56 98
Mean temperature for 1820 56 18

The mean of these results is about fifty-six degrees and a quarter.

The mean temperature of each month during the above years, is as
follows:

Deg. Hund.
January 30 62
February 38 65
March 43 13
April 58 47
May 62 66
June 74 47
July 78 66
August 72 88
September 70 10
October 59 00
November 53 13
December 34 33

The mean temperature of the different seasons is as follows:

Winter, 34.53--Spring, 54.74--Summer, 74.34--Autumn, 60.77.

The greatest extremes of heat and cold during my residence of eighteen
years, in the vicinity of St. Louis, is as follows:

Greatest heat in July 1820, and July 1833, 100 degrees. Greatest cold
January 3d, 1834, 18 degrees below zero,--February 8th, 1835, 22
degrees below zero.

The foregoing facts will doubtless apply to about one half of Illinois.
This climate also is subject to sudden changes from heat to cold; from
wet to dry, especially from November to May. The heat of the summer
below the 40 deg. of latitude is more enervating, and the system becomes
more easily debilitated than in the bracing atmosphere of a more
northerly region.

At Marietta, Ohio, in lat. 39 deg. 25' N. and at the junction of the
Muskingum river with the Ohio, the mean temperature for 1834, was 52
degrees, four-tenths; highest in August, 95 degrees,--lowest, January,
at zero. Fair days 225,--cloudy days 110.

At Nashville, Tenn. 1834, the mean temperature was 59 degrees and
seventy-six-hundredths; maximum 97, minimum 4 above zero. The summer
temperature of this place never reaches 100 deg. On January 26th, 1832,
18 degrees below zero. February 8th, 1835, 10 deg. below zero.

The putting forth of vegetation in the spring furnishes some evidence of
the character of the climate of any country, though by no means entirely
accurate. Other causes combine to advance or retard vegetation. A wet or
dry season, or a few days of heat or cold at a particular crisis, will
produce material changes.

The following table is constructed from memoranda made at the various
dates given, near the latitude of St. Louis, which is computed at 38 deg.
30'.