been accustomed to in his old Kentucky home, before his
father died, that they often puzzled him; but Bob was a persistent boy,
and would never rest content until Frank could teach him no more.

Neither of them suspected what was going on outside, while they busied
themselves in purchasing the supplies needed for the little campaign in
the neighborhood of the mysterious mountain. And yet all was not as
quiet as it might be.

The saddle boys had hardly been inside the general store ten minutes
before a slinking figure might have been observed drawing nearer and
nearer to the horses ranged along the bar. There were several besides
the animals of our two young friends; but, somehow, the handsome black
seemed to attract the entire attention of this shadowy form.

Twice he stopped, and assumed an attitude that would indicate his utter
indifference to such commonplace things as horses. Then, finding that
it must have been a false alarm, he would edge closer.

Finally he was beside the black horse, uttering low words such as
cowboys make use of to soothe a restive steed when they mean to throw a
saddle across his back, and cinch the girth.

Two men came out from the store, and drew near. The slim figure,
finding it out of the question to flit hurriedly away, without
attracting attention, which was just the thing he wished to avoid,
commenced stroking the sleek side of the big black Kentucky
thoroughbred, as though he might be a cowboy connected with the far
famed Circle ranch of Frank's father.

Casting just one casual glance toward him, the men threw themselves
into their saddles with the rapidity and grace of true plainsmen, and
went galloping off.

Two minutes later the shadowy figure of the man flitted away from the
line of horses that remained. If his purpose had been to steal the
black he must have changed his mind, for there was no break in the
chain of horses that stood there, impatiently scraping the ground with
their forefeet.

A little later out came Frank and Bob, each bearing a compact bundle
which they quickly fastened back of their saddles.

Bob was the first to mount, and this action was hurried because he
hardly knew what to make of the restless actions of Domino. The animal
seemed to be dancing up and down as though he had stirred up a hornet's
nest, and the little insects were charging his exposed legs.

No sooner was Bob in the saddle than the horse gave a shrill neigh, and
dashed off like