Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 13, MAT-MIC

and that of latitude 50°, 52.90. The fquare of the fine of 40° is nearly 0.419, and the fquare of the fine of 50*
is nearly 0.586. Therefore,
m—0.41 «=62.i, and
tn—0.58 »—52.9 $ therefore, '
62.1 -f-0.41 «=52.9-)-058 «,
as each of them, from the two firft equations, is equal to m. From this laft equation the value of n is found to
be nearly 53 •, and tn is nearly equal to 84. The mean temperature of the equator, therefore, is 84°, and that of
the pole 3 To find the mean temperature for every other latitude we have only to find 88 arithmetical means
between 84 and 31.
(e) In calculating the table of mean monthly temperature. Dr Kirwan proceeded on the following principles.
The mean temperature of April feems to approach very nearly to the mean temperature of the whole year, and
as far as heat depends on the adion of the folar rays, the mean heat of each month may be confidered as propor¬
tional