So much for popular beliefs. Quite generally there are subterranean rumblings, or slight tremors preceding the more violent shock; but even these are not sure signs, as they may occur alone, or the earthquake may come unannounced. A notable case of the former sort is the remarkable subterranean roaring heard at Guanaxuato, in Mexico, in 1784. It lies in a rich mining district, with no volcano in the vicinity. On January 9 there broke out, after some preliminary muttering, a great uproar which seemed as if a thunder storm were going on beneath the surface of the earth. A short distance from the town it could not be heard; and not the slightest tremor of the soil was perceptible, even in mines sixteen hundred feet deep. But so great was the panic it created, that thousands fled from the town, leaving it entirely to the mercy of thieves and bandits. The alcaldes, with true Spanish grandiloquence, asserted that the government would “be able in its wisdom to say when danger is imminent, and to take measures for enabling the people to fly for refuge;” and it determined to impose a penalty of one thousand piasters on the rich, or of two months imprisonment on the poor who fled ere the word was given. But though it was easy to make laws, it was not so easy to feed the people; for the affrighted peasantry would not set foot in the city; so the month of uproar became one of famine as well. [Illustration: HOUSES THROWN INTO A RAVINE BY AN EARTHQUAKE.] A similar rumbling occurred in Melada, an island off the coast of Dalmatia, in 1822, and the frightened inhabitants besought the Austrian government to transport them to a place of safety; but though the explosions continued during two years, sometimes more than one hundred in a single night, nothing ever resulted therefrom. So with regard to all popular beliefs on this topic--no dependence can be placed on any of them. There is nothing to warn us of the approach of the earthquakes, neither in the heavens above, nor the earth beneath, nor the waters under the earth. Has the reader ever experienced one of these strange earthstorms? Perhaps not. Is it believed they are rare? They are as common as storms in the atmosphere. Within a period of seven years, four thousand six hundred and twenty have been recorded. Many more, doubtless, occurred completely beyond the pale of civilization. Hundreds have passed unnoticed save by delicate instruments. Not a day passes without several being recorded. They are as widely various in power as the storm and the breeze. Not a region on earth is unvisited by them.