arrested, on a calm day, by the earth heaving and rocking beneath their feet; and in a few moments two hundred and fifty thousand of them are buried by falling houses, or the earth opening and swallowing them up. Such was the scene which that city presented in the year 526; and several times before and since that period has the like calamity fallen upon it; and twenty, forty, and sixty thousand of its inhabitants have been destroyed at each time. In the year 17 after Christ, no less than thirteen cities of Asia Minor were in like manner overwhelmed in a single night. Think of the terrible destruction that came upon Lisbon in 1755. The sun had just dissipated the fog in a warm calm morning, when suddenly the subterranean thundering and heaving began; and in six minutes the city was a heap of ruins, and sixty thousand of the inhabitants were numbered among the dead. Hundreds had crowded upon a new quay surrounded by vessels; in a moment the earth opened beneath them, and the wharf, the vessels, and the crowd went down into its bosom; the gulf closed, the sea rolled over the spot, and no vestige of wharf, vessels, or man ever floated to the surface. How thrilling is the account left us by Kircher, who was near, of the destruction of Euphemia, in Calabria, a city of about five thousand inhabitants, in the year 1638! "After some time," says he, "the violent paroxysm of the earthquake ceasing, I stood up, and, turning my eyes to look for Euphemia, saw only a frightful black cloud. We waited till it had passed away, when nothing but a dismal and putrid lake was to be seen where the city once stood." In like manner did Port Royal, in the West Indies, sink beneath the waters, with nearly all its inhabitants, in less than one minute, in the year 1692. Still more terrific have been some of the eruptions in Iceland. In 1783, earthquakes of tremendous power shook the whole island, and flames burst forth from the ocean. In June these ceased, and Shaptar Jokul opened its mouth; nor did it close till it had poured forth two streams of lava, one sixty miles long, twelve miles broad, and the other forty miles long, and seven broad, and both with an average thickness of one hundred feet. During that summer the inhabitants saw the sun no more, and all Europe was covered with a haze. Around the Papandayang, one of the loftiest mountains in Java, no less than forty villages were reposing in peace. But in August, 1772, a remarkable luminous cloud enveloping its top aroused them from their security. But it was too late. For at once the mountain began to sink into the earth, and soon it had disappeared with the forty villages, and most of the inhabitants, over a space fifteen miles long and six broad. Still more extraordinary, the most remarkable on record, was an eruption in Sumbawa, one of the Molucca Islands, in 1815. It began on the fifth day of April, and did not cease till July. The explosions were heard in one direction nine hundred and seventy miles, and in another seven hundred and twenty miles. So heavy was the fall of ashes at the distance of forty miles that houses were crushed and destroyed. The floating cinders in the ocean, hundreds of miles distant, were two feet thick, and vessels were forced through them with difficulty. The darkness in Java, three hundred miles distant, was deeper than the blackest night; and finally out of the twelve thousand inhabitants of the island, only twenty-six survived the catastrophe. Now, if we confine our views to such facts as these, we can hardly avoid the conclusion that earthquakes and volcanoes are terrific exhibitions of God's displeasure towards a fallen and guilty world. But if it can be shown that the volcanic agency exerts a salutary influence in preserving the globe from ruin, nay, is essential to such preservation, we must regard its incidental destruction of property and life as no evidence of a vindictive infliction, nor of the want of benevolence in its operation. And the remarkable proofs which modern geology has presented of vast accumulations of heated and melted matter beneath the earth's crust, do make such an agent as volcanoes essential to the preservation of the globe. In order to make out this position, I shall not contend that all the earth's interior, beneath fifty or one hundred miles, is in a state of fusion. For even the most able and decided of those geologists who object to such an inference, admit that oceans of melted matter do exist beneath the surface. And if so, how liable would vast accumulations of heat be, if there were no safety-valves through the crust, to rend asunder even a whole continent? Volcanoes are those safety-valves, and more than two hundred of them are scattered over the earth's surface, forming vent-holes into the heated interior. Most of them, indeed, have the valves loaded, and the effort of the confined gases and vapours to lift the load produces the terrific phenomena of earthquakes and volcanoes. But if no such passages into the interior existed, what could prevent the pent-up gases from accumulating till they had gained strength enough to rend a whole continent, and perhaps the whole globe, into fragments? Is it not, then, benevolence by which this agency prevents so dreadful a catastrophe, even by means that bring some incidental evils along with them? This is certainly the case in regard to volcanoes. We have strong reason to believe that they are essential to the preservation of the globe; and of how much higher consequence is this than the comparatively small amount of property and life which they destroy! If we can only rise to these higher views, and not suffer our judgment to be warped by the immediate terrors of the earthquake and the volcano, we shall see the smile of infinite benevolence where most men can only see the wrath of an offended Deity. DISCOVERY AND USE OF THE BAROMETER. (From Arnott's " Elements of Physics.") At'mos-phere,n.