Page:McClure's Magazine v9 n3 to v10 no2.djvu/458

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80

EDISON'S REVOLUTION IN IRON MINING.

pletely, none proving too much for Mr. Edison's indomitable will and rare concentration of mind and energy.

Yet what Mr. Edison really has done is a very simple matter; simple, that is, in its entirety. It may be explained in a few words. Mr. Edison is now doing on a gigantic scale just what he did at first with a hammer and a horse-shoe magnet. He is crushing rocks, and then dropping the resulting powder past powerful electro-magnets. The sand is not affected by the magnetism and passes straight on; the iron ore is attracted to one side and falls in a heap of its own. This is the whole principle. But in the actual working out it becomes one of the most tremendous processes in the world. It is, after all, no small matter to crush the very vitals out of a big mountain and then extract all of the ore from millions of tons of sand. In the middle distance between the first simple experiment and the practical working plant is a vast region full of economic detail, commercial reckoning, and mechanical devising, dependent on the difference between breaking up small rocks with a hammer and breaking up whole mountains with heavy machinery. What Mr. Edison has done has been to subdue to his service three great natural forces—momentum, magnetism, and gravity. The big rocks are not, strictly speaking, crushed by the direct power of an engine or dynamo; momentum alone turns them into dust. No mechanism assists in the separation of the ore from the sand; magnetism does it all. Except for the elevators which raise the ore to the cupolas of the buildings, there is in many of them no machinery; gravity does all the work. In fact the whole plant is a wonderful example of automatic action. Every part is connected with the other parts, and the aggregate is as compact and as self-sustaining as a modern rotary printing-press, and is even less dependent on human agency for assistance.

From the time the ore is blasted with its native rock out of the mountain-side until it is loaded in the form of commercially pure iron briquettes on the cars, it is not touched by human hands. The never-ending and never-resting stream of material constantly circulates through the various buildings, crushed by the stored momentum of gigantic rolls; hoisted skyward by steam; pulled earthward by gravity; deflected by magnetism; dried, sifted, weighed, gauged, conveyed; changed from rock into dust, and from dust into comprehensive lumps, mixed with a due proportion of adhesive material; churned, baked, counted, and sent flying to the furnaces by fast freight; and not once in its course is it arrested or jogged onward by human agency. The noise of the crushing, the grind of the machinery, the dust and the onrushing stream of this "most precious metal" and its by-product, separate the 145 attendants as with the breadth of continents. Yet these men, merely watchers to see that all goes well, are within signal distance of one another in spite of the noise, the dust, and the grind; and the touch of a button quells the monstrous disturbance in the smallest fraction of time.

AN ACCIDENT TO THE STEAM SHOVEL.

The steam shovel seems to be as voracious as a great animal. Sometimes it attacks rocks which are too big even for its own great maw. In its effort to overcome a great rock it lost its balance and tipped over.

The complete subjection and masterful control of great natural forces is one of the most impressive aspects of the whole enterprise. It is one thing to set the ball in motion; it is quite another to control its velocity or direct its course. The crushing capacity of all the stamp-mills in California is about 5,000 tons a day. The crushing capacity of Edison's giant and lesser rolls is twenty per cent, greater than that of all these mills combined; enough to level in an ordinary life-time the proudest of mountain peaks. The