d this seems to be the general law in summer in the Mississippi
valley, where the easterly winds are not so common as with us. To
illustrate this further, I copy from a recent work by T. Bassnett,
entitled the "Mechanical Theory of Storms," two short extracts, showing
the manner in which belts of showers extend southerly, while progressing
north-eastwardly, at Ottawa. The first occurred in August, 1853; the last,
December, 1852. The first was a belt of showers; the latter would have
been in August, but the lateness of the season changed its character
somewhat, though not entirely, to a more regular rain, especially toward
the close.

"AUGUST 6th.--Very fine and clear all day: wind from S. W.; a light
breeze; 8 P.M. frequent flashes of lightning in the northern sky; 10
P.M., a _low bank of dense clouds in north_, fringed with cirri,
visible during the flash of the lightning; 12 P.M., same continues.

"7th.--very fine and clear morning; wind S. W. moderate; noon, clouds
accumulating in the northern half of the sky; _wind fresher_, _S.
W._; 3 P.M., a clap of thunder over head, and black cumuli in west,
north, and east; 4 P.M., much thunder and scattered showers; six
miles west rained very heavily; 6 P.M., the heavy clouds passing over
to the south; 10 P.M., clear again in north.

"8th.--Clear all day; wind the same (S. W.); a hazy bank visible all
along on _southern horizon_.

"DECEMBER 21st, 1852.--Wind N. E., fine weather.

"22d.--Thick, hazy morning, wind east, much lighter in S. E. than in
N. W.; 8 A.M., a clear arch in S. E. getting more to south; noon,
_very black in W. N. W._; above, a broken layer of cirro-cumulus, the
sun visible sometimes through the waves; wind around to S. E., and
fresher; getting thicker all day; 10 P.M., _wind south, strong_;
thunder, lightning, and heavy rain all night, with strong squalls
from south.

"23d.--Wind S. W., moderate, drizzly day; 10 P.M., wind west, and
getting clearer."

It is obvious that the showers at the north passed east on the evening of
the 6th of August; that new showers, taking the same course, originated in
the north, but more southerly next day, with S. W. wind, and that they
passed east, and others formed successively further south, which passed
over the place of observation late in the afternoon, and that others
formed south and passed east during t