FE. Loomis — Observations of the U. S. Signal Service. 17 
winds push down with unusual force over Dakota and Minne- 
sota, because during the winter months the coldest portion of 
the American continent is near this meridian, and the contrast 
between the temperature of Minnesota and that of the Gulf of 
Mexico is greater than is found for an equal difference of lati- 
tude east of the Mississippi. 
These considerations do not explain the high barometer in 
the case of No. 9, and in similar cases which frequently occur 
in the Southern States; nor do they explain the long continu- 
sure. No. 14 presents a case in which an area of high barome- 
This conclusion is confirmed by the observations on the direc- 
tion of the upper clouds made by the observers of the United 
States Signal Service, at the dates of the low barometer recorded 
In my eighth paper. In each of these cases when there was a 
well-defined area of high pressure on the east side of the area of 
Ow pressure within the limits of the United States, I selected 
all the cases in which the direction of the upper clouds was 
recorded at stations intermediate between the centers of | 
and high pressure. The results are given in the following 
table in which column first shows the date of the observation; 
column second shows the station; column third shows the 
direction of the surface wind, and column fourth shows the 
direction of the upper clouds at the given date and station. _ 
_ It will be seen that the surface winds were in all cases blow- 
‘Ing inward towards the low center, but inclined to the right; — 
that is, they circulated around the low center, and at the same 
time moved spirally inward. The upper clouds were in all 
cases moving away from the low center and towards an area of — 
h pressure on the east or southeast side. The movement of 
the upper clouds was sometimes directed almost exactly towards 
Am. Jour. weet: * Serres, Vou. XVI, No. 91.—Juxy, 1878. 
