powder. I think the men feel more
comfortable when they use that milder name. There was "powder" enough on
this train to wreck a city, but nobody seemed to mind. The horses
switched their tails. The men laughed and loitered. They might have been
laying bricks, for any interest they showed.

I asked one of them if it is considered safe to haul car-loads of
dynamite about the country. He said that some people consider it safe,
and some do not; some railroads will carry dynamite, while others refuse
it.

"Suppose a man were to shoot a rifle-ball into one of these cars," I
asked, "do you think it would explode?"

This led to an argument. One of the group was positive it _would_
explode. Concussion, he declared, is the thing that sets off dynamite.
Another knew of experiments at the works where they had fired
rifle-balls into quantities of dynamite, and found that sometimes it
exploded and sometimes it didn't.

Then a third man spoke up with an air of authority. "You've got to have
a red spark," said he, "to set off dynamite. I've handled it long enough
to know. Here's an experiment that's been tried: They took an old
flat-car and loaded it with rocks; then they fastened a box of dynamite
to the bumper, and let the car run down a steep grade, bang! into
another car anchored at the bottom. And they found that the dynamite
never exploded unless the bumpers were faced with iron. It didn't matter
how much concussion they got with wooden bumpers, the dynamite was like
that much putty; but as soon as a red spark jumped into it out of the
iron, why, off she'd go."

Then he instanced various cases where powder-cars had gone through
railroad wrecks without exploding, although boxes of dynamite had been
smashed open and scattered about.

"How about that car of ours the other day up in central New York?" said
the first man. "Everything blown to pieces, and six lads killed."

He smiled grimly, but the other persisted: "That collision only proves
what I say. There was a red-hot locomotive plowing through a car of
dynamite, and of course she went up. But it wasn't the concussion did
it; it was the sparks."

"You say that it takes a red spark," I observed, "to set off dynamite.
Do you mean that a white spark wouldn't do it?"

"That's what I mean," said he. "It seems queer, but it's a fact. Put a
white-hot poker into a box of dynamite, and it will only burn; but let
the poker cool down until it's only red-hot and the dynamite wil