18 E. Loomis—Results derived from an examination of the 
No clouds. Partly cloudy. b wcarithe Z 
Oct. 19.2 5 stations. 2 stations. 2 stations. 
m3 8 < 2 ¥ none. 
20.1 9 2 5 ae E 
20.2 13 si T oe 3 stations. 
20.3 15 rr 3 ae % 
21.t 5 eg 7 ms 3 ag 
21.2 4 ft 9 5 = 
and Duluth; 21.1, St. Paul, Duluth and Escanaba; 21.2, Santa 
Fe, Duluth, La Crosse, Keokuk and Toronto. Six of these 
cases occurred in the neighborhood of the Rocky Mountains, 
so remote from the center of least pressure that if there ha 
been a rain-fall in that vicinity, it could not be supposed to be 
the cause of the barometric minimum under discussion. The 
long continuance of clouds at Duluth, and the extension of this 
cloud area on the 21st indicates an upward movement of the 
atmosphere attended with a slight precipitation of vapor, and 
there may have been rain-fall at places further north. But 
when we consider that in the Southern States a heavy rain-fall 
covering an area several hundred miles in diameter exerts 
scarcely any appreciable influence on the barometer, we cannot 
suppose that the very limited rain-fall which may possibly 
have occurred from October 19th to the 21st had any sensible 
influence in the production of the barometric minimum, or in 
causing its eastern progress, so that it seems safe to conclude 
that rain-fall is not essential to the formation of areas of low barom- 
eter, and is not the principal cause of their formation or of their 
earth’s rotation the result was a diminution of pressure over 
the region between the Rocky Mountains and Lake Superior. 
These two areas of high barometer on opposite sides of the 
low area were remarkably persistent from Detaber 19th to 21st, 
but advanced eastward at about the same rate as the barometric 
minimum. Plate IIT, shows the direction of the winds October 
20th, 4.35 p.m. They indicate a decided inward movement 
of the air and a circulation about the center of low pressure. 
At several of the stations the winds were uncommonly strong. 
The following table shows the direction and force of the wind 
where the velocity was greates 
