8 E. Loomis—Results derived from an examination of the 
extent on the northeast side, one about Baltimore and the 
other about Montreal. 
From the preceding statement we perceive that in the United 
States, south of latitude 36°, great rain-falls are accompanied 
by a cyclonic movement of the air which sometimes appears to 
be the result of a neighboring area of iow pressure, and some- 
times of an area of high pressure, and the latter case is about 
as frequent as the former. North of latitude 36° rain-areas are 
most frequently associated with areas of low barometer and 
generally they are found on the east side of the center of low 
pressure; but occasionally they are found on the west side of 
the center of low pressure, and this case occurs most frequently 
in the neighborhood of the Ohio valley. Extensive rain-areas 
sometimes occur in the Northern States at a great distance from 
a low center, where they appear to be as much under the 
a local cyclonic movement of the atmosphere. 
Of the fifty-five cases enumerated in the table on page 2, 
in thirty-eight cases the wind blew from some quarter between 
northeast and southeast, either at the date given in the table or 
at the time of the preceding observation. Of the seventeen 
remaining cases, in five of them the air was reported as calm ; 
in three of them the wind was from the south, and two of the 
cases occurred on the summit of Mt. Washington. In one of 
the remaining cases the velocity of the wind was only two 
miles per hour; in another case the velocity was three miles 
r hour; in a third case it was seven miles per hour, and in a 
ourth case it was nine miles per hour. There remain only 
three cases in which at both the observations the wind was 
west or northwest. It seems probable that this northwest 
current crowded under the southeast current lifting it up from 
the earth’s surface and thus condensing its vapor, and that the 
south wind at Philadelphia was the result of the meeting of the 
southeast wind from the ocean with the northwest wind of the 
interior. 
In No. 47, as has been already mentioned on page 4, the 
center of the rain-area was on the northwest side of the center 
of low pressure. It seems probable that in this case the violent 
southeast wind from the ocean extended further west than 
Buffalo, and that its vapor was condensed by its being elevated 
from the earth’s surface by the crowding of the northwest wind 
