CHAPTER III. AEROLITES, OR METEORIC STONES.
These extraordinary substances are supposed to be connected in some way or other with meteors, as most of the stones which have fallen from the atmosphere have been preceded by luminous appearances. In some cases meteors have burst with a loud explosion, and then a shower of stones has fallen upon the earth. Sometimes these stones have continued luminous till they have touched the earth, but in other cases their brightness has disappeared the moment the meteor has burst. The meteoric stones, if examined immediately after their descent, are always hot, and they fall with such force that they generally bury themselves to a considerable depth. Their size differs from small stones like pebbles, to masses of several tons weight; they are usually round, and smell strongly of sulphur, and they are always covered with a black crust, which consists chiefly of oxide of iron. A great many instances of the fall of these stones have been recorded from the earliest ages to the present. In the Pagan times they were supposed to come from Heaven, and were regarded as objects of particular sanctity and, in fact, we have accounts of them in all countries and in almost all times, from the earliest records which have been handed down to us to the beginning of the present century. As nearly all the accounts are very similar to each other, a few of the most recent will suffice.
On the 18th of December, 1795, several persons, near the house of a Captain Topham in Yorkshire, heard a loud noise in the air, followed by a hissing sound, and soon after felt a shock as if a heavy body had fallen to the ground. One person, indeed, saw a large stone fall from the skies, at the distance of eight or nine yards from where he stood, and, on examining the stone, it was found to have buried itself twenty-one inches deep in the ground, and to weigh fifty-six pounds.
On the 12th of March, 1798, a similar noise was heard at Villefranche in the Department of the Rhône, and a large meteor was seen in the air, leaving behind it a long train of light, while it emitted, with almost incessant crackling, small vivid flames like little stars. Its fall was remarked by three labourers, who observed that a loud hissing proceeded from the spot where it fell. On examining the place, it was found to have made a hole about eighteen inches deep, and to consist of a large black metallic mass, bearing considerable resemblance in shape to a calf's head, and smelling very strong of gunpowder. It was cracked in several places, and when opened its interior was found hard, and of a granular texture, presenting different kinds of iron and other metals, mixed with different kinds of earth. The outside was partially vitrified and struck fire with steel.
The latest account that we have of the fall of any of these stones was a shower which fell near L'Aigle in Normandy, on the 26th of April, 1803. A cloud was seen passing between two and three o'clock in the afternoon, from which a noise issued like thunder; so loud that many persons ran out to see what was the matter, when the cloud burst, and a shower of stones descended, varying in weight from five to seventeen pounds. Several of them were darted down with such violence, that they were buried more than a foot deep in the ground, and they were all so hot that they burnt those who first attempted to take them up. In another account of this fall of stones in Normandy, the cloud is represented as a ball of fire, and some of the stones are said to have weighed less than half a pound. Both accounts agree in the stones being apparently compounded of different kinds of earths and metallic substances, and in all of them having a sulphureous smell. These Norman stones differed, however, from most of the other kinds which have been recorded, in being friable for some days after their descent.
CHAPTER IV. WINDS.
