100 Terrestrial Magnetism. 
Arr. IX.—Terrestrial Magnetism ; by J. Hamuron of Carlisle, 
, Penn. 
In the 22d volume of this Journal 1 suggested the idea, that 
the magnetic poles coincided with the coldest points in the north- - 
ern hemisphere, but did not assign the grounds for such a con- 
clusion. : 
In 1837, Dr. Brewster published his Treatise on Magnetism at 
Edinburgh, originally prepared for the Encyclopedia Britanica, 
which contains very full details of the latest researches on that 
subject. ; 
In the 42d page of this Treatise it is stated, ‘the discovery of 
two poles of maximum cold on opposite sides of the north pole of 
the earth, which was announced by Sir David Brewster in 1820, 
led him and other authors to the opinion, that there might be 
some connection between the magnetic poles, and those of maxti- 
mum cold.” The opinion advanced by Dr. Brewster, “ that there 
are two poles of greatest cold in the northern hemisphere,” it ap- 
_ pears, was published in the 9th volume of the Edinburgh ‘Trans- 
actions of 1821, and Dr. Dalton in remarking on it, considers it as 
a probable supposition, and Mr. Kupffer in a memoir read in 1829 
to the Russian Academy, explicitely adopts the opinion. 
Of all this I knew nothing when I wrote the letter above re- 
ferred to in 1832, nor until I met with Dr. Brewster’s Treastise 
published in 1837; but drew the inferences therein stated, from 
the views I entertained of the nature of light and heat,* and from 
observing a certain correspondence of climate at similar distances. 
from the magnetic poles. 
I regard light and heat 77 the comvmon acceptation of these words, 
as not only material in their nature, but as compounds of othet 
simple elements, and suppose the magnetic fluids to be two of 
those simple substances which enter into their constitution. 
From the refined nature of light and heat, we cannot subject 
them to experiment like other forms of matter, and the difficulty 
would necessarily be increased, if we have to do with the simple 
elements of which they are here supposed to be compounded. 
That matter exists in such states of refined minuteness of 
atoms, as to be imperceptible to such senses as we possess, }§ 
: i the word “ heat” I always mean sensible heat, and not the unknown prin 
ciple. 
“he 
