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.