It would be difficult to form a conception of any thing in meteorology, more sublime than the aerial lightning of this climate. In dark nights the phenomenon is highly entertaining to every spectator to whom the appearance is new. The vivid flashes seem to emanate from a point, and diverge from thence in every possible direction. The eye has scarcely time to trace the progress of these coruscations, which seem to sweep round half the expanse of the heavens almost in an instant, and to irradiate {219} the margins of the blackest clouds with a transitory blaze. I have never seen the aurora borealis in America. Two instances of its appearing in 1814 are mentioned in the Picture of Cincinnati, which are supposed to be the only unequivocal ones observed since the settlement of the western country. This meteor is more frequently seen by the people of the northern States. The most prominent characteristics of the climate of this country are, the superior transparency of the air in clear weather; the frequency of a light yellow, but translucent tinge that is strongest at the horizon, and fainter upwards, where it is blended with a sky of a fine light blue, at the height of a few degrees. The number of foggy days is small,[122] and the appearance of clouds, previous to rain, sudden. Indeed, on several occasions, I have observed a clear atmosphere transformed into one abounding with dark clouds and rain, in the space of an hour. Changes of this kind are no doubt produced by sudden transitions of temperature. Severe gales of wind do not appear prevalent in western America, if the two last winters can be admitted as sufficient examples, as these seasons were much less stormy than those of Scotland. But it is necessary to make an exception of the tornadoes, which occasionally blow down houses, lay waste fields, and open avenues through the woods. One of these tempests destroyed some {220} buildings at Cincinnati, on the 28th of May, 1809. It was preceded by a wind from the south, and a higher current blowing from the west, and was understood to commence in the State of Tennessee. It crossed the Allegany mountains “and made its exit from the continent” on the same day.[123]