Page:Popular Science Monthly Volume 91.djvu/62

 Cooling the Steel Under Pressure

���Steel, when it cools, contracts to such an extent that a hollow space is always left in the center of the upper part of a large body of metal. The extent of this cavity, or " pipe," is greatly reduced under pressure so that this natural contraction is taken up or prevented and a solid block obtained. The picture represents what is known as a fit-id compression plant or press in which hot steel can be allowed to cool under a constantly increased pressure

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