"Now, I heard about you boys and your air-ship, and I heard, too, that you was planning a little trip to Africa and thought you might like to combine business and pleasure."
He drew from his pocket a much-thumbed, crudely drawn map and spread it out on the table. How he obtained it, the boys never learned exactly, but they heard later that a treacherous attendant of the ivory dealer had sold it to him for a good round sum.
"This country down here," he said, indicating it with a black rimmed 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.
"We can arrange with the French government to send soldiers up into the country and get the stuff out, if necessary," readily replied the wrinkled old ivory dealer, "but we can make no move till the cave is located. If they suspected we were after it, they would soon move it to another hiding-place or even pack it cross-country to the Nile and ship it out by the Mediterranean."