We understand by the word wind, a sensible current in the atmosphere. We have already observed that the air is an elastic fluid, capable of compression, and subject, in some degree, to the same laws as the denser fluids. If we remove a portion of water in a large reservoir, we see the surrounding water flow in to restore the equilibrium; and, in the same manner, if a portion of air is expanded by heat or condensed by cold, a counter current is the visible and natural result. Thus no winds can blow without a counter or opposite current, and no wind can arise without a previous derangement of the general equilibrium, which has probably arisen from one of the following causes. First, the ascent of air over certain tracts heated by the sun. Secondly, evaporation, causing an actual increase in the quantity of the atmosphere; and thirdly, rain, snow, &c., causing an actual decrease in the volume of air by the return of the aqueous vapour to the earth. Currents thus produced are either permanent and general, extending over a large portion of the globe; periodical, as in the Indian Ocean; or variable and uncertain, as winds in the temperate climates. The general permanent winds blow always nearly in the same direction, and are called trade-winds. "On the north of the equator their direction is from the north-east (varying at times a point or two of the compass each way); on the south of the equator, they proceed from the south-east. The origin of them is this:—the powerful heat of the torrid zone rarefies, or makes lighter, the air of that region: the air, in consequence of this rarefaction, rises, and, to supply its place, a colder atmosphere from each of the temperate zones moves towards the equator. But (as in the case of the polar currents in the ocean) these north and south winds pass from regions where the rotatory motion of the earth's surface is less, to those where it is greater. Unable at once to acquire this new velocity, they are left behind, and, instead of being north and south winds, as they would be if the earth's surface did not turn round, they become north-east and south-east winds. The space included between the second and fifth degrees of north latitude is the internal boundary of the two winds; and this space experiences calms, frequently interrupted, however, by violent storms." The trade-winds would blow regularly round the whole globe within the distance of thirty or forty degrees from the equator each way, if the space within those limits were all covered with water; but the uneven surface, and unequal temperature of the land divert and derange them. It is on this account that the trade-winds are constantly experienced only over the open ocean. The larger the expanse of ocean over which they range, the more steadily they blow; and thus in the Pacific they are commonly more steady than in the Atlantic Ocean. Both in the Atlantic and in the Pacific Ocean, the current of the trade-winds becomes broader and more directly east in its course as it advances from one side to the other of those extensive basins. On the west side of Africa, owing to the rarefaction which the air undergoes over that continent, the wind is mostly turned towards the shore; and along the coast of Chili and Peru, a south wind prevails. These are two instances of the interruption which the tradewinds experience in the neighbourhood of large masses of land; and in the Indian Ocean, the uniformity of the trade-winds is destroyed by the monsoons.
There are periodical winds, called monsoons, which blow half the year from one quarter, and the other half in an opposite direction. When they shift, variable winds and violent storms prevail for a time, which render it dangerous to put to sea.
The alternate land and sea breezes, which are common on coasts and islands situated between the tropics, are another kind of periodical winds. "During the day, the air over the land is strongly heated by the sun, and a cool breeze sets in from the sea; but, in the night, the atmosphere over the land is cooled, while the sea, and, consequently, the air over it, retains a temperature nearly even at all times; accordingly, after sunset, a land breeze blows off the shore. The sea breeze generally sets in about ten in the forenoon, and lasts till six in the evening. At seven, the land breeze begins, and continues till eight in the morning, when it dies away." These alternate breezes are, perhaps, felt more powerfully on the coast of Malabar than elsewhere, as their effect there extends to a distance of twenty leagues from the land; but they are also felt on the coast of the Mediterranean, and sometimes as far north as Norway.
A hurricane, properly speaking, means a violent tempest of wind, attended by thunder and lightning, and heavy rain or hail. Hurricanes appear to have an electric origin. At the moment the electric spark produces a combination of oxygen and hydrogen, a sudden fall of rain or hail is occasioned, and a vacuum is formed, into which the superincumbent air rushes in all directions, and occasions a hurricane. The velocity of the wind on these occasions exceeds that of a cannonball; corn, vines, sugar-canes, houses, and forests, are all swept away, particularly in the West Indies, where these fearful storms rage with the greatest fury. The hurricane of the temperate zone moves with a velocity of about sixty feet in a second; but those of the torrid zone move 150 or 200 feet in the same space of time. Hurricanes begin in various ways: sometimes a little black cloud rolls down the mountains, and then, unfolding itself, spreads over the whole horizon; and at other times the storm comes on in the shape of a fiery cloud, which suddenly appears in the midst of a calm and serene sky.
Among the remarkable hurricanes on record, may be mentioned one which occurred in Great Britain on the 26th of November, 1703. In London, upwards of two thousand stacks of chimneys were blown down, many houses were levelled with the ground, and many persons were killed. In the Thames 400 wherries were lost, and many barges sunk. At sea the destruction was still greater; twelve ships of war, with upwards of 1800 men on board, being totally lost, together with merchantmen.
