The naturalist looked wistfully at Frank.
"I suppose there would not be the least objection to my availing myself of your assistance in getting up the river," he said, blinking behind his spectacles like an old bat who has unexpectedly emerged into the sunlight. "I have only two canoes and as I carry my own attendant I shall be no trouble."
"We shall be delighted to accommodate you," rejoined Frank heartily, "but I shall have to place one restriction on you. When we reach our destination we must part company as we have work to do of a confidential nature. Our employer, Mr. Barr—"
"Old Luther Barr," burst out Professor Wiseman suddenly.
"Why, yes," rejoined Frank, rather taken aback, "you know him then?"
"I—I have heard of him," replied the other with a slight hesitancy which was, however, so faint as to be hardly noticeable. The voice of Madame Desplaines summoning them to breakfast broke off any opportunity for further questions on a matter that plainly, for some strange reason or other, seemed to have heartily interested—even disturbed—the naturalist. Frank felt troubled for a moment at the idea of having let Professor Wiseman form a portion of their party even for a short distance. But he dismissed the idea almost instantly. The queer expression that passed over Professor Wiseman's face at the mention of the ivory trader's name might have simply been due to astonishment at hearing it again. Still Frank decided to keep an eye on Professor Wiseman.
The conversation at breakfast naturally enough dealt with the little known country the boys were to penetrate. Then it was for the first time that they heard mention of the mysterious tribe of the Flying Men who were reported to be equipped with rudimentary wings—like those of an undeveloped bat with which they managed to flit from tree top to tree top like true flyers.
"Oh, come," laughed Billy, "I've heard of tailed men and white Africans with red top-knots like Lathrop, but a race of winged men is coming it too strong."
"Laugh if you like," declared Professor Wiseman who had brought up the subject, "but some time ago I articulated a skeleton brought me by an Arab slave trader and found extending from the shoulder blade two distinct bony frames which had in life apparently been covered with a thin fleshy substance of leathery like tenacity stretching thence to the wrists. I asked the slave trader where he had found the skeleton," went on the savant, "and he told me he had come across it at the foot of a giant silk cotton tree in the Bambara country."
The boys exchanged glances. It was to the Bambara country—the country of the legendary Flying Men—that they were bound.