Observations of the United States Signal Service. 13 
the Atlantic coast; that is, the center of great rain-areas is 
found near the Atlantic coast four times as frequently as it is 
in the other portions of the United States. The center of great 
rain-areas is not found in the neighborhood of the great Lakes 
more frequently than it is at inland stations quite distant from 
the Lakes. 
The distribution ofthese fifty-five cases by seasons was as 
follows : > : 
Spring 8; Summer 9; Autumn i0 and 16; Winter 12; 
showing a slight predominance of great rain-areas in autumn 
and winter. In my last paper it was shown that excessive 
rains at single stations were most common during the warmest 
months ; but it appears that very extensive rain-fails are most 
common during the cooler months. 
The distribution of these cases according to the hour of the 
day was as follows: 
7.35 A.M. 25 cases; 4.85 P. M. 22 cases; 11 P.M. 8 cases. 
98.980 with regard to great rain-falls at single stations south of 
atitude 36°. It is essential to the accuracy of this conclusion 
rain-column makes no mention of rain. It is presumed that 
generally in these cases the rain had but recently commenced, 
and the observer thought it would be equally satisfactory to 
report the entire rain-fall at the time of the next observation. 
There seems no reason to question the conclusion which these 
numbers indicate, viz: that the causes which produce exces- 
Sive rain-falls in the United States, act with less intensity in 
the evening than during the remainder of the day. 
Areas of low pressure without rain. 
order to compare the influence of a very small rain-fall 
n 
bre exhibits these cases. Column 1st contains the number 
of reference; column 2nd shows the day and hour of observa- 
