A long series of minute observations are necessary to determine positively whether the waters of the lake do or do not rise and fall periodically. It is well known, for instance, that in wet seasons the waters rise much above their ordinary level, and that in very dry seasons they sink considerably below it; a close attention, therefore, ought to be paid to the quantity of rain that falls, and to evaporation; and it ought to be ascertained in what degree the height of the lake is altered thereby; otherwise, if the lake happened to be higher or lower than usual on the seventh year, it would be impossible to say with accuracy whether it were owing to the state of the weather, or to certain laws of nature that we are yet unacquainted with. At the same time, great attention ought to be paid to the state of the winds, as well in respect to their direction as to their velocity, for the height of the waters of all the lakes is materially affected thereby. At Fort Erie, situated at the eastern extremity of the lake of the same name, I once observed the waters to fall full three feet in the course of a few hours, upon a sudden change of the wind from the westward, in which direction it had blown for many days, to the east-ward. Moreover, these observations ought not only to be made at one place on the borders of anyone of the lakes, but they ought to be made at several different places at the same time; for the waters have encroached, owing to some unknown causes, considerably and gradually upon the shores in some places, and receded in others. Between the stone house, in the fort at Niagara, and the lake, for instance, there is not at present a greater space than ten yards, or thereabouts; though when first built there was an extensive garden between them. A water battery also, erected since the commencement of the present war, at the bottom of the bank, beyond the walls of the fort, was sapped away by the water in the course of two seasons, and now scarcely any vestige of it remains. At a future day, when the country becomes more populous and more wealthy, persons will no doubt be found who will have leisure for making the observations necessary for determining whether the lakes do or do not undergo a periodical change, but at present the inhabitants on the borders of them are too much engaged in commercial and agricultural pursuits to attend to matters of mere speculation, which, however they might amuse the philosopher, could be productive of no solid advantages to the generality of the inhabitants of the country. [Sidenote: OBSERVATIONS.]