4. It can not depend on the existence of tides in the atmosphere, since it must then correspond to lunar periods. Nor to accumulations of air from the specific levity of the upper regions of the atmosphere, since its degree of fluidity must correspond with its tenuity, and consequently such great mountains of air can not be supposed to exist for so many weeks together as the south west winds sometimes continue. 5. It remains therefore that there must be at this time a great and sudden absorption of air in the polar circle by some unknown operation of nature, and that the south wind runs in to supply the deficiency. Now as this south wind consists of air brought from a part of the earth's surface which moves faster than it does in this climate it must have at the same time a direction from the west by retaining part of the velocity it had previously acquired. These south-west winds coming from a warmer country, and becoming colder by their contact with the earth of this climate, and by their expansion, (so great a part of the superincumbent atmosphere having vanished,) precipitate their moisture; and as they continue for several weeks to be absorbed in the polar circle would seem to receive a perpetual supply from the tropical regions, especially over the line, as will hereafter be spoken of. It may sometimes happen that a north-east wind having passed over us may be bent down and driven back before it has acquired any heat from the climate, and may thus for a few hours or a day have a south-west direction, and from its descending from a higher region of the atmosphere may possess a greater degree of cold than an inferior north east current of air. The extreme cold of Jan. 13, 1709, at Paris came on with a gentle south wind, and was diminished when the wind changed to the north, which is accounted for by Mr. Homberg from a reflux of air which had been flowing for some time from the north. Chemical Essays by R. Watson, Vol. V. p. 182. It may happen that a north-east current may for a day or two pass over us and produce incessant rain by mixing with the inferior south-west current; but this as well as the former is of short duration, as its friction will soon carry the inferior current along with it, and dry or frosty weather will then succeed. NORTH-EAST WINDS. The north-east winds of this country consist of regions of air from the north, travelling sometimes at the rate of about a mile in two minutes during the vernal months for several weeks together from the polar regions toward the south, the mercury in the barometer standing above 30. These winds consist of air greatly cooled by the evaporation of the ice and snow over which it passes, and as they become warmer by their contact with the earth of this climate are capable of dissolving more moisture as they pass along, and are thence attended with frosts in winter and with dry hot weather in summer.