Those elements which represent the moon's distance and motion are accurately known, and may be taken from the Nautical Almanac, being all embodied in the moon's parallax or semi-diameter, and in the declination and right ascension; but for the most important element,--the moon's mass, we in vain look to astronomy. In fact, it may be averred that the importance attached to astronomical authority, concerning the mass of the moon, has caused more trouble than any other question of the whole theory, until we trusted implicitly to the theory itself to determine it. The determination of three unknown elements, viz.: the moon's mass, the inclination of the axis of the vortex, and the right ascension of that axis, is a more difficult problem than at first sight appears, owing to the nature of the phenomena, which affords the only clue for its solution. There are six principal vortices ever in operation on the surface of the earth, and their disturbing influence extends from 200 to 400 miles. To find the precise centre, by one observer confined to one place, is difficult; and to separate them, so as to be fully assured that you have the right one, is perhaps still more so. Happily this tedious labor is accomplished, and we are able with confidence to give the following important elements, as very close approximations to the truth: Mass of the moon 1/72.3 Obliquity of the axis of the vortex 15° to 32° variable. Right ascension of ditto 250° to 290° variable. It must be borne in mind that we are now discussing the main or central vortex of the earth; but before applying them to the calculation, we will explain the _modus operandi_, waiving for the present the consideration of the law of density in the Terral vortex. It is evident at first sight that if the periodic times of the parts of the vortex contiguous to the moon, are equal to the moon's period approximately, that the velocity of the ether is greater at the surface of the earth than the velocity of that surface. Now, we have before argued that the ether possesses inertia, it therefore would under such circumstances exert some mechanical action. Consequently, the aërial envelope of our globe, or its superior stratum, is impelled eastward by _convection_[4] of the more rapidly rotating ether. And from the extreme tenuity of its upper layers, is probably forced into immense waves, which will observe to a certain degree, a general parallelism north and south. ATMOSPHERIC CURRENTS.