United States Weather Maps. 5 
same is true upon whichever side of the low barometer the high 
barometer is situated. It seems natural to conclude that the 
result must be an increased steadiness and force of the winds 
in question. How far this conclusion is confirmed by the ob- 
servations, and what may be its effect upon the direction and 
velocity of a storm’s progress, I propose to consider hereafter. 
Consequences of the outward flow of air from an area of high 
arome 
We have found that from an area of high barometer there is 
an outward movement of the air having an average inclination 
of 42°18’ to a line drawn from the point of greatest pressure. 
Near the surface of the earth, the average velocity of this move- 
ment is 5-96 miles per hour, but as we ascend above the surface, 
this velocity is very much increased. Suppose now that the 
area of high barometer is a circle 1,500 miles in diameter; that 
the barometer at the center of this area stands at 30°50 inches, 
and that the average velocity of the entire column of air is 18 
miles an hour, which is the mean between the velocities ob- 
served near the level of the sea and on the top of Mt. Washing- 
on. Assuming that the average inclination to the radius is 
42° 18’, we find the resolved portion of the wind’s motion in 
the direction of radius is 18-3 miles per hour. What must be the 
and even longer. Thus from Dec. 29, 1872, to Jan. 2, 
the barometer at New Haven was never below 30°30; from 
Ov. 29 to Dec. 8, 1873, the barometer was never below 30°35 ; 
te ee Dee. 31, 1878, to Jan. 6, 1874, it was never below 
These facts appear to me to prove that areas of high barome- 
ter are maintained by a continued accession of air in the upper 
regions of the atmosphere, and this accession is probably de- 
rived from the air which ascends near the center of an area of 
low barometer, In my former article, page 10, I have shown 
that near the center of an area of low barometer there is a 
