- 
JANUARY 18, 1884.] 
SCIENCE. 
Average rainfall within 
isobar 29.80”. 
0.078” 
0.149 
0.159 
Change of central depression in 
twenty-four hours. 
+ 0.10” (i.e., storm decreasing). 
— 0.05 
— 0.128 (i.e., storm increasing). 
Rain, therefore, is shown to aid in determining 
the velocity, direction, and development of our 
storms, as has already been inferred. 
Thus far in regard to the motion of the storm 
65 
tions here shown has already been discussed. 
It should be added, that the unexpected ap- 
proach to equality in the wind’s strength on 
the right and left (south and north) sides of the 
storm is probably in large part due to the wind 
on the north coming but little retarded from 
the sea, while that on the south has lost much of 
its proper velocity by blowing long over land; 
so that, while the winds should theoretically 
show a less velocity on the left than on the right 
side of the track when the storm moves over a 
uniform surface, this inequality might be largely 
i oO 70 CO oO G0 O. 
= z - Ae LO IDO 9 80 70 60 50 40 50:20 10 0 4020 60 £0 SO7 GO 
Ae 
s ¥] B N 
of 
> 
= z a7 
ek Grn s 
= 
30 and more == About 3s storms in the year. 
25 30 4 5 12-15 (6k ‘6 
SSO E 9-12 «6 Gc. ee TT 
‘ 6-9 6¢ 6 ee 6é 
y = = 3-6 66 66 66 66 
ae 
SS 5-10 
SS Under 5 
oO GO. 50 HO “OO 
AVERAGE TRACKS OF STORMS FROM THE ROCKY MOUNTAINS TO THE URAL. 
as a whole. The winds of the storm blow 
faster, the more marked the central depression 
and the closer the isobars. If the space on the 
signal-service maps between adjoining isobars 
(the difference of their pressure being one-tenth 
of an inch) measure one hundred and thirty 
miles, the wind will probably blow five miles 
an hour ; if eighty miles, thirty miles an hour ; 
if forty-five miles, fifty miles an hour. There 
is, however, much variation from this rule, 
depending on the form of the ground and the 
neighborhood of the lakes or the sea. The 
average direction, inclination, and velocity of 
our storm winds in the four quadrants is shown 
in fig. 21. The relation of the several inclina- 
counteracted by the relations of sea and land 
that obtain in the eastern part of our country. 
This is confirmed by finding the winds on the 
left side of the storms of northern Europe much 
weaker than on the right; for here the progres- 
sion of the storm, and the relation of sea and 
land, combine to produce this effect. Our space 
forbids more detailed consideration of the vari- 
ation of our storms with the seasons; and the 
reader desirous to pursue the subject farther 
should provide himself with the government 
daily weather-maps, which may be had by sub- 
scription to the chief signal-officer in Wash- 
ington, and should consult Professor Loomis’s 
essays in the American journal of science for 
