the same with AURORA BOREALIS, under which article we have given a copious account of this phenomenon, and of the supposed 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 assiduity to every hypothesis, rejecting or receiving as reason, after the strictest investigation, shall seem to favour the one side or the other. Wishing to lay before our readers everything important either in science or in literature, we cannot let pass the opportunity which the present article affords us, of mentioning an hypothesis which Doctor Stearns, an American, formed, about the year 1788, to account for the appearances called aurora borealis, and aurora australis. For this last, see AURORA BOREALIS, no. 3.

Doctor Stearns supposes that these phenomena originate 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 specifically 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 warmer to colder climates, the cold makes them combine and stiffen. When they are afterwards agitated by different currents of air, they sparkle and crackle like the hairs of cats and other animals when stiffened with cold. This congelation in quite cold atmospheres, spheres, 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 supposes 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 impregnated with materials proper to produce them. He imagines that the increased consumption of fuel, in America 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 confluence is proper, then, if the light of the sun and moon is not too powerful, the aurora borealis will appear.