That earthquakes are preceded _sometimes_ by a peculiar haziness and oppressiveness, similar to that which sometimes precedes a storm, is a current opinion in volcanic countries. And Humboldt, who doubts the connection, has to confess that sudden changes of weather have _succeeded_ violent earthquakes, and that "during the great earthquake of Cumana, he found the inclination of the needle was diminished 48′." He also mentions the simultaneous occurrence of shocks, from earthquakes, and a clap of thunder, and the agitation of the electrometer during the earthquake, which lasted from the 2d of April to the 17th of May, 1808; but concluding that "these indications presented by clouds, by modifications of atmospheric electricity, or by calms, cannot be regarded as _generally_ or _necessarily_ connected with earthquakes, since in Peru, Canada, and Italy, earthquakes are observed, along with the purest and clearest skies, and with the freshest land and sea breezes. But if no meteorological phenomena indicates the coming earthquake, either on the morning of the shock or a few days previously, the influence of certain periods of the year, (the vernal and autumnal equinoxes,) the commencement of the rainy season in the tropics, after long drought, cannot be overlooked, even though the genetic connection of meteorological processes, with those going on in the interior of our globe, is still enveloped in obscurity."[34] It is at the equinoxes that the earth changes her distances from the sun most rapidly, and whether she is passing from her perihelion or from her aphelion, the density of the ether externally is changing in the subduplicate ratio of these distances and consequently at these times there will be the greatest disturbance of the electric equilibrium. How far our views of the internal structure of our globe, (considered along a diameter as a solid crust, then a fused mass separated from the lower ocean by another solid crust, and separated from a similar arrangement on the opposite side by an interposed mass of water, perhaps also possessing a solid nucleus,) may affect this question, is difficult to say; but that the agent is electric, appears highly probable; and very recently it has been discovered, by M. Ratio Menton, that a piece of iron, suspended by attraction to a magnet, will fall on the approach of an earthquake; thus indicating that the power of the magnet is temporarily weakened by the action of some disturbing force. FOOTNOTES: [22] Hum. Cosmos, art Aerolites. [23] We shall in all cases use this abbreviation for the extremely awkward word zodiacal. [24] It is here assumed, that all the vortices are at their apogee at the same time, and, consequently, they lie in different longitudes, but the central being between, its position is taken for the average position of the three. [25] It is far from improbable that the effect produced in one zone of climate, may be reversed in another, from the nature of the cause.