The wonders of the world

by John Loraine Abbott

Iron, although one of the imperfect metals, is susceptible of a very high polish, and more capable than any other metal of having its hardness increased or diminished by certain chemical processes. It is often manufactured in such a way as to be one hundred and fifty times, and, as will now be seen, in some cases, to be even above six hundred and thirty times more valuable than gold. On weighing several common watch-pendulum springs, such as are sold for ordinary work by the London artists, at half a crown, ten of them were found to weigh but one single grain. Hence one pound avoirdupois, equal to seven thousand grains, contains ten times that number of these springs, which amount, at half a crown each, to eight thousand, seven hundred and fifty pounds sterling. Reckoning the troy ounce of gold at four pounds sterling, and the pound equal to fifty-seven hundred and sixty grains, at forty-eight pounds sterling, the value of an avoirdupois pound of gold is over fifty-eight pounds sterling. The above amount of the value of the watch-springs weighing an avoirdupois pound, being divided by that sum, will give a ratio of somewhat more than one hundred and fifty to one. But the pendulum-springs of the best kind of watches sell at half a guinea each; and at this price the above-mentioned value is increased in the ratio of four and one-fifth to one; which gives an amount of thirty-six thousand, seven hundred and fifty pounds sterling. This sum being divided by the value of the avoirdupois pound of gold, gives a quotient of more than six hundred and thirty to one.

It is one of the valuable properties of iron, after it is reduced into the state of steel, that, although it is sufficiently soft when hot, or when gradually cooled, to be formed without difficulty into various tools and utensils, still it may be afterward rendered more or less hard, even to an extreme degree, by simply plunging it, when red-hot, into cold water. This is called tempering, the hardness produced being greater in proportion as the steel is hotter and the water cooler. Hence arises the superiority of this metal for making mechanics’ instruments or tools, by which all other metals, and even itself, are filed, drilled and cut. The various degrees of hardness given to iron, depend on the quantity of ignition it possesses at the moment of being tempered, which is manifested by the succession of color exhibited on the surface of the metal, in the progress of its receiving the increasing heat. These are, the yellowish white, yellow, gold-color, purple, violet, and deep blue; after the exhibition of which the complete ignition takes place. These colors proceed from a kind of scorification on the surface of the heated metal.

The largest iron-works in England are carried on in Colebrookdale[Colebrookdale], in Shropshire. This spot, which is situated between two towering and variegated hills, covered with wood, possesses peculiar advantages, the ore being obtained from the adjacent hills, the coals from the vale, and abundance of limestone from the quarries in the vicinity. The romantic scenery which nature here exhibits, and the works which are carried on, seem to realize the ancient fable of the Cyclops. The noise of the forges, mills, &c., with all their vast machinery, the flames bursting from the furnaces, with the burning coal, and the smoke of the lime-kilns, are altogether horribly sublime. To complete the peculiarities of the spot, a bridge, entirely constructed of iron, is here thrown over the Severn. In one place it has parted, and a chasm is formed; but such is its firm basis, that the fissure has neither injured its strength nor utility.

The great superiority of Swedish iron over that of all other countries, for the manufacture of steel, is well known, and is ascribed to the great purity of the ore from which the iron is smelted. The British steel-makers have found it difficult to employ British iron in their processes, it being too brittle to bear cementation; but attempts have been made at Sheffield, with some success. Wootz, a species of steel from India, has been successfully used for nicer kinds of cutlery. One of the most remarkable of the Swedish mines, if the name can with propriety be applied to it, is Tabern, a mountain of a considerable size, composed entirely of pure iron ore, and occurring in a large tract of sand, over which it seems to have been deposited. This mountain has been wrought for nearly three centuries, notwithstanding which its size is scarcely diminished.