In October, 1817, a tremendous hurricane took place in the West Indies, which was particularly severe in the island of St. Lucia, nearly all the buildings on the island being destroyed, and the ships in the port sunk, a great many lives being lost.
A violent hurricane took place in Thorndon Park, the seat of Lord Petre, near Brentwood, Essex, on the 12th of October, 1831. "The blast came on about eight o'clock in the evening and in less than four minutes the work of havoc was completed." The wind came from the south-west, and where it entered the park, it threw down a small portion of the paling. It then traversed the park in a varying sweep of about 150 yards in breadth; and the devastation it produced was terrific. In one place, it tore up by the roots several oaks sixty feet long, to which were left adhering masses of earth fourteen feet in length, and from three to four feet in thickness; and in another, a beautiful beech, which had been partly removed from the soil by the tearing up of the neighbouring trees, was left with its lofty top resting on an adjoining group at an angle of about thirty degrees. The following account of the appearance the park presented the day after the storm is given by an eye-witness:—"The stems of many trees are torn off within a few feet from the earth, some at a height of two or three feet, others at a greater height; and one elm has been severed at about twenty feet from the ground, fifteen feet of the stump having had half its body torn away. In one place, about 100 yards from this spot, the destruction has been tremendous. In a circle of nearly forty yards in diameter, whole trunks, huge limbs and branches, with immense masses of earth, lie on the ground in wild confusion, mingled in such a manner that it is impossible to count the number of trees destroyed. It appears as if a battery of heavy artillery had been directed against a great mass of timber, which had crowded that part of the park. In some instances the stems exhibit to the eye the appearance of having been cut off; in others, they are rent from top to bottom, or have had their giant limbs twisted off, as if they had been but so many twigs. Lofty oaks have been struck near their summits, and immense portions of their upper limbs and branches torn down, but not quite severed from their parent-stem, and they lie with their heads resting on the ground, forming a sort of tent or foliage upwards of thirty feet high. The hurricane spared neither the lofty nor the lowly, neither the mighty oak, nor the humble holly: the strong and the weak alike fell before the blast; and stripling trees, which one might have supposed would have escaped, shared the same fate with the monarchs of the park. Several oaks had at least a dozen immense branches torn off, while the majestic trunk has not lost a foot of its height, and in many instances the limbs and branches of standing trees are twisted and interlaced in a variety of fantastic shapes." The blast appears not to have taken a direct course, sweeping away all before it at the same height from the ground, but to have moved in an undulating direction, rising and falling over the trees like the billows of a mighty sea. "Near the house in a magnificent plantation of firs, several have been struck down or torn up, some of those destroyed having been from seventy to eighty feet high. In one place, a stately fir, nearly eleven feet in circumference, has been broken off at about the height of eighteen feet from the ground. To the stump are still attached on one side several large and graceful branches which have a very picturesque appearance." The severed part was blown to a distance of five or six yards from the foot of the tree, and was nearly covered by the trunks of three majestic elms, each ten feet in circumference, and sixty feet high. Near this place, what had been a clump of firs was reduced to a shapeless mass of trunks and branches. Altogether, not less than three hundred trees were torn up by the roots, or so much disfigured as to render it necessary to take up their remains; but most providentially no human beings were killed, the only living things that suffered being a pheasant and a crow. The hurricane also seems not to have taken the mansion in its range, and though the residence of Lord Petre's chaplain was in the park and embosomed in trees, it escaped uninjured, excepting that a few panes of glass were broken by the flying splinters of the trees, one of which entered the bedroom of the reverend gentleman. It is singular enough that the inhabitants of the mansion were not aware of the hurricane till it was all over, and that they fancied that the noise they heard was thunder. The hurricane was immediately succeeded by a tremendous fall of rain.