. 
The number of these cases was 484, of which 117 occurred at 
35 
7.85 A. M., 187 at 4.85 Pp. M. and 180 at ll p.m. Thus we see 
that at 11 P.M. the frequency of high winds is 42 per cent 
greater than at the other hours of observation. But near the 
level of the sea the force of the wind at 11 P. M. is ape 
bear its minimum, so that we conclude that the causes which | 
produce high winds on Mount Washington are mainly inde- 
pendent of the causes which determine the ordinary diurnal 
chanze in the force of the wind near the level of the sea. 
e following table shows the average number of cases of 
violent winds for each month of the year. 
. 
Winter. 
Dee. 22.7 
Jan. 21.3 + 21.2 
Feb. 19.5 
Autumn. 
Sept.11.7 
Oct. 9.7} 13.8 
Nov. 2 
Sp: 
Mar. 17.5 
Apr. 15.5 } 14.0 
May 9.0 0.0 
Thus we see that during the winter months, high winds are 
twice as frequent as during the summer months, while near the 
level of the sea high winds are seven times as frequent during” 
the former period as during the latter period. 
‘The following table shows the number of cases in which the 
wind blew from the different directions at the time of these 
high velocities. 
