IN THE MONTH OF FEBRUARY, 1842. 1v7 
Between these easterly and westerly winds we find a region of calms marked on the chart. 
The formation of the north-east cloud I suppose to be as follows. The pressure of the 
atmosphere was greater near the Atlantic than towards Lake Ontario. This must give 
a check to the north-west wind from the lake, causing a part of it to glance upward, 
forming cloud. The probability of this explanation will be seen from chart 7, where the 
cloud is much extended, and the winds are generally blowing from the south. The 
same causes produced a north-east wind on the south-east border of the United States, 
which, being opposed to wind from the gulf, formed cloud. By the morning of the 
second, these clouds were all partially united. The south-west pours down rain. The 
winds are generally westward on the west border, and eastward on the east border. The 
thermometer has risen a little, and the barometer fallen .2 inch. No sudden fall could be 
expected, considering the great extent of the storm. The north-west cloud seems almost 
to have lost its distinct existence; but in the north-east the winds are blowing from the 
region of greatest pressure, and cold towards the cloud. The south-east cloud had 
already deposited a little rain. ‘The barometer, in New England, continued to rise, not- 
withstanding the drain of air by the southerly winds. The air over the St. Lawrence 
being expanded, swelled up, overflowing New England, and more than compensating for 
the drain of the lower current. At sunset we find the same causes in operation. ‘The 
barometer had fallen .6 inch below the mean in the valley of the Mississippi, and this 
may be regarded as the principal centre of the storm. ‘The winds are now southerly 
throughout almost the entire United States. The cloud along the valley of the St. Law- 
rence was now greatly expanded, and ready to pour down rain. Its temperature had 
risen 20° above the mean. The winds on the south were blowing directly towards it, and 
probably also on the north. It might be expected that the winds would blow from every 
quarter towards the barometric minimum near St. Louis. In point of fact, the south-east 
winds extended much farther north. No doubt, however, north-west winds prevailed at 
a considerable distance northward, and they showed themselves with great force within 
the United States on the morning of the fourth. But the storm evidently extended in a 
north-west direction much beyond the limits of the United States, and the irregularities 
of the wind are owing to the fact, that the pressure and temperature were so nearly uni- 
form over so large a territory. On the morning of the third the north-east cloud had 
discharged its contents. The reason that this rain was so long in falling, (more than a 
day from the first formation of the cloud,) probably was, that the condensed vapour was 
frozen and the cloud was one mass of snow. The heat liberated by the continued con- 
densation and by the transfer of air from a lower latitude, in time melted it, and it fell in 
a general deluge. ‘The diminution of pressure in the vicinity of Lake Erie is now quite 
noticeable, being .6 inch below the mean, and the temperature has risen 30° above the 
mean; so that this is now the principal centre of the storm, and the north winds are now 
showing themselves at Montreal and Fort Kent. By sunset of the third, the clouds had 
become somewhat broken, and the rain had entirely ceased at some places, while it was 
reduced to a mere drizzle at others. We now see a general tendency of the wind inward 
from all the borders of the United States. On the south border the winds are, without 
exception, from the south; on the south-west they are from th 
border they are from the north. ‘This is a necessary consequence © 
VOL. 1X.—48 
e west, and on the north 
f the elevated tempe- 
