uppermost. The plates are held in position by hydraulic rams, which
also prevent bulging. Molten steel of medium softness is then poured
into the space between the plates, by means of a distributing trough
having holes in the bottom, and after this has solidified, the whole
plate is placed under the hydraulic press and reduced about twenty per
cent. in thickness. The plate is then passed through the rolls, bent,
planed, fitted, tempered, and annealed to reduce internal strains.

[Illustration: Fig. 8.]

In heating the compound plates for rolling, the plate is placed in the
furnace with the steel face down, so that the iron part gets well
heated and the steel does not become too hot. Great care must be taken
not to overheat the plate, and in working, many passes are given the
plate with small closings of the rolls. The steel part of a compound
plate is usually about one third of the full thickness of the plate.

Forged steel armor, tempered in oil, is fabricated at Le Creusot,
France, by Schneider & Co., using open-hearth steel, and forging under
the 100 ton hammer. The ingots are cast, with twenty-five per cent.
sinking head and are cubical in form. The porter bar is attached to a
lug on one side of the ingot. By means of a crane with a curved jib
which gives springiness under the hammer, the ingot is thrust into the
heating furnace. On arriving at a good forging heat it is swung around
to the 100 ton hammer, under which it is worked down to the required
shape. A seventy-five ton ingot requires about eight reheatings before
being reduced to shape. Having been reduced to shape, the plate is
carefully annealed, then raised to a high tempering heat, and the face
tempered in oil. It is reannealed to take out the internal strains,
care being taken not to reduce the face hardness more than necessary.