Ce Eee oT) 
Terrestrial Magnetism. 103 
the rapid passage of one of the elements through the air, but with 
increased energy, for the element itself would enter into the com- 
bination. Still I contend that light and heat, or one of them, is 
the result of the combining of the fluids of either magnetism, elec- 
tricity, or galvanism, without the aid of any other body. This is 
shown by passing electricity through the exhausted receiver of 
an air pump, when we have beautiful displays of light, and the 
effect is the more striking, the more perfect the vacuum. — 
If there are three simple elements such as I have here supposed, 
two of which are the fluids on the poles of the loadstone; then 
‘let these three be so unequally diffused over and in the earth, as 
severally to predominate, one at or near the north pole, another at 
the magnetic equator, and the third at the south pole; each at- 
tracting the others, but repelling itself; and we have an elucida- 
tion of terrestrial magnetism. 
One of the elements entering into the constitution of light, 
but not necessary to heat, abounded in the arctic regions, so as to 
predominate in all: terrestrial forms to the exclusion of the ele- 
ments constituting heat, and this element is identical with one of 
the fluids on the poles of the loadstone, then it must follow, that 
the poles of greatest cold would coincide with the magnetic poles, 
and the isothermal lines have some accordance to the magnetic 
intensities of different latitude. 
The frequent occurrence of the aurora borealis in the northern 
tegions would be explained on this hypothesis, from one of the 
“onstituents of light predominating in the arctic circle ; and the 
ason of its affecting the needle be at once shown: so I think a 
Solution may be afforded, for the curious facts, that heat while it 
imparts the magnetic virtue to soft iron, diminishes with its in- 
‘tease the power of the loadstone; while a white heat entirely 
destroys it, and a red heat reverses the poles. 
T admit that these views are merely hypothetical, but they are 
a more extended theory, which runs its ramifications 
through all the phenomena of nature, according with so many 
facts, that I cannot regard it as merely visionary ; but I admit 
that much deliberation and caution are requisite in advancing such 
Pesitions, lest we should disturb science with unfounded specula- 
ions, 
