Humboldt, at Caraccas, in South America, has made ſome intereſting obſervations on the motion of the barometer near the equator. “I have read,” ſays he, “in the Tranſactions of the Bengal Society, that the barometer riſes and falls there regularly every 24 hours. Here, in South America , its motion is more aſtoniſhing. There are four atmoſpherical tides every 24 hours, which depend only on the attraction of the ſun. The mercury falls from 9 o’clock in the morning till 4 o’clock in the evening. It riſes from 4 till 11 o’- clock; it falls from 11 o’clock till half paſt four in the morning; it reaſcends from that time till 9 o’clock; neither winds, ſtorms, nor earthquakes, have any influence on this motion.” This fact goes a great way towards proving the general truth of Mr. Howard’s theory, given in the Philosophical Magazine, Vol. VII.