It is not necessary to describe in detail the passage up the Kasai, from the place where the leopard had been wounded to Date Palm Island, which was where M'WanÉ decided to disembark. During that voyage, which occupied two and a half days, they passed a mangrove swamp upon the southern bank, which the Fan chief pointed out as the place where the Hidden River joined the Kasai.

No one would have guessed it. The short, stunted trees were packed so close together that their branches formed a kind of solid roof which appeared to extend for miles. Underneath, there was darkness as of night. There was nothing to suggest that another river here joined the larger stream. The Kasai did not narrow above the swamp, nor was there any change in the colour of the water or the strength of the current.

Date Palm Island lay a day's journey by canoe above the mangrove swamp. The name of Date Palm Island was given by Edward Harden the moment he set eyes upon the little rocky islet in mid-stream, upon which stood a solitary tree. It was the custom of this explorer to name the natural features he discovered; and it was he who was also responsible for the names of other places of which, in course of time, we shall have occasion to tell, such as Solitude Peak and Hippo Pool.

In addition to the Loango boys who composed the crews, the party now included M'WanÉ, the Fan chief, and four of his most trusted warriors. It was on the occasion of this journey on the Upper Kasai that Edward Harden made one of the mistakes of his life. M'WanÉ travelled in the first canoe with themselves, and his four warriors in the other canoe which followed. Both Harden and Crouch had a natural wish to keep the object of their journey a secret. Neither knew that one of the boys in the second canoe could both speak and understand the Fan dialect, and it was he who told his companions that the Hidden River was their destination. Still, no one suspected that the secret was out, until they had unloaded all their supplies and ammunition at Date Palm Island, where they decided to form their base.

In this district, the general course of the Kasai lies due south-west. From the mangrove swamp on the southern bank, the valley of the Hidden River lies, more or less, in a direct line from north to south. M'WanÉ had known the Hidden River in the old days, before the Fire-gods came into the country. He said that there was a good portage across country from Date Palm Island to Hippo Pool, which was the nearest accessible point on the Hidden River above the rapids that flowed through the Long Ravine.

They decided to leave one canoe on the island, in charge of four of the Loango boys. The remaining natives could be employed in carrying the lighter of the two canoes, and a sufficiency of stores and ammunition across country to the Hidden River. The indignation of Crouch may be imagined when the boys struck in a body and refused to undertake the portage.

Edward used his greatest powers of persuasion; Crouch threatened and abused. They answered that word of the Fire-gods had been carried even as far as the Coast, that they had never bargained to sell their lives to the Englishmen. None the less, they expressed their willingness to remain upon the island until the party returned.

Crouch turned to M'WanÉ.

"And do you, too, go back?" he asked.

The chief shook his head, and smiled.

"My men and I will stand by the White Wizard," he answered. "A Fan holds to his word."

Crouch slapped the chief upon the back, and then went on to explain to the boys that if they helped with the portage, they would not be asked to embark on the Hidden River, but could return to Date Palm Island. After some discussion, they agreed to this; and as much time had already been wasted, Harden and Crouch decided not to start until daybreak the following day.

According to Edward Harden's diary, the portage lasted two weeks and three days. They were obliged to force their way through virgin forest. It was frequently necessary to cut down with axes and billhooks the tangled undergrowth and creepers that wove themselves amid the trunks of the trees, in order to make room for the canoe to pass. Some days they did not cover more than a mile, though they were working from dawn to sunset. But towards the end of the journey the passage became easier, by reason of the fact that they found a watercourse, which they followed, until they finally came forth into the sunlight at Hippo Pool.

When they first looked upon it, it was as if, indeed, there were an air of mystery in the valley of the Hidden River. The silence that reigned upon its surface was intense. The atmosphere seemed several degrees hotter even than the forest. The name Hippo Pool was given because, immediately on their arrival, Edward Harden, who was leading, shot a hippopotamus which he found asleep upon the bank. They were glad enough of the meat for the natives, who would require provisions on their journey back to the Kasai.

The next morning the Loango boys left in a body. They were glad enough to be off. And soon afterwards the canoe shot out from the bank.

Their progress was painfully slow. M'WanÉ and his four followers worked continually with the paddles, assisted in turn by Harden and his nephew. As for Crouch, he was always the look-out man. His only eye was quick and keen as that of a falcon.

Hour by hour they toiled into the Unknown, until the sweat poured from their faces and their hands were blistered in the sun; and the blisters would not heal, because of the insects that followed in a crowd. The jungle grew more magnificent and wild as the river narrowed. The character of the trees changed, and of the undergrowth--all became more luxuriant, more profuse, until they found themselves in a land where Nature was something fantastic and superb.

It was on the third day after they had set out from Hippo Pool that they turned an angle of the river, and came on a sudden into a cup-shaped valley where there was but little vegetation. A circle of granite hills stood all around them, and in the centre on either side of the river was a plain of sand. Crouch turned in the bows and pointed to something ahead, and at that moment the sharp crack of a rifle echoed in the stillness, and a bullet sped into the water a few inches from the bows of the canoe.