The Aurora Borealis or Northern Lights. 291 
At some remarkable periods when it has assumed its most 
terrific forms, something strongly resembling the electric 
chain of the thunder cloud has been observed: If we add to 
these facts, the late discoveries of the French philosophers, of 
the effects of those lights on the magnetic needle, there can 
be little doubt as to the nature of the agent that produces 
the northern lights. The next question; How comes there 
c 
thern pole, and by what means does it ascend to produce the 
alleged effect—is an enquiry of vastly more difficult solution, 
and on the correct and clear explanation of the causes pro- 
ducing these effects, depends the whole of this hypothesis. 
efore I proceed farther in developing the theory, I would 
remark, that the different kinds of minerals, although found 
combined with others, in various forms, and scattered by the 
convulsions of nature, over the whole globe, still abound 
(whether agreeably to some established law, I will not pre- 
tend to decide,) in particular regions, and are in a great meas- 
ure absent from other regions. For instance, gold, silver, pla- 
tina and quick silver, although found in other zones, are partic- 
ularly abundant in the tropical regoins ; copper, lead and tin. 
occupy the latitudes next north; iron, fetes meteoric,) is the 
native product of the northern regions. In the- I 
cussion of this subject, I shall assume as historically true, the 
ollowing mineralogical! facts. First, that south of the equa- 
tor, there are not to be found any considerable masses of iron 
under any form; our knowledge as to the mineralogy of a 
portion of those regions, is admitted to be extremely limited. 
So far as those regions on this continent have been explored 
by Humboldt and other modern travellers, no masses of this 
mineral have been discovered, nor as far as our knowledge 
extends, have we any reason to believe, that any such mass- 
es are to be found on the eastern continent. The next fact 
assumed is, that no great masses of iron, are to be found 
within 32° north of the equator; that near that point the 
iron region commences and era northerly as far as 
es of north latitude. As to all purposes of this discus- 
sion, this iron region may be considered, as a world by 
itself, and the centre of electrical attraction, in other words, 
the theory is this, that the electric fluid is gradually drawn off 
from the clouds and incumbent atmosphere by the peaks of 
