United States Weather Maps for 1872-1874. 7 
Obs. of 1872 and 78, Obs. of 1874. Obs. of three years. 
Course o Axis of Course o Axis of Course of Axis of 
Storm. Rain-area. Storm, Rain-area. Storm. Rain-area. 
N. 40°H.|N. 53°H.)N. 53° HR.) N. 54°E.|N. 44°E.|N. 563° E. 
N.116 E.|N.118 E.|N. 100 E.|N. 109 E.|N. 111 E.|N.115 E. 
From the result of three years’ observations, it appears that 
when the course of a storm is most northerly, the axis of the 
rain-area is inclined to the storm’s path 9° toward the south ; 
but when the course of a storm is most southerly, the axis of 
the rain-area is inclined to the storm’s path only 4°. If, then, 
in any case we can learn the precise limits of the rain-area 
about a storm-center, we ought to be able to predict with con- 
siderable confidence the direction and velocity of the storm’s 
progress. 
Influence of a neighboring area of high barometer upon the pro- 
gress 0 orm. 
into eight classes, according to the direction of the center of 
high barometer from the center of low barometer. From the 
center of low barometer I drew eight radii, making with each 
other angles of 45°, and so situated that two of the octants 
should be bisected by a meridian line. These octants are desig- 
nated by the terms, north, northeast, east, ete. A large sheet 
of paper was then ruled with appropriate divisions for each of 
the octants, and when the area of high barometer was on the 
north side of the storm center, the velocity and direction of the 
storm’s path were entered in the column headed north. I pro- 
ceeded in like manner with each of the cases in succession. 
An average was then taken of the directions and velocities in 
the several columns. 
The following table shows the result of this comparison for 
1872, ’73 and 74. Column Ist shows the direction of the area 
of high barometer from the storm center; column 2d shows 
the number of cases employed; column 3d shows the average 
velocity of the storm’s progress; and column 4th shows the 
direction in which thé storm advanced. — 