(Gr.atmos,sphaira)| 2 left open,and immerged in a small basin of quicksilver or mercury. Its uses are to indicate changes in the weather, to determine the height of mountains &c., by the falling or rising of the mercury. Fluc'tu-ate, v. (L. fluctus), to roll hither and thither; to be unsteady. Mon'i-tor, n. (L. moneo), one who omen. GALILEO1 had found that water would rise under the piston of a pump to a height only of about thirty-four feet. His pupil Torricelli, conceiving the happy thought that the weight of the atmosphere might be the cause of the ascent, concluded that mercury, which is about thirteen times heavier than water, should only rise under the same influence to a thirteenth of the elevation: he tried, and found that this was so, and the 1 Galileo, a famous astronomer, born at Pisa, 1564. He invented the Thermometer, Telescope &c. 2 Torricelli, of Florence, invented the Barometer, 1643. mercurial barometer was invented. To afford further evidence that the weight of the atmosphere was the cause of the phenomenon, he afterwards carried the tube of mercury to the tops of buildings and of mountains, and found that it fell always in exact proportion to the portion of the atmosphere left below it; and he found that water-pumps, in different situations, varied as to sucking power, according to the same law. It was soon afterwards discovered, by careful observation of the mercurial barometer, that even when remaining in the same place, it did not always stand at the same elevation; in other words, that the weight of atmosphere over any particular part of the earth was constantly fluctuating: a truth which, without the barometer, could never have been suspected. The observation of the instrument being carried still further, it was found that in serene dry weather the mercury generally stood high, and that before and during storms and rain it fell; the instrument, therefore, might serve as a prophet of the weather, becoming a precious monitor to the husbandman or the sailor. When water, which has been suspended in the atmosphere, and has formed a part of it, separates as rain, the weight and bulk of the mass are diminished; and the wind must occur when a sudden condensation of aeriform matter, in any situation, disturbs the equilibrium of the air, for the air around will rush towards the situation of diminished pressure. To the husbandman the barometer is of considerable use, by aiding and correcting the prognostics of the weather which he draws from local signs familiar to him; but its great use as a weather-glass seems to be to the mariner, who roams over the whole ocean, and is often under skies and climates altogether new to him. The watchful captain of the present day, trusting to this extraordinary monitor, is frequently enabled to take in sail, and to make ready for the storm, where, in former times, the dreadful visitation would have fallen upon him unprepared-the marine barometer has not yet been in general use for many years, and the author was one of a numerous crew who probably owed their preservation to its almost miraculous warning. It was in a southern latitude. The sun had just set with placid appearance, closing a beautiful afternoon, and the usual mirth of the evening watch was proceeding, when the captain's order came to prepare with all haste for a storm. The barometer had begun to fall with appalling rapidity. As yet the oldest sailors had not perceived even the threatening in the sky, and were surprised at the extent and hurry of the preparations; but the required measures were not completed, when a more awful hurricane burst upon them than the most experienced had ever braved. Nothing could withstand it; the sails, already furled and closely bound to the yards, were riven away in tatters; even the bare yards and masts were in great part disabled, and at one time the whole rigging had nearly fallen by the board. Such, for a few hours, was the mingled roar of the hurricane above, of the waves around, and of the incessant peals of thunder, that no human voice could be heard, and, midst the general consternation, even the trumpet sounded in vain. In that awful night, but for the little tube of mercury which had given warning, neither the strength of the noble ship, nor the skill and energies of the commander, could have saved one man to tell the tale. On the following morning, the wind was again at rest, but the ship lay upon the yet heaving waves, an unsightly wreck. The marine barometer differs from that used on shore, in having its tube contracted in one place to a very narrow bore, so as to prevent that sudden rising and falling of the mercury, which every motion of the ship would else occasion. Civilized Europe is now familiar with the barometer and its uses, and, therefore, they almost require to witness the astonishment or incredulity with which people of other parts regard it. A Chinese once conversing on the subject with the author, could only imagine of the barometer that it was a gift of a miraculous nature, which the God of Christians gave them in pity, to direct them in the long and perilous voyages which they undertook to unknown seas. 1. Tell me something about Galileo and Torricelli. 2. To what height can water be made to rise in a pump? 3. What happy thought on this subject entered Torricelli's mind? 4. How many times is mercury or quicksilver heavier than water? 5. If water rise under pressure of the air 34 feet, how many inches will mercury rise? 6. Why does the mercury fall in the tube on the tops of mountains? 7. What important fact about the atmosphere has been made known to us through the barometer? 8. How does the mercury stand in calm dry weather, and how before storms? 9. In what respect does the barometer used at sea differ from that used on land? 10. What did the Chinese who conversed with Mr. Arnott think about the barometer? 11. Who raises up men such as Galileo, Newton, Watt, &c., to benefit mankind by their great discoveries? |