The iron mines of Sweden have long been celebrated; and the most remarkable are those of Dannemora, in which from twelve to fifteen hundred people are constantly employed. The opening of this mine is of great extent, and in it there are twelve pits in which mining operations are carried on. These pits are deep excavations like gravel pits, forming so many gulfs. "The descent into them is by means of baskets or buckets, each attached to a rope, which passes over a pulley; much as if there were a projection from the top of Salisbury steeple, from which, in a basket, one could be let down to the ground."
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DESCENT TO THE IRON MINES OF PERSBERG IN SWEDEN.
There are also extensive mines in Norway and the Ural mountains, as well as those in this country. Iron has been wrought in England since the time of the Romans, by whom iron works were established in the Forest of Dean in Gloucestershire. The iron works in this country are now very extensive, and it is estimated that they produce between five and six millions a year. The principal iron works of England are in the district round Birmingham and at Colebrook Dale. In Wales and Scotland are very extensive iron works, particularly those at Merthyr Tydvil in the former country, and at Carron in the latter.
TIN MINES.
The tin mines of Cornwall are supposed to have been worked upwards of 2,400 years, as they were known to the Phoenicians, who traded thither for tin. It is supposed, however, that the only one then worked was the stream tin, which is the most accessible. Tin, however, is now found not only in streams or veins, but in combination with copper and other metallic ores, or disseminated through the whole substance of granite and other rocks, which must be exposed to a strong degree of heat before the tin can be separated from them. Even when the tin is produced in veins, in some places tin and copper veins are united, and run parallel to each other, in a kind of double vein, of which the copper forms one side, and the tin the other.
There are tin mines in France, Portugal, and Germany, and in most cases the veins of tin, which are about six feet in thickness, are enclosed in granite. At Ehrenfriedersdorf, however, the mountain in which the tin lies, is of a kind of clay, and it contains a great number of parallel veins almost touching each other. In the Kaff mountain in Bohemia, there is a tin mine in which iron lies over the vein, and it is supposed that there is silver below it; but the most remarkable tin mine in Bohemia is that of Schlackenwald, in which the ore is contained in an enormous mass of granite, shaped like an inverted cone, and which is entirely surrounded by a rock of a different kind, while throughout the whole of the granite are disseminated innumerable grains of tin, which are so minute, that it requires ten thousand quintals of rock to yield thirty five quintals of tin.
COAL MINES.
The coal mines of Great Britain are of extraordinary extent and value, and, in fact, the prosperity of England depends in a great measure upon these extensive coal mines. It is supposed that the coal mines of Great Britain produce upwards of £8,000,000 sterling a year. Accidents in these coal mines are very frequent, partly from the explosions of inflammable gas, and partly from the presence of carbonic acid gas or choke damp as it is called. It appears from the returns that upwards of 20,000 persons lost their lives in coal mines in Great Britain in little more than twenty years. Numerous plans have been adopted to prevent these accidents, particularly what is called Sir Humphry Davy's safety lamp, but it does not appear to deserve that name, as many very serious accidents have happened in collieries where it has been in constant use.
SALT MINES.
The principal salt mines in England are in Cheshire, but there are brine springs, and it is supposed also salt mines, at Droitwich in Worcestershire, though the mines have not been worked. The first bed of fossil salt that was found in England was in 1670, when it was discovered about thirty-four yards below the surface in searching for coal in the neighbourhood of Northwich. About 100 years later a second bed of fossil salt was discovered near Lawton, about forty two yards below the surface; and others have since been discovered in various parts of the surrounding country. These salt beds are generally of an enormous thickness, and when one is pierced through, after passing through a thin layer of indurated clay, another bed of salt, of still greater thickness than the first, is generally found beneath.
Mines of rock salt occur in Hungary, the southern part of Germany, at Vic in France, and also at Wieliczka, near Cracow; the last being considered the most extensive salt mines in the world. The length of the great mine from east to west is 6,000 feet, and its breadth from north to south is 2,000 feet; its greatest depth is about 800 feet.
depth is 800. From the enormous size of this mine, it may be considered as a city underground, in which there are public roads and chapels. Numerous horses are employed to draw the blocks of salt to the mouth of the mine, and these horses, when once let down, remain during the whole of their lives. This, however, though told as wonderful, is by no means uncommon, as it occurs in many of the mines in Cornwall. There are also boys in the mines in both countries, who have either been born in the mines, or have been sent there so young that they have no recollection of ever having trodden on the surface of the earth. The most remarkable part of the salt mines of Poland is the chapel, which is hewn out of the salt rock, and has a large figure of our Saviour on the cross, formed also of salt. The number of men employed in this mine is said to be about 700.
FOSSILS.
Fossils are so called from a Latin word signifying that which may be dug out of the earth, which word, Professor Ansted informs us, was originally used in England as synonymous with mineral, but which has become now limited to its present meaning; or, in other words, synonymous with organic remains. Organic remains have been defined to be those "animal and vegetable substances which are contained in rocky strata, or found loose in the earth."
Fossils are of various kinds, but those which are most distinct and most numerous are of extinct animals, shells, and plants. Most of the shells are of kinds still in existence; but of the plants, many of the kinds are now rarely to be met with, and others are found in climates too cold for them now to exist in a living state. The most interesting fossils are, however, the remains of animals and zoophytes which have now become extinct, particularly those immense creatures of the lizard kind, which are totally unlike any animals now existing. One of these, the Ichthyosaurus, has a head like a lizard, armed with conical and pointed teeth; enormous eyes; and four limbs which can hardly be described, as they seem to have been something between paddles and feet. These animals, of which four species have been discovered, and of which the smallest is upwards of twenty feet long, have been only found imbedded in a kind of rock called oolite, and in the lias limestone.
