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Stages in the Making of a Big Gun
��At the top, a glimpse of one of the big gun-heat- ing furnaces. The huge steel ingots or blocks are heated before they are worked or forged to a smaller size, just as a blacksmith forges down a tool. Big cranes handle these heavy steel pieces by means of some of the mechanism shown and insert them into a furnace or draw them out with the utmost ease. These heating or soaking fur- naces, as they are called, are fired by gas, oil or .oal. Steel, to be worked or kneaded like bread, must be at a white heat
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