Alexandria gazette. [volume] (Alexandria, D.C.) 1834-1974, 1834-11-19
INDIAN SUMNER.

This delightful season, which sheds its happy
influences over the departing year, has attracted
far less, than might have been expected, the ad-
mration Of the poet or the research of the Phi
losopher. On this subject the Indians were in
fact more poetical than their civilized success
sors: for they attributed it to the kindness of a
benignant deity, whose abode was in that quar-
ter of the sky, whence the gentle southwestern
breezes come, which are one of the peculiar
characteristics Of the Indian summer. Indeed,
there are few who will undertake to say to what
month in the year It properly belongs; though a
native New Highlander would consider the year
as incomplete without it, as if the annual thanks
giving were omitted in the autumn. Every one,
however, knows and welcomes it when it arrives;
he knows it by its calm and hazy atmosphere,
its red sky, and its mild temperature; the last
quality is undoubtedly the one, from which a
portion of its appellation is derived; and he wei
comes it as short period Of respite from the
fearful reality of six months winter.-Boston
Daily Advertiser.
The last number ofProfessor Sman's Journ-
al contains an essay on the subject of the Indian
Summer, which was read at late meeting of
the Maryland Academy of Sciences and in
which the writer undertakes to explain the pro-
minent causes that concur in its production, and
some of the phenomena, by which 1t is attended
He fixes the period of its appearance in the
month of November; observing that the haZi-
ness Of the atmosphere which sometimes occurs
in October, induces many persons to mistake
the period of its occurrence for the true Indian
Summer. The leading cause to which he at
tributes it is a regular and extended variation
of temperature: the temperature in autumn is
rapidly on the decline, and slight addition to
the humidity of the atmosphere produces haZy
weather. second prominent cause is the pre-
vaence ofpeculiar winds: northwesterly wind,
bringing with it, from obvious causes small
supply of moisture, is attended with transpa-
rent atmosphere: while the reverse is occasioned
by south easterly winds. The third cause is the
elevation or depression of atmospherical strata;
this is most commonly produced by changes Of
at the surface of the earth, and by
electrical causes. During the warmer months,
these electrical causes produce an intermlxture
of the different currents OF air; but at the ap-
proach of winter, their energy is diminished,
and they suffer portions Of air, differing in tenn
perature and humidity, to remain without blend
ing with each other.
The formation of haze depends essentially on
a reduction Of atmospherical temperature, which
brings the water contained in the air to visi-
bic subvaporous state. This increased density
and is Immediately referrible to slow currents
or moist winds from southerly direction, usu.
ally succeeding dry westerly or northerly ones,
by which the temperature of the atmosphere
has been reduced When the moist current
comes in contact with dry northerly one, the
result is reduction of temperature, attended
with hazy or cloudy formation; the superior
str alum, which is westerly nortberly, remaining
meantime dry and cloudless. This is the condi-
49, oc th; d,,r ~ no nd
But why does the Indian sum mer make its ap-
pearance, at the close OF Autumn To this
question the writer replies as follows: within
the tropics the trade wind is constantly blowing
from east to west: without, the prevailing winds,
both to the south and north, are westerly. The
equilibrium, which is disturbed by the trade
winds, is thus restored. This westerly current
is counteracted during the summer, by opposite
winds arising from various causes; but in the au-
tumn it renewsits force, and continues atintervas
until its effect just mentioned has been produced,
and it is then succeeded by a southern reaction.
At this period. usually the last Of November,
occurs the Indian Summer.
The redness of the sky is one of the most re-
markable phenomena of this season. The wri-
ter explains this on the supposition, that the
white beam of light being unfolded in its pas
sage through the foggy stratum near the earth's
surface, its more delicate rays are reflected
back; or absorbed, while the stronger rays Of
red and orange penetrate to the surface, and
tinge with their own colour surrounding objects,
especially the lower atmosphere, which reflects
and refracts them in every possible direction
This redness, together with the irritation pro-
duced by the denseness of the aerial vapor, ex-
cites painful affection Of the eyes, Many per-
sons have been induced by this circumstance to
believe that the appearance is produced by
smoke; but this is an optical illusion. The in
creased temperature is to be attributed in part
to the prevailing wind, which is southerly, and
in part to the reflection back by the haze of the
atmosphere, Of the heat radiated from the
earth's surface, and the condensation of air
and moisture during tho formation of the foaox