Some of the machines were
making receivers for the stock, the largest piece of metal, and other
small parts like the trigger or the hammer, while still others were
preparing the barrels of the gun for drilling.
"It is not likely to occur to you," said his guide, "that it would not
do to let all those various parts cool off by chance. For example, in
winter they would cool more rapidly than in summer, and those near the
door more quickly than those in the inner part of the forging house.
That would make them of varying hardness. So, in order to make sure that
they shall be the same, all those pieces you have seen being made are
annealed."
"How is the annealing done?" asked Hamilton.
"That is simple enough," was the reply. "All that has to be done is to
heat them again all to the same degree of heat, then let the oven cool
at a certain rate. Here are the annealing ovens."
"This is certainly a hot place," said the boy, as he stepped into the
next building. "Whew! I wonder any one stays in here."
"No one does," his conductor answered. "We have this arranged so that
all the furnaces are filled in the morning, when they are cold, and
there are pyrometers to tell when the right heat is reached.
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