10 =. Loomis— Observations of the U. S. Signal Service. 
Nos. 8, 24, and 45, in which there were not at least two distinct 
rain-centers. In No. 45 there was apparently a subordinate 
rain-center, near Charleston, and in No. 8 there was a fall of 
of precipitation, and this fact suggests the idea that those con- 
ditions which are favorable to rain-fall at one locality, are 
generally favorable to rain-fall over a much larger district, and 
this often results in a A onaateolae precipitation at several 
points remote from each ot 
Plate IT exhibits the aoa areas for July 27th, 1873, at 4.35 
P.M. Here we find four rain-areas showing a rain-fall of at 
least one inch, and an equal number of areas showing a smaller 
rain-fall. The dolewte, table shows the greatest amount of 
rain observed at any station within each of these areas: 
Rainfall July 27, 1873, 4.35 Pp. M. 
Washington _... 2°12 inches. Shreveport ----- 0°84 inch. 
New York ._... 1°54 Breckenridge _.. “45 “ 
Nashville _..... Loo Wilmington _... ‘18 “ 
Eastport --__... EOGs = Denver. csi be 
It is possible that the Washington rain area was not entirely 
distinct from the New York area, but the observations clearly 
indicate two centers of greatest rain-fall During the time o 
this rain-fall, the barometer was a little above 30 inches at all of 
the stations here mentioned, except Breckenridge. The arrows 
show the prea: of the wind at 435 Pp. M. There ae 
e 
miles per hour, no perceptible effect was produced upon the 
barometer. 
A considerable number of the cases mentioned in the table 
on page 2, exhibit a variety of rain-areas nearly as remarkable 
as that shown in Plate I. Among these may be mentioned 
Nos. 1, 2, 8, 12, 14, 38, "36, and 41. 
In order to determine the duration of great rain-falls, I 
selected all those cases in which any of the rain-falls mentioned 
in the table on page 2, were followed by at least four inches 
of rain (total amount at the eighty stations) during a succeed- 
ing period of eight igs The following table shows the 
result of this compariso 
