United States Weather Maps for 1872-1874. 9 
belongs to that side of the storm should extend to a greater 
distance, and probably blow with increased force, which would 
cause increased rainfall upon that side, and the storm’s pe 
would incline in that direction. In like manner, if the hi 
1 s center, the 
increased precipitation on that side should cause the storm’s 
path to incline more to the northward. 
t might be supposed that the same course of reasoning 
would lead us to conclude that a storm’s progress should be 
most rapid when there is an area of high barometer on its 
eastern side. To this it may be answered, that although the 
fall of the barometer in such a case should be more rapid than 
usual, still, as the barometer starts from a point unusually 
high, the fall must continue for a proportionally longer time 
before the minimum is reached. The same consideration may 
in part explain why the progress of a storm is not as much 
accelerated by a high barometer on the northeast side as it is 
y a high barometer on the southeast side. In the former case, 
the high barometer is nearer to the track which the storm is to 
pursue, and there must be a greater fall of the barometer before 
the minimum is attained. 
Form of the isobaric curves. 
ne average form of the isobars about a storm center may be 
said to be an irregular oval, whose length is nearly double its 
breadth. In order to give a more distinct idea of the form of 
length of the arrows: a length of 0-4 inch indicatin locit 
: g a velocity 
Md at least 20/niles per was a length of 0°3 inch a velocity of 
rom 10 to 20 miles; and a length of 0-2 inch a velocity less 
than 10 miles per hour. : 
