2. There seem to exist only two original winds: one consisting of air brought from the north, and the other of air brought from the south. The former of these winds has also generally an apparent direction from the east, and the latter from the west, arising from the different velocities of the earth's surface. All the other winds above described are deflections or retrogressions of some parts of these currents of air from the north or south. 3. One fifteenth part of the atmosphere is occasionally destroyed, and occasionally reproduced by unknown causes. These causes are brought into immediate activity over a great part of the surface of the earth at nearly the same time, but always act more powerful to the northward than to the southward of any given place; and would hence seem to have their principal effect in the polar circles, existing nevertheless though with less power toward the tropics or at the line. For when the north-east wind blows the barometer rises, sometimes from 281/2 inches to 301/2, which shews a great new generation of air in the north; and when the south-west wind blows the barometer sinks as much, which shews a great destruction of air in the north. But as the north- east winds sometimes continue for five or six weeks, the newly-generated air must be destroyed at those times in the warmer climates to the south of us, or circulate in superior currents, which has been shewn to be improbable from its not depositing its water. And as the south-west winds sometimes continue for some weeks, there must be a generation of air to the south at those times, or superior currents, which last has been shewn to be improbable.