REPORT ON METEOROLOGY. 
215 
indeed applies very well to observations made in the meridian 
of Europe. A more extended view of the subject, and a com¬ 
parison of the results of Captains Scoresby and Parry, showed, 
however, that there must exist two poles of maximum cold, one 
in America, the other in Asia, round which the isothermal lines 
circulate : and he has lately pointed out, in a letter to Baron 
Humboldt*, the remarkable analogy of these to the isodyna- 
mical lines of magnetic intensity, developed by Professor 
Hansteen. In a private letter dated 27th March 1830, Dr. 
Brewster communicated to me his new formula under this 
form, 
t = (T -f T ) • sin^ 5 • sin* S') + r, 
t being the mean temperature of a place of which the distance 
from the two cold poles is 8 and S': T the maximum tempera¬ 
ture of the globe, and t the minimum. In the meridian of 
maximum heat which passes through Europe S — S', and the 
formula becomes 
t = (T + t) . sin S + t, 
which nearly coincides with the formula T = 81°*5 cos L given 
above, and represents observations extremely well. I was 
much pleased to see a formula which took into consideration 
the actual distance j~ from the cold poles, because it had always 
struck me that the modifications of the isothermal lines depend¬ 
ing upon the accidental figure of the continental masses, it 
would be better to discard at once the arbitrary coordinates of 
latitude and longitude, the essential connexion of climate with 
the latter being nothing, and with the former modified by an 
infinity of perturbing causes. This seems, in the arbitrary for¬ 
mula just quoted, to be well effected by making the mean tem¬ 
perature a function of the distance from two imaginary poles of 
greatest cold. Perhaps the modifying circumstances produced 
by the physical geography of continents are too complex ever 
to enter expressly into a formula which should exhibit the re¬ 
lation of the temperature, as an effect, to its really active causes. 
Mr. Atkinson has published, in the Memoirs of the Astrono¬ 
mical Society J, an examination of the results of Humboldt’s 
researches, with a view to obtain an accurate expression for the 
law of climate. He has however considered it merely as a 
function of the latitude, which can never represent universally 
the phenomena. Plis equation 
t = 97-08 cos *1 - 10°-53 
* PoggendorfF’s Annalen, 1831 : i. 323. 
t By employing two distinct formulas for the two cold poles, Dr. Brewster, 
had before introduced the angle of simple distance. See Edvn. Trans, ix. 
t vol. ii. 
