NORTHERN LIGHTS, the same with AURORA
BOREALIS, under which article we have given a co-
pious account of this phenomenon, and of the sup-
posed causes of it. Natural science, however, does not
arrive at perfection at once, and it is well if it does so
after trials repeated for years with care and accuracy.
How far the causes that have been assigned for this
appearance will account for it, or whether they will
be able to remove all difficulties, it is not for us to
determine; but it is the part of philosophers to hear
all sides, and to attend with patient attention to every
hypothesis, rejecting or receiving, as reason, after the
strictest investigation, shall seem to favour the one side
or the other. We shall here notice a hypothesis which
Doctor Stearns, an American, formed, about the year
1788, to account for the appearances called aurora bo-
realis, and aurora australis.
Doctor Stearns supposes that these phenomena ori-
ginate from aqueous, nitrous, sulphureous, bituminous,
and other exhalations, from the fumes of various kinds
of earths or other minerals, vegetables, animals, fires,
volcanoes, &c. These, he thinks, become rarefied,
and being charged with electrical fluid, become specifi-
cally lighter than the circumambient air; hence, of
course, they ascend; and being elevated to the upper
regions of the air, and driven by the winds from warm-
er to colder climates, the cold makes them combine
and stiffen. When they are afterwards agitated by dif-
ferent currents of air, they sparkle and crackle like the
hairs of cats and other animals when stiffened with cold.
This conflagration in quite cold atmospheres, and in those
which are more temperate, appears in different positions
in the horizon, zenith, or otherwise, according to the
situation of the spectator, and the position of the elevated
exhalations. The difference of colours the doctor sup-
poses to arise from the different qualities of the articles
combined, those of the most inflammable nature shining
with the greatest lustre.
The doctor likewise tries to account for these lights
not appearing, or but seldom appearing, in ancient
times. The atmosphere, he thinks, was not impreg-
nated with materials proper to produce them. He im-
agines that the increased consumption of fuel, in A-
merica in particular, the burning of volcanoes, and the
approach of blazing stars, whose atmospheres have been
so expanded by the sun's heat that part of them have
fallen into the earth's atmosphere, and communicated
to it new matter, have so changed and prepared our air,
that whenever its consistency is proper, then, if the light
of the sun and moon is not too powerful, the aurora
borealis will appear.