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The general belief ot men respecting the cause of earthquakes, is the igneous theory; in other words, they believe the centre of the earth is a molten mass, and that it is some times agitated, causing volcanoes and earth quakes. Those who entertain this belief have ingeniously strung together a great number of facts to prove that volcanic eruptions and earthquakes, are in general simultaneous and confined to the same localities. This, how ever, is not so, for many earthquakes take place when and where there are no volcanic eruptions. A correspondent of the "London Mining Journal," named Drummonds writing from Comrie, in North Britain, presents a theory entirely different Irom that of igneous action j he attributes earthquakes to electrical influ-encp, and we believe that Sir Charles Lyell has expressed a belief in the same agency.— Mr. Drummond resides in a district where many shocks of earthquakes are felt every year, and some of them have been so severe as to overthrow houses. The place is a high land village in the bosom of a mountainous country, and the shocks a never ielt at many miles from it, hence it must be the cen tre of the earthquake's influence. He states that no shocks have*liver been felt during easterly or westerly winds. All earthquakes th.st took place there were preceeded within 24 hours by much wind and :ain, but they have taken place oftenest in dull, thick, wet weather. The shocks were not felt alike in the same district; the houses which suffered most were built on wet places, no houses built on a depth of dry soil suffered. The earth quakes that have occurred when the weather was dry, were more abrupt, and of greater ve locity than those which took place in wet weather. They have oiten taken place when there were two currents of wind in the at mosphere, one moving contrary to the other. During all the great earthquakes, vast quanti ties of aqueous vapors were in the lower re gions of the air, which shows that vapor has much to do with the cause of earthquakes, j and Mr. Drummond considers it the medium j through which electricity acts to produce the I quaking phenomenon. The earthquakes commenced in that place in 1788, when a magnetic rock was opened up into a quarry for free stones. This has been opened and worked two or three times and it has been observed that according to its exposure by the quarrymen, so was the frequency of earthquakes increased. When shut up they decreased, and ceased fora while altogether, from 1809 to 1817. The rock was then worked again, and the earthquakes com menced their old tricks again. The quarry was again closed, and the earthquakes almost ceased, until it was opened again in 1834, and worked to a far larger extent than ever, ex posing a great amount of the magnetic rock surface. The earthquakes, during this time, became fearful and continued to do so, until 1846, when i was shut up, and they have now assumed a milder form. Sounds are of ten heard in the mountains like central ex plosions of artillery. Recent accounts from India inform us that some terrible earthquakes have taken place there; they continued for two weeks, the | earth heaving like the billows of the ocean. Earthquakes frequently take place at a great distance from volcanoes, at periods when no I volcanic eruption precedes, corresponds with,; or follows after. The igneous theory may be I true, but it certainly does not account for all j earthquakes, and Mr. Drummond says, " I j might as well try to submerge the British! Isles as to attempt the solution of the earth-1 quake problem upon the hypothesis of its being | the effects of molten matter in the interior of ! the earth." |
