finger nail, "is the Southern Soudan. Here's the Bambara country to
the north of Uasule. Now right at this point, in the Moon Mountain
range,"--he pointed to a red-marked trail zigzagging across the map
to the range and terminating in a red star--"right at that thar
point, old Muley-Hassan, the Arab, has hidden our ivory cache. You
see the latitude and longitude is marked and furthermore--and here's
the most remarkable part of it--you will know the spot when you see
it by the fact that the mountains above the cache present an exact
facsimile of an upturned human face. In a direct line drawn from
the nose of this face, where you see the red star, lies the ivory."

The boys were deeply interested. Unpleasant as was the impression
old Barr had made on them, yet what he was disclosing was
impressive; but as yet they did not show that they were anything
more than casually struck by it.

"Well, Mr. Barr?" said Frank, as the old matt paused impressively.

"Well--" said Mr. Barr, "the scoundrel stole it and it's up to you
to get it out of there, if you will undertake it."

"How does it depend on us?" asked Frank.

"In just this way. Muley-Hassan has his eye on us---we can do
nothing toward locating the ivory. You can pitch a camp there and
scout about for it in your aeroplane or dirigible or whatever you
call it."

"But even if we do find the Arab's hiding-place, what good does that
do?" objected Frank.