The folding tubs they all used were more like little canvas rooms, open at the top. The crew of their launch consisted of two Bantus. One of these helped John fill the tub by the simple method of standing on a chair and pouring water on the head of the occupant of the tiny chamber after his clothes had been thrown out.

The boys were watching the proceedings and intended to follow the captain's example. As he finished he told the Bantu boy to hand him his clothes and stretched out an arm through the slit in the canvas walls. As it happened, this opening faced the boys.

The Bantu held up the bundle of clothes. As Captain Montenay took them the boys saw the black recoil suddenly and sink to his knees with a low groan, his face gray. Burt immediately leaped to his feet and caught the Bantu but the latter thrust him away and staggered back to the engine. Here he sank on a locker and buried his face in his knees.

"Well I'll be jiggered!" exclaimed Burt half angrily. "What's the matter with him?" He was about to call his uncle who was up under the forward awning when Critch caught his arm.

"Shut up!" the red-haired boy whispered excitedly. "Come over here." When they reached the rail he turned on Burt. "Didn't you see it, you chump? What's the matter with you, anyway?"

"Me?" gasped Burt, bewildered by this sudden attack. "Say—"

"Thought you saw it sure," interrupted his chum hurriedly. "Didn't you see Cap'n Mac's arm?"

"No," returned Burt shortly. "Like any other arm, ain't it? I was lookin' at the sick nigger."

"Sick nothin'," retorted Critch. "Cap'n Mac's got a shoulder on him enough to scare a cat! When he shoved the canvas back I could see it all twisted up an' dead white, with a big red scar on the corner o' the shoulder. That nigger wasn't sick—he was scared!"

"Scared!" Burt stared at Critch and then turned to look at the Bantu boy crouched on the locker. "Golly! Mebbe he is! Say, what was the scar like?"

"Looked to me like a cross but I didn't see it well. Come on, we'll ask the coon. He talks French some."

They stopped beside the Bantu. The second black was sitting in the bow at the wheel and had noticed nothing. Critch took the black by the shoulder and gave him a shake, while Burt addressed him in French.

"Wake up, boy! What scared you?"

The Bantu gave one terrified shudder and his eyes were rolling wildly as his head came up "Pongo! L'emblÈme de Pon—" he began with a frightened gasp and then stopped. His face resumed its normally blank expression and he glanced around quickly.

"What's Pongo?" questioned Burt. "What do you mean by the sign of Pongo?"

"No savvy, m'sieu, no savvy." The Bantu shook his head and absolutely refused to say another word in spite of threats and commands.

"Come on," said Critch disgustedly. "He's wise to something but he won't let on. There's Cap'n Mac. Shut up."

They rejoined the captain and Mr. Wallace in the bow. Evidently the Scotchman had neither seen nor heard anything unusual, for he at once plunged into discussing plans with Mr. Wallace.

"Look here," he said finally. "I can't give up that cook o' yours, Wallace! Ye've got a good Scots name too. S'pose we make one party?"

"One party!" exclaimed Mr. Wallace. "I thought you were going more to the east?"

"Aye, but I ain't over parteec'lar. Mind, I'm no sayin' I'll go clear to the Makua wi' ye, but I may."

"Here's John with the dinner," said Mr. Wallace. "We'll talk it over while we eat. Looks mighty good to me, Montenay! I'd like you to go with us if you will."

"Hello, what's this stuff?" cried Burt as he leaned over his bowl and sniffed suspiciously. John stood by with a triumphant grin.

"Smells good," commented Critch. Captain Mac, as they had come to call him, winked at Mr. Wallace.

"It's vera good for fever," he said solemnly. "They make it out o' chopped snakes an' nigger bones."

The boys looked up in dismay but were reassured by Mr. Wallace's smile and John's ever present grin. Burt put the question to the latter.

"Palm-oil chop, sar! Chicken chop-chop, palm-oil, peppers, hother t'ings halso, sar. Hit be good."

The boys cautiously sampled the concoction and found it to be new but not unpleasant. Before they had been in the country another week they were vociferously demanding palm-oil chop from John every day. The launch tied up at a plantation dock for the night and at daylight proceeded on her way.

"Hello!" exclaimed Critch as he emerged from the tiny cabin for breakfast. "That's funny! Thought it was in my outside pocket."

"What's bitin' you?" asked Burt with a rather sickly smile. He also was fishing in his pockets.

"My compass—it's gone!"

"Same here," confessed Burt after a moment. "I'll be jiggered! My coin's all right!"

"What's the matter?" inquired Mr. Wallace. He was just coming out and behind him was Captain Mac. The boys explained their strange loss and Montenay frowned.

"That's queer," he said thoughtfully. "Mine's safe. How's yours, Wallace?"

"Here." Mr. Wallace produced his own silver-set compass from an inner pocket. "You've probably dropped 'em around the cabin, boys."

The two turned and vanished hastily but reappeared shaking their heads. The missing instruments were not to be found on board, although a thorough search was made of the launch and men.

"Na doot they were stolen," said Captain Mac as they sat at breakfast. "These blacks will steal anythin' that ain't nailed down, an' they were prowlin' all about last night. Well, we'll get new ones at Makupa from the trader when we get there to-night."

"It's decidedly queer, Montenay!" Mr. Wallace looked out over the river with a perplexed frown. "Why should these two compasses vanish, when nothing else in the cabin was touched? I don't like it."

"Ye know what ju-ju is, o' course?" Captain Mac leaned back easily in his chair as the American explorer nodded. "The Bantus think compasses are ju-ju."

"What's that?" asked Critch.

