e charcoal was intensely hot, but not hot enough to catch fire.
The pieces of finished steel were buried in this charcoal, and every
few minutes the men in charge would draw them out, wipe them over with a
bunch of oiled waste, and thrust them back into the fire. It was about
the dirtiest, blackest, grimiest work the boy had ever seen.

"That is the old way," Hamilton was told, "and although it is handwork
instead of machine work it is not a bit better in its results than the
new way. The modern system, besides, is much simpler and cleaner."

In the next building was a row of charcoal ovens, revolving in such a
way that the parts to be blued were alternately covered and released
from the superheated charcoal, the effect of the greasing also being
done at every automatic revolution Each furnace door bore an asbestos
clock.

"What are those clocks for?" asked Hamilton. "The same as those others,
I suppose, so that the man in charge can put in a number of certain
parts of a gun and leave them in for a regular length of time at a
certain heat, and pull them out all done?"

"Just that," was the reply. "The only gain in the old style is that each
part being handled separately, if there is ever so little difference in
the metal, the bluer can give it a shorter or a longer time, whereas
the machine treats all alike."

"Then when the gun is assembled, all the work is done?" queried
Hamilton, who was becoming a little tired from his long tramp through
the works and among the furnace-heated shops.

"No," said the other. "That wouldn't do at all. A gun has not only got
to shoot, but it has got to shoot straight."

"But how in the world," said Hamilton, "can you tell whether a gun will
shoot straight or not?"

"One of the most important ways," said his informant, "is to let an
expert look through the barrel. One of our best men, for example, has
done nothing else all his life; his father before him was a
barrel-sighter and his son has just entered the works. He does it this
way--here, you try," and he handed a barrel to Hamilton. "Rest the
barrel in this crotch," he continued, "and look at the window. You see
there is a piece of ground glass with a thin black line running across
it. Point the barrel so that it is aimed just below that line, and if
you get it right, you will see a reflection of that line running
lengthways up the barrel."

[Illustration: MAKING GUN-SIGHTS TRUE. Marksmen firing new-made rifles
and adjusting