further illustration, when Quebec feels the force of the storm, Chicago
is at its extreme western limit. This supposed course will convey the
general idea of the track of a northeaster when it envelops the whole
variable-climatic district of the Union. There is a singular eddy known
to all climatologists to exist in Iowa, where the annual precipitation
of water is great, exceeding that of all the surrounding States. There
has been no positive theory advanced, to our knowledge, explaining this
circumstance, but the mystery is solved, to our minds, quite clearly.
This eddy makes the key-point of contact of the humid Gulf winds with
the cool winds of the westerly current, and likewise being the
northwestern terminal point of the course of the great northeasters,
the contact being the cause of the excess in precipitation. We were
fortunate, while visiting last autumn this special wet district of Iowa,
to experience one of these triangular storms. We were at Dubuque while
the wind was blowing gently from the south-southwest, with low
scattering clouds, and before night it began to thicken and rain, while,
in the night, the wind shifted to the east, blowing the rain briskly
before it. This continued a part of the following forenoon, when, taking
the train west to Rockford, northwest of Dubuque, we reached nearly the
edge of the easterly storm, which had been here simply a drizzling rain.
The next day the rain had ceased, the wind had shifted to the northwest,
rapidly drying the earth, and the clouds, both of the upper and lower
strata, were all driving hurriedly east-southeast. We left the following
day for Fort Dodge and Sioux City. At the former place they had had a
slight shower only, with shifting winds; while at Sioux City not a
particle of rain had fallen, the roads being not only dry but quite
dusty. This was not a merely local storm, but was the only great
easterly one covering any extent of territory and time, answering to the
equinoctial, which visited the United States during last autumn.