IN THE MONTH OF FEBRUARY, 1842. 167 
The following table, showing the difference between the dew point and the external 
temperature at Hudson, will enable us to form some estimate of the lower limit of the 
clouds. 
‘Comp.Temp. dew point. Height of Clouds. Winds, | Clouds. 
Feb. 15, 9 A. M. 4° 0! 400 Yards.|W. by S. | None. 
« « 3P,M) 17 2 1720 S.S.E. | W.S. W. 
“« 16,9A.M. 7 70 W. N. W.| N. W. 
6“ “« 3P.M. 5 4 540 N.W.byN. N. N. W. 
Be Ys Oks Le Lee 780 Ww. W.N. W. 
“ « 3P.M 12 3 1230 S.W. byS.| W. S. Ww. 
The clouds were invariably from the west, and the winds generally so, but on the 
fifteenth, when the wind was easterly, the clouds at the height of a mile were from 
west-south-west. 
Before commencing the inquiry into the causes of the phenomena of this storm, I 
propose briefly to review the phenomena of the storm of February 3. 
Storm of February 3, 1842. 
The most important features of this storm will be seen from the accompanying charts, 
numbers 6 to 13. I have called it one storm, though, perhaps, with more propriety, it 
might*be called several; for it is obvious that there was more than one centre of action 
On the first of February, at sunset, the storm was marshalling its forces. No rain had 
fallen, but clouds had formed in four different places, as seen by chart 6, in the north-east, 
north-west, south-east, and south-west parts of the United States, respectively. The 
chief of these was in the south-west, and from this, during the succeeding night, was 
discharged a torrent of rain. Chart 7 shows the condition of the storm the next morn- 
ing. ‘The north-east cloud had greatly expanded, but had yielded no rain. The north- 
west and south-east clouds had deposited a little rain; but the south-west cloud had 
poured down rain over a circle at least seven hundred miles in diameter. Before sunset 
of the second, the north-east cloud had expanded still farther, but without rain. The 
south-east cloud had ceased to rain; the north-west cloud had become blended with the 
south-west, and rain was now falling over an area about one thousand miles long by five 
hundred broad. Before morning of the third, rain burst forth in torrents from the north- 
east cloud, and united with the south-west, so that the area of rain was, at least, seven- 
teen hundred miles long, from south-west to north-east, and in its greatest breadth at 
least nine hundred miles. Upon the northern margin of the storm was a band of snow. 
Before sunset, this storm became broken into three considerable portions; the south-west 
being the largest. The clouds became somewhat broken, and in the north-east the rain 
was generally moderate, amounting, in many places, to a mere drizzle, and at others 
bringing a dense fog. Before the morning of the fourth, the storm became still farther 
broken into five small patches of rain, with numerous openings through which clear sky 