"Anything they don't understand and that savors of witchcraft or mystery is ju-ju," explained Mr. Wallace. "In that case, Montenay, our compasses will be looked upon as the gods of a Bantu village, eh?"

"Aye. Let's get our business done with, Wallace." Montenay deftly rolled himself a quinine capsule and swallowed it. "What d'ye say? Shall we combine or no?"

"I don't see why we shouldn't," returned Mr. Wallace thoughtfully. "We're both after ivory. One caravan will cut down expenses for each of us. You're not sure about making the Makua with us?"

"Well," replied the other slowly with a sharp glance at Mr. Wallace, "I'm no sure yet. There's some mighty queer country north o' here that I'd like to have a look at. Mind, I'm no promisin' anythin' whatever. I'll be free to come an' go."

"Of course," answered Mr. Wallace. "Then it's agreed, Captain! We'll leave Makupa together in the morning."

"Vera good. Now I'll be lookin' after a letter or so under the awnin' aft where the shakin' ain't so strong." Montenay rose and strolled aft and was immediately absorbed in his traveling writing-case. Mr. Wallace gazed after him reflectively.

"There's a curious man, boys! We're in luck to have him along. There probably aren't a dozen men in Africa who haven't heard of him and there probably aren't a dozen who know him outside of officials. He always travels alone. If he strikes in at Zanzibar or Nairobi he's likely to come out at Cairo or the Cape."

"Strikes me as a good sport," agreed Burt heartily. "He don't say much but I'd hate to monkey with him when he gets mad. Say! Ever hear o' Pongo, Uncle George?"

"Pongo?" repeated the explorer as he stared hard at Burt. "Pongo? No, don't think I have. What is it?"

The boys explained what had taken place the previous afternoon but to their surprise Mr. Wallace frowned disapproval. "Whatever it is, boys, it's his business. If you'll look at his arm you'll see a dozen scars. I have a few myself. That's where a native chief cuts a gash in his arm and ours, the cuts are rubbed together and we are then termed 'blood-brothers.' It may have been some such mark that scared the black boy."

"No it wasn't," asserted Critch positively. "It looked like a cross. Wasn't cut either. Looked like a burn more than anything else."

"Then forget it," commanded Mr. Wallace decisively. "It's none of our business. I must say that Montenay's mighty indefinite though. He says he's after ivory and wants to have a look at the country. But if I know anything he's not worrying about ivory this trip."

"Why not?" asked Burt. "D'you mean he's lying?"

"Lying is a strong term, Burt!" smiled his uncle. "It's not a nice word to use either. No, I think he's keeping us in the dark about his own projects. Probably he has some new animal or some new tribe he wants to be sure of getting all the credit for discovering. Naturally he wouldn't want to run any risk of our cutting in on him."

Just then the subject of their discussion rejoined them and the topic was changed. On up the river they went all that day while the big canoes followed closely with the paddling-chants of the men rising from time to time. The breeze created by their motion relieved them of the clouds of mosquitoes and other insects but the heat was so great that it even affected John to some extent.

Just before sunset they reached the Makupa station. This consisted of a large native village dominated by the State trading post, a corrugated iron building whose whitewashed walls contrasted strongly with the palm thatched huts of the blacks all around. The trader met them at the landing and proved to be a Belgian, pleasant and courteous in every way.

They spent the night here. In the morning they were up before daybreak and Mr. Wallace mentioned the compasses as they were dressing. At that moment Burt was speaking to Captain Montenay, and he saw a peculiar light flash into the little explorer's face when his uncle spoke. That look puzzled Burt somewhat. He was still more puzzled when Montenay rushed through his dressing and hurried from the room. The sudden change in the man had evidently been caused by his uncle's words, but Burt could not see any connection whatever.

When they entered the lamp-lit dining room for breakfast they found the agent and Captain Mac together. The former sprang up and greeted them effusively, hastily stuffing something into his pocket that looked to Burt like banknotes. Still, the boy remembered his uncle's words of the day before and made up his mind not to bother about other people's affairs.

"Oh, the compasses!" ejaculated Mr. Wallace as the black boys brought in fruit and coffee. "Lieutenant, we lost two compasses coming up the river. It would be a great assistance if you would sell us a couple from your stores."

"Alas!" An expression of dismay rose to the Belgian's face and he spread out his hands helplessly. "My friend, I am grieved deeply to have to inform you that we have none! A trading party came down the river last week and completely cleaned me out, even to my own instrument. I am desolated, my heart is torn, but it is impossible!"

A sudden suspicion flashed across Burt's mind but as he glanced sharply at Captain Mac he dismissed it. Montenay was the picture of dismay, but to all their suggestions and queries the Belgian only returned a "desolated" shrug.

"Well, never mind." Mr. Wallace smiled at Montenay in resignation. "We still have ours. Two should be enough. Now make a good breakfast, boys! We eat from chop-boxes after this."

With sunrise the caravan started north from the station. The river bottom was low but Captain Mac asserted that after a day's journey they would find themselves on the higher plains, and this proved quite true. On the second day they entered the great forests and left behind the half-civilized tribes. As they drew up to the top of a hill-crest that rose among the trees Critch caught Burt's arm and pointed ahead to where the jungle thinned out.

"There we are, ol' sport! Look at 'em, just look at 'em!"

And Burt saw through his glasses a number of black groups of animals, grazing and moving slowly about.

"What are they, Uncle George?" he cried in high excitement to Mr. Wallace who was also looking through his glasses.

"Hartebeest, bushbuck and antelope," replied the explorer calmly. "If I'm not mistaken there's a rhino in that patch of bush about two miles to the right—see it? John, O John! Get those gun-boys on deck, will you?"