pposing they had fired their guns through hearing another go off;
but with a repeating rifle one has to fire before one can reload. The
fact was evident that Albert Cullen either had fired his Winchester up
by the mail-car, or else had not fired it at all. In either case he
had lied, and Lord Ralles and Captain Ackland had backed him up in it.

CHAPTER V

A TRIP TO THE GRAND CANON

I stood pondering, for no explanation that would fit the facts seemed
possible. I should have considered the young fellow's story only an
attempt to gain a little reputation for pluck, if in any way I could
have accounted for the appearance and disappearance of the robbers.
Yet to suppose--which seemed the only other horn to the dilemma--that
the son and guests of the vice-president of the Missouri Western, and
one of our own directors, would be concerned in train-robbery was to
believe something equally improbable. Indeed, I should have put the
whole thing down as a practical joke of Mr. Cullen's party, if it had
not been for the loss of the registered letters.

Even a practical joker would hardly care to go to the length of
cutting open government mail-pouches; for Uncle Sam doesn't approve of
such conduct.

Whatever the explanation, I had enough facts to prevent me from
wasting more time on that alkali plain. Getting the men and horses
back onto the cars, I jumped up on the tailboard and ordered the
runner to pull out for Flagstaff. It was a run of seven hours, getting
us in a little after eight, and in those hours I had done a lot of
thinking which had all come to one result--that Mr. Cullen's party was
concerned in the hold-up.

The two private cars were on a siding, but the Cullens had left for
the Grand Canon the moment they had arrived, and were about reaching
there by this time. I went to 218 and questioned the cook and waiter,
but they had either seen nothing or else had been primed, for not
a fact did I get from them. Going to my own car, I ordered a quick
supper, and while I was eating it I questioned my boy. He told me that
he had heard the shots, and had bolted the front door of my car, as I
had ordered when I went out; that as he turned to go to a safer place,
he had seen a man, revolver in hand, climb over the off-side gate of
Mr. Cullen's car, and for a moment he had supposed it a road agent,
till he saw that it was Albert Cullen.

"That was just after I had got off?" I asked.

"Yis, sah.

"Then it couldn'