An Autobiography [136]
was one of peculiar interest. I may in the first place say that the immense collection of iron ore at that point has been the result of the upheaval of a vast volume of molten igneous ore, which has been injected into the rock, or deposited in masses under the crust of the earth. In some cases the quarried ore yields from 50 to 70, and even as much as 90 per cent of iron. The Dannemora Mine is a vast quarry open to the sky. When you come near it the place looks like a vast deep pit, with an unfathomable bottom. Ghostlike, weird-looking pinnacles of rocks stand out from its profound depths; but beyond these you see nothing but wreaths of smoke curling up from below. The tortuous chasm in the earth, caused by the quarries beneath, is about half a mile long, and about a thousand feet wide.
[Image] Dannemora iron mine. After a drawing by James Nasmyth.
The first process of the workmen in the quarries below is devoted to breaking into small fragments the great masses of ore scattered about by the previous night's explosions. These are sent to the surface in great tubs attached to wire ropes, which are drawn up by gins worked by horses. Other miners are engaged in boring blast holes in the ore, which displays itself in great wide veins in the granite sides of the vast chasm. These blast holes are charged with gunpowder, each with a match attached. At the end of the day the greater number of the miners are drawn up in the cages or tubs, while a few are left below to light the slow-burning matches attached to about a hundred charged bore holes. The rest of the miners are drawn up, and then begins the tremendous bombardment. I watched the progress of it from a stage projecting over the wild-looking yawning gulph. It was grand to hear the succession of explosions that filled the bottom of the mine far beneath me. Then the volumes of smoke, through the surface of which masses of rock were sometimes sent whirling up into the clear blue sky, and fell back again into the pit below. Such an infernal cannonade I have never witnessed. In some respects it reminded me of the crater of Vesuvius, from which such dense clouds of steam and smoke and fire are thrown up. In the course of the night, the suffocating smoke and sulphureous gases has time to pass away, and next morning the workmen were ready to begin their operations as before.
The ore extracted from this great mine is smelted in blast furnaces with wood charcoal, and forged into bars. The charcoal is, of course, entirely free from sulphur. When sent to Sheffield the iron is placed in fire-brick troughs closely surrounded by powdered charcoal. After a few days' exposure to red heat, the iron is converted into splendid steel, which has given such a reputation to that great manufacturing town. It is also the steel from which the firm of Stubbs and Company, of Warrington (to which I have already referred), produce their famous P.S. files.
After the explosions had ceased at the mine, I went with one of the managers to see the great Bar forge. It was a picturesque sight to see the forgemen at work with the tilt hammers under the glowing light of the furnaces. I inspected the machinery and forge works throughout, and had thus the opportunity of seeing the whole proceeding, from the blasting and quarrying of the ore in the mine, the forging and rolling of the worked iron into their proper lengths, down to the final stamp or "mark" driven in by the blow of the tilt hammer at the end of each bar. Having now thoroughly examined everything connected with this celebrated iron mine, I prepared to set out for Stockholm in the same way as I had come. To prepare the landlord for my setting out, I again resorted to my pencil. I made a drawing of the little gig and pony, with the sun rising, and the hour at which I wished to start. He understood it in a moment, and next morning the trap was at the door at the specified time.
Before I left Stockholm I made a careful and elaborate panoramic sketch of the city, as a companion to the one I had made of Genoa from the
[Image] Dannemora iron mine. After a drawing by James Nasmyth.
The first process of the workmen in the quarries below is devoted to breaking into small fragments the great masses of ore scattered about by the previous night's explosions. These are sent to the surface in great tubs attached to wire ropes, which are drawn up by gins worked by horses. Other miners are engaged in boring blast holes in the ore, which displays itself in great wide veins in the granite sides of the vast chasm. These blast holes are charged with gunpowder, each with a match attached. At the end of the day the greater number of the miners are drawn up in the cages or tubs, while a few are left below to light the slow-burning matches attached to about a hundred charged bore holes. The rest of the miners are drawn up, and then begins the tremendous bombardment. I watched the progress of it from a stage projecting over the wild-looking yawning gulph. It was grand to hear the succession of explosions that filled the bottom of the mine far beneath me. Then the volumes of smoke, through the surface of which masses of rock were sometimes sent whirling up into the clear blue sky, and fell back again into the pit below. Such an infernal cannonade I have never witnessed. In some respects it reminded me of the crater of Vesuvius, from which such dense clouds of steam and smoke and fire are thrown up. In the course of the night, the suffocating smoke and sulphureous gases has time to pass away, and next morning the workmen were ready to begin their operations as before.
The ore extracted from this great mine is smelted in blast furnaces with wood charcoal, and forged into bars. The charcoal is, of course, entirely free from sulphur. When sent to Sheffield the iron is placed in fire-brick troughs closely surrounded by powdered charcoal. After a few days' exposure to red heat, the iron is converted into splendid steel, which has given such a reputation to that great manufacturing town. It is also the steel from which the firm of Stubbs and Company, of Warrington (to which I have already referred), produce their famous P.S. files.
After the explosions had ceased at the mine, I went with one of the managers to see the great Bar forge. It was a picturesque sight to see the forgemen at work with the tilt hammers under the glowing light of the furnaces. I inspected the machinery and forge works throughout, and had thus the opportunity of seeing the whole proceeding, from the blasting and quarrying of the ore in the mine, the forging and rolling of the worked iron into their proper lengths, down to the final stamp or "mark" driven in by the blow of the tilt hammer at the end of each bar. Having now thoroughly examined everything connected with this celebrated iron mine, I prepared to set out for Stockholm in the same way as I had come. To prepare the landlord for my setting out, I again resorted to my pencil. I made a drawing of the little gig and pony, with the sun rising, and the hour at which I wished to start. He understood it in a moment, and next morning the trap was at the door at the specified time.
Before I left Stockholm I made a careful and elaborate panoramic sketch of the city, as a companion to the one I had made of Genoa from the