hs previously Alex and Jack had arranged to take their two
weeks' vacation at the same time, and to spend one week at Haddowville,
Jack's home, and the other at Bixton.

The long looked-for Monday had at length arrived, early that morning Jack
had joined Alex at Exeter, and the two boys, aboard the Eastern Mail,
were now well on their way to Haddowville.

For some minutes Alex's part in the animated conversation of the two
chums had waned. Presently, plucking Jack's sleeve, he quietly directed
his companion's attention to the double seat across the aisle of the car.

"Jack, watch that soldier's fingers," he said in a low voice. "What's the
matter with him?"

The soldier in question, in the uniform of an infantry regular, sat
facing them, beside a stout elderly gentleman. Opposite the first soldier
was a second, in a similar uniform; and sharing the seat with the latter,
and facing the old gentleman, was a decidedly pretty young girl.

It was the first soldier's left hand, however, which attracted the boys'
particular attention. Resting in his lap, and partly concealed by a
newspaper, the hand was so doubled that the thumb stood upright. And this
latter member was bobbing and wagging up and down, now slowly, now
quickly, in most curious fashion.

"Perhaps it's St. Vitus' dance," ventured Jack.

"But that affects the whole body, or at least the whole limb, doesn't
it?"

Jack, who sat next the window, leaned slightly forward. "The other
soldier is watching him," he said. "Maybe the fellow with the wiggling
thumb is out of his mind, and this one is taking him somewhere. He is
watching his hand."

Silently the boys continued to regard the curious proceeding.

Suddenly the thumb became quiet, there was the rattle of a paper in the
hands of the second soldier, and in turn his thumb became affected with
the wagging. In a moment the boys understood.

The two soldiers were army signallers, and were carrying on a silent
conversation, using their thumbs as they would a flag.

Jack and Alex looked at one another and laughed softly. "We're bright,
eh?" Alex remarked.

"Let us watch when the other starts again--we can't see this chap's hand
well enough--and see if we can't read it," suggested Jack. "That one-flag
signal system is based on the telegraph dot and dash code, you know. And
it's not likely they are speaking of anything private--only amusing
themselves."

The paper opposite again covered the first soldier's