For a long distance the hostile tribes were found to speak practically the same language, and Dr. Wolf's interpreter was the most important person on the boat. The natives thought the strangers could not understand them, and so they freely talked of their plans for attacking them. One day, when Dr. Wolf stopped to repair the En Avant, natives armed with bows and arrows speedily surrounded the steamer. They were not a bit afraid, and drew right up alongside. Their chief, Tongolata, told his warriors that these strangers were entirely at his mercy. Why, he couldn't see a single weapon among them! He looked at a gun with great curiosity. "Whatever the thing is," he finally declared, "it is not a weapon." He told his people it would be easy enough to kill these folks and seize all the strange and beautiful things they were showing. Things were beginning to look squally. More canoes were coming every minute. Dr. Wolf was a man of peace, and would not take a human life unless it was necessary to save his own men. But he must do something to over-awe these savages. He showed the chief a revolver, and told him it carried lightning that killed men. Then he held the weapon so that its discharge would hurt no one, but the barrel was close to the King's ear. He pulled the trigger, and the chief fell to the bottom of his boat, stunned by the terrible noise. All the natives were stupefied with astonishment and fear. The chief held on to both his ears until he decided that he was not hurt, and then he declared that he was the white man's good brother, and honored his new friend with a present of two chickens. Some explorers—very few, it is hoped—would have fired into the crowd under such circumstances. But men who are fit to be trusted among barbarous peoples have very often been able to insure safety when danger threatened by some such expedient as that which Dr. Wolf adopted.
The actions of some of these tribes when they first caught sight of the wonderful "fire-canoe" were very curious. The Bena-Jehka, for instance, threw themselves on the ground—not in fear, however, for they greeted the coming vessel with a hearty clapping of hands. The friendly natives were greatly tickled to find that this puffing boat was no match in a race with their canoes. They could travel all around her; and no wonder, for some of their dugouts were nearly ninety feet long—twice the length of the En Avant—and eighty paddlers standing erect in the larger boats made them fairly skim through the water. Sometimes fifty of these canoes were darting here and there, playing tag with the slow steamer, and dodging her every time. It was great sport for the friendly natives of the south bank, and the hostiles across the river did not know how much fun they were missing. None of these people had ever heard of a gun.
The African telephone was busy, as the steamer advanced, carrying the news up the river. The deep notes of the big drum, or tomtom, are the signal of great events in those parts, and crowds flocked to the banks long before the vessel puffed into view, straining their eyes for the first glimpse of anything wonderful or menacing. These signals, however, do not compare with the ingenious system perfected by a few small tribes in the Cameroons, West Africa, where the sounds on the drum represent syllables and words, and so grow into sentences, like the ticks of a telegraph instrument. Only about two hundred natives have been instructed in the art, and the secret is so carefully guarded that no white man is yet able to interpret these drum-beats, which carry verbal messages from one drummer to another as fast as sound travels.
Far up the river Dr. Wolf discovered some remarkable houses built in the branches of trees. Many African tribes, like the people of New Guinea and the Solomon Islands, in the Pacific, build platforms high up in the trees, so that their lookouts may quickly discover the approach of an enemy, or their women and children take refuge among the branches in time of danger. An invention of the white men is destroying this custom of building tree refuges, and you can easily guess what it is. Traders have introduced many guns among the natives, and the women find that their rude perches in the air are no protection against bullets. But the tree houses Dr. Wolf saw serve a different purpose. The natives live in them to keep out of the wet when the land is flooded. A platform is firmly lodged in the widest fork of a tree, and a roof is built on the top of uprights that rest on the platform. The boys and girls are a happy lot when the floods subside and they can press the ground again with their bare feet.
It was a joyous lot of black men whom Dr. Wolf restored to their homes in Angola, after they had served him well for many months while he was adding this river to the maps. But on the way home they had one serious disappointment. One day they saw a group of baobab-trees, the largest plant that grows in Africa. It was many a day since they had seen the familiar sight. "Hurrah!" they cried; "we are near the sea. We are in Angola again." But they were still far from Angola.
These humble negroes helped to prepare the way for the busy white stations that are now planted on the Sankuru's banks. They should have their share of credit for the good work that was done.