Every-day Science: Volume 6. The Conquest of Nature

by Henry Smith Williams; Edward Huntington Williams

Quite recently lake-navigators have learned, what rivermen have long known, that cheap transportation may be effected on a large scale by barges and towing. Before the outbreak of the Civil War forty years ago, the Mississippi river swarmed with great cargo-carrying steamers, employing armies of men and consuming enormous quantities of fuel. But after the war the experiment was tried of hauling the cargoes on barges towed by tug boats, and this proved to be so much cheaper that the fleet of great river boats soon disappeared. In somewhat the same way the barge has come into use of late years in the ore-traffic, and the great ore-steamers now tow behind them one or two barges equal in carrying capacity to themselves. In this way three ships' cargoes of ore are transported a thousand miles by a score of men, a dozen on the steamer and three or four on each of the barges. The barges themselves are rigged as ships, and if necessary can shift for themselves by means of sails attached to their stubby masts. But these are used only on special and unusual occasions, as in case of accidental parting of the hawsers during a storm.

The problem of loading the ships at the ore wharves is a simple one as compared with the equally important one of transferring the ore from the hold to trains of cars in waiting at the eastern end of the water route. For four handlings of the ore are necessary before it is finally deposited in the furnaces in the east. The first of these is from the mine to cars; the second from the cars to the boats; the third from the boats to cars; and the fourth from the cars to the blast furnaces.

For many years about the only hand work done in any of these processes was that of transferring from the boats to the ore-trains, and even here "automatic unloaders" are now rapidly supplanting the tedious hand method. By the older methods a travelling crane, or swinging derrick, dropped a bucket into the hold of the ore-vessel, where workmen shovelled it full of the red ore. It was then lifted out by machinery and the contents dumped into cars in much the same manner as that of the steam shovel in the mines. Recently, however, a machine has been perfected which scoops up the ore from the ship's hold and transfers it to the cars without the aid of shovellers. The only human aid given this gigantic machine is to guide it by means of controlling levers—to furnish brains for it, in short—the "muscle" being furnished by steam power. The great arm of this automatic unloader, resembling the sweep of the old-fashioned well in principle, moves up and down, burying the jaws of the shovel into the ore in the hold, and pulling them out again filled with ore, with monotonous regularity, quickly emptying the vessel under the guidance of half a dozen men, and performing the labor of hundreds.

Thus the last field of activity for the laborer and his shovel, in the iron-ore industry, has been usurped by mechanical devices. From the time the ore is taken from the mine until it appears as molten metal from the furnaces, it is not touched except by mechanisms driven by steam, compressed air, or electricity. And yet, so rapid is the growth of the iron and steel industry that there is almost always a demand for more workmen.

For this reason, and perhaps because of the "American spirit" among workmen, innovations in the way of labor-saving machinery are not resisted among the mine laborers. The American workman seldom resists or attacks machinery on the ground that it "throws him out of a job," as does his English cousin. It would be unjust to attribute this attitude to superior acumen on the part of the American workman, and it is probably a difference in conditions and surroundings that accounts for the diametrically opposite views held by laborers on the two sides of the Atlantic. But after all, results must speak for themselves, and the advantage all lies in favor of the progressive attitude of the western laborer, if we may judge by the relative social status and financial standing of European and American workmen.

THE CONVERSION OF IRON ORE INTO IRON AND STEEL

Since steel is a compound substance composed essentially of two elementary substances in varying proportions, it appears that the name "steel," like wood, refers to a class of which there are several varieties. This, of course, is the case, but for the moment we may consider steel as a single substance composed chiefly of iron and containing a certain percentage of carbon. In this respect it resembles cast iron, steel having a smaller amount of carbon. Wrought iron, on the other hand, contains no carbon at all, or at least only a trace of it. But whatever the ultimate destiny of iron ore—whether it is to become aristocratic manganese steel, or plebeian cast iron—it must first pass through certain processes before being "converted."

To extract the pure iron from the iron ore it is necessary to heat the ore in a furnace containing a certain quantity of coal, coke, or charcoal, and limestone. The furnaces used in this process are known as blast-furnaces, and in these about one ton of iron is extracted for every two tons of Lake Superior ore, one and a quarter tons of coke, and half a ton of limestone used. These quantities are by no means constant, of course, but they may be taken as representing roughly the relative amounts of material that must be fed into the furnaces.

Like everything else in the world of iron and steel, these blast-furnaces have undergone revolutionary improvements during the past quarter of a century. From being most dangerous and destructive structures causing frightful loss of life and producing only about one ton of iron a day for every man working about them, as formerly, they have now become relatively harmless monsters, capable of turning out six times that quantity of ore for each man employed.

The older blast-furnace was a huge, chimney-like structure, perhaps a hundred feet high, into which the ore, coal, and limestone were poured. Most of the work about these furnaces was done by manual labor, or at least manual labor was an active assistant to the machinery used in manipulating the furnaces. The top of the furnace was closed in by a great movable lid, or "bell," and the material for charging it was hauled up the sides by elevators and dumped in at the top. About the top of the furnace was constructed a staging upon which the workmen stood, an elevator shaft connecting the staging with the ground. The ore and other materials were brought to the foot of the shaft on cars from which it was shovelled into peculiarly designed wheelbarrows, trundled to the elevator, and hauled to the top.