Now although this hypothesis explains the phenomena, it has still met with great opposition. The motions which Lieut. Maury supposes can hardly be accounted for without resorting, as is usual in such cases, to electricity or magnetism,--to some occult cause, or some occult operation of a known cause. Moreover, it has been difficult for the mechanical philosopher to understand how the winds manage to cross each other, as Lieut. Maury supposes them to do, at the equator and the tropics, without getting into "entangling alliances." If this hypothesis were advanced, not as a physical explanation of the phenomena, but, like the epicycles and eccentrics of Ptolemy, "to save the appearances," its ingenuity would be greatly to its author's credit; but, like the epicycles and eccentrics, though it represents the phenomena well enough, it contradicts laws of motion, now well known, which ought to be familiar to every physical philosopher. But these speculations of Lieut. Maury will now be superseded by a new theory of atmospheric movements, an account of which was presented by its author, Mr. J. Thompson, at the recent meeting of the British Association for the Advancement of Science. [1] [Footnote 1: A fuller discussion of this theory the author reserved for the Royal Society. The _London Athenaeum_ gives a brief abstract of his paper, in its report of the proceedings of the Association.] Mr. Thompson's theory takes account of forces, hitherto unnoticed, which are generated by the eastward circulation of the atmosphere in high latitudes. He shows that these forces cause the prevailing northeastward under-current of our latitudes, while above this, yet below the highest northeastward current, the air ought still to move southward according to Halley's theory.