They appear, from their construction, to have been carnivorous; and Professor Ansted has given us a striking description, in his Picturesque Sketches of Creation, of what he imagines to have been their habits.
"But let us see," he says, speaking of the early ages of the world, "what is going on in the deep abysses of the ocean, where a free space is given for the operations of that fiercely carnivorous marine reptile, the Ichthyosaurus. Prowling about at a great depth, where the reptilian structure of its lungs, and the bony apparatus of its ribs, would allow it to remain for a long time without coming to the air to breathe, we may fancy we see this strange animal, with its enormous eyes directed upwards, and glaring like globes of fire; its length is some thirty or forty feet, its head being six or eight feet long; and it has paddles and tail like a shark; its whole energies are fixed on what is going on above, where perhaps some gigantic fish is seen devouring its prey. Suddenly striking with its short but compact paddles, and obtaining a powerful impetus by flapping its large tail, the monster darts through the water at a rate which the eye can scarcely follow towards the surface. The vast jaws, lined with formidable rows of teeth, soon open wide to their full extent; the object of attack is approached—is overtaken. With a motion quicker than thought the jaws are snapped together, and the work is done. The monster becoming gorged, floats languidly near the surface, with a portion of the top of its head and its nostrils visible, like an island covered with black mud, above the water." Although this sketch is purely imaginative, it is very probable that it may be quite correct, as, from the remains of the reptile which have been discovered, it was evidently capable of all that has been described.
The Plesiosaurus is still more extraordinary in its formation; for it has a slender neck, as long as its body, rising from the lizard-like trunk, like the body of a serpent fixed on that of a lizard, and terminating in a very small head. Five species of this hydra-like monster have been discovered. The following is Professor Ansted's description of a Plesiosaurus.
"Imagine one of these monstrous animals, some sixteen or twenty feet long, with a small wedge-shaped crocodilian head, a long arched serpent-like neck, a short compact body, provided with four large and powerful paddles, almost developed into hands; an animal not covered with brilliant scales, but with a black slimy skin. Imagine for a moment this creature slowly emerging from the muddy banks, and half walking, half creeping along, making its way towards the nearest water. Arrived at the water, we can understand from its structure that it was likely to exhibit greater energy. Unlike the crocodile tribe, however, in all its proportions, it must have been dissimilar in habit. Perhaps, instead of concealing itself in mud or among rushes, it would swim at once boldly and directly to the attack. Its enormous neck, stretched out to its full length, and its tail acting as a rudder, the powerful and frequent strokes of its four large paddles would, at once, give it an impulse, sending it through the water at a very rapid rate. When within reach of its prey, we may almost fancy that we see it drawing back its long neck, as it depressed its body in the water, until the strength of the muscular apparatus with which this neck was provided, and the great additional impetus given by the rapid advance of the animal, would combine to produce a stroke from the pointed head which few living animals could resist. The fishes, including perhaps even the sharks, the larger cuttle fish, and innumerable inhabitants of the deep, would fall an easy prey to this monster."
The Pterodactyl is the most singular of all these inhabitants of a former world. In its external form, says Professor Ansted, it "probably resembled the bats or vampires; and some of the species attained the size of a cormorant, though others were not larger than a snipe. The resemblance, however, to the bat tribe, was limited to the form of the body, for the head was totally different, the snout being enormously elongated, and the eyes exceedingly large; while the organs of flight or wings were even more powerful in proportion, and the legs were probably capable of being used in water, and assisting the animal to swim. The neck also was long and like that of a bird." This extraordinary creature had sixty enormous teeth in its great jaws, and "the whole of the proportions of the head indicate a creature of great strength, capable either of darting down upon fishes, or preying upon the smaller land animals." The neck appears to have been very long; and an unusual provision is observable in it, assisting to give additional strength to the head; a set of bony tendons running along the vertebrae for this purpose. The length of the neck corresponds with what we see in birds, and indicates a perfect adaptation of the animal for rapid and long continued flight. In one specimen the head is thrown back so far, that the base of the skull almost touches the tail, without the bones appearing to be in an unnatural position." One of the peculiarities of this singular creature is, that it appears to have had a complete apparatus for walking as well as flying. "In order to effect this," Professor Ansted observes, "the bones of the fore extremity, so far as regards the shoulder and arm-bones, the wrist, and the hand, scarcely differ from the ordinary proportions of those bones in lizards, and correspond with the dimensions of the hinder extremity, so that up to this point there is no peculiar adaptation for flying. On examining the bones of the fingers, however, we find that the number of joints in that which corresponds to the little finger is increased to five, and each joint is enormously lengthened. To the whole of the little finger, thus produced till it has become longer than the body and neck together, a membranous wing was attached, which was also fastened to the rest of the arm, to the body, and to a portion of the hinder extremity. When, therefore, the arm was extended, the wing was not necessarily expanded, and only became so on the little finger being also stretched out so as to be at right angles to the arm; and the membrane was then nearly surrounded on four sides by bone. By this contrivance the necessity of employing the whole arm in the mechanism of flying as in the bird, or the whole hand as in the bat, was done away with, and the flying apparatus being confined to one finger, the arms and hands could be readily and conveniently made use of like the corresponding extremities of other animals." It appears, therefore, that this remarkable creature, which, in all points of bony structure from the teeth to the extremity of the nails, presents the characteristics of a reptile, was at the same time provided with the means of flying; and as its wings, when not in use, might be folded back like those of a bird, and its toes were free, that it could, at pleasure, stand firmly on the ground, walk about, climb rocks and cliffs, and possibly also swim in the ocean. Its usual position, when not in motion, or suspended from the branches of a tree, would probably be standing on its hind feet, with its neck set up and curved backwards, lest the weight of its enormous head should disturb its equilibrium.