But the richest iron mine of Sweden is that of Danmora, in the province of Upland. It is in depth eighty fathoms; occupies a considerable extent of territory; and its ore is conveyed to the surface of the earth, through several pits or openings made for that purpose, by means of casks fixed to large cables, which are put in motion by horses. The workmen standing on the edges of these casks, and having their arms clasped round the cable, descend and ascend with the utmost composure. The water is drawn from the bottom by a wheel sixty-six feet in diameter, and is afterward conveyed along an aqueduct nearly a mile and a half in length. At certain distances from Danmora, are several furnaces, with large and populous villages exclusively inhabited by the miners.

In Wraxall’s tour through the north of Europe, the mine of Danmora is described as yielding the finest iron ore in Europe, its produce being exported to every country, and constituting one of the most important sources of national wealth and royal revenue. The ore is not dug, as is usual in other mines, but is torn up by the force of gunpowder, an operation which is performed every day at noon, and is one of the most awful and tremendous that can possibly be conceived. “We arrived,” observes the tourist, “at the mouth of the great mine, which is nearly half an English mile in circumference, in time to be present at it. Soon after twelve the first explosion took place, and could not be so aptly compared to anything as to subterraneous thunder, or rather volleys of artillery discharged under ground. The stones were thrown up, by the violence of the gunpowder, to a vast hight above the surface of the ground, and the concussion was so great as to shake the surrounding earth or rock on every side.

“As soon as the explosion had ceased, I determined to descend into the mine, to effect which I had to seat myself in a large, deep bucket, capable of containing three persons, and fastened by chains to a rope. When I found myself thus suspended between heaven and earth by a rope, and looked down into the dark and deep abyss beneath me, to which I could see no termination, I shuddered with apprehension, and half repented my curiosity. This was, however, only a momentary sensation, and before I had descended a hundred feet, I looked round on the scene with very tolerable composure. It was nearly nine minutes before I reached the bottom; and when I set my foot on the earth, the view of the mine was awful and sublime in the highest degree. Whether, as I surveyed it, terror or pleasure formed the predominant feeling, is hard to say. The light of the day was very faintly admitted into these subterraneous caverns: in many places it was absolutely lost, and flambeaux were kindled in its stead. Beams of wood were laid across some parts, from one side of the rock to the other; and on these the miners sat, employed in boring holes for the admission of gunpowder, with the most perfect unconcern, although the least dizziness, or even a failure in preserving their equilibrium, must have made them lose their seat, and have dashed them against the rugged surface of the rock beneath. The fragments torn up by the explosion, previously to my descent, lay in vast heaps on all sides, and the whole scene was calculated to inspire a gloomy admiration.

“I remained three-quarters of an hour in these frightful and gloomy caverns, which find employment for not less than thirteen hundred workmen, and traversed every part of them which was accessible, conducted by my guides. The weather above was very warm, but here the ice covered the whole surface of the ground, and I found myself surrounded with the colds of the most rigorous winter, amid darkness and caves of iron. In one of these, which ran a considerable way beneath the rock, were eight wretched beings warming themselves round a charcoal fire, and eating the little scanty subsistence arising from their miserable occupation. They rose with surprise at seeing so unexpected a guest among them, and I was not a little pleased to dry my feet, which were wet with treading on the melted ice, at their fire.

“Having gratified my curiosity with a view of these subterraneous apartments, I made the signal for being drawn up, and felt so little terror while reascending, compared with that of being let down, that I am convinced, after five or six repetitions, I should have been perfectly indifferent to the undertaking. So strong is the effect of custom on the human mind, and so contemptible does danger or horror become when familiarized by repeated trials!”

Throughout the whole extent of Sweden, the iron mines at present wrought, employ thousands of persons, and yield annually upward of one hundred thousand tuns of metal. There are said to be between five and six hundred mines in the entire country, nearly half of which are situated in the central provinces: this, however, includes mines of all descriptions, though by far the most are of iron. The products of all these mines would be vastly greater than they are, were it not for the multiplied and unreasonable restrictions of the government.