Skirting the stream, where flocks and herds stood gazing at their own images and others drinking of the transparent waters, we found the river, growing wider, opened into a spacious lake which was half surrounded by a rising hill. From the lake, higher than the river, ran a glittering cascade and over the pendant rocks fell luxuriant vines and creeping plants. At the opposite extremity of the lake, which by its pure waters exposed the bright yellow pebbles on which it wantoned, two streams ran towards the right and left of the hill and lost themselves amidst the groves, pasture and hillocks of the adjacent country. The prospects around us were beautiful and enchanting. Lofty trees threw a delightful, welcome shade, and the hill-side seemed covered with flowering shrubs, which grew irregularly except where a torrent from the summit, now dry, had during ages worn out a deep hollow bed for its rapid passage and descent.
There were no roads or beaten paths in this secluded portion of the royal domain, neither could there be seen any traces of habitation.
"Deep in yonder lake," said Omar, drawing up his horse suddenly and swinging himself from his saddle near the spot where the waters, springing from beneath some green, moss-grown rocks, fell with gentle music into the river—"deep in yonder lake there lies a hidden mystery."
"A mystery!" I cried. "What is it?"
"Have patience, and I will reveal to you a secret known only to myself and to the Naya; the secret that I told you must be preserved."
"But you say it is buried beneath these waters!" I exclaimed, puzzled. "How will you reveal it?"
"Watch closely, so that if occasion arises you will remember how to exactly imitate my movements," he answered, and when we had tethered our horses, he led me away from the edge of the lake up the hill-side some distance to where a number of points of moss-grown rock cropped up out of the turf.
After searching among them for some minutes he suddenly stopped before one that rose from the ground about three feet and was perhaps ten yards in circumference, examining it carefully, at last giving vent to an ejaculation of satisfaction.
"You see this rock, Scars!" he cried. "Does anything about it appear to you remarkable?"
I bent, and feeling it with both my hands, carefully examined its side, top and base.
"No," I answered, laughing. "As far as I can detect it is the same as the others."
"You would never guess anything hidden there?" he asked, smiling.
"No."
"Well, watch and I'll show you." And with these words the Naba of Mo approached the rock at a point immediately facing me, and placing his hands upon the side, about two feet from the ground, drew out bodily a portion of its lichen-covered face about eighteen inches square, that had been so deftly hewn that when in its place none could detect it had ever been removed.
Peering into the cavity thus disclosed I saw, to my surprise, what appeared to be a small iron lever, thickly rusted, descending into some cog-wheeled mechanism of a very complicated character.
"Now, watch the lake while I reveal to you its mystery," my companion said, placing his hands upon the lever. With a harsh, grating noise it fell back beneath the weight he threw upon it, and the harsh jarring of cog-wheels revolving sounded for a few moments beneath our feet. Then, as he set the mechanism in motion, my gaze was fixed upon the lake and I stood aghast in wonderment.
As the lever was drawn and the rusty cogs ran into one another, the whole mass of rock damming the lake above the small cascade where it fell into the river, gradually rose, like a great sluice gate, allowing the waters to escape and empty themselves, roaring and tumbling, into the winding river beside which we had journeyed. It was an amazing transformation, as imposing as it was unexpected. A few seconds before, the river, shallow and peaceful, fed by its tiny cascade, rippled away over its pebbly bed; now, however, with the great volume of water from the lake it rose so rapidly that the swirling, boiling current overflowed its banks, sweeping everything before it.
Nor was this the only result of pressing the lever, for at the opposite end of the lake a similar outlet opened, and as I looked I saw the water falling with a rapidity that was astounding. Hydraulic power was evidently known to these strange semi-civilized people, yet the actual means by which the lake was so rapidly emptied I was unable to discover, all the machinery being hidden away in some subterranean chamber.
"By what cunning device is this accomplished?" I inquired of Omar, who stood regarding the disappearing flood with satisfaction.
"This mechanism was invented ages ago by one of my ancestors," he answered. "Its exact date no man can tell. But here water is given mastery over itself, and so careful was its constructor to preserve the secret of its existence that the slaves and workmen, all criminals, were kept close prisoners during the whole time they were at work, and on its completion they were all, without a single exception, killed, in order that none should know the secret save the reigning Naba and his heir."
"They were murdered then!"
"They were all criminals who for various serious crimes had been condemned to death. It is said they numbered over two hundred," Omar answered.
But even as he had been speaking the water of the lake had so drained away that its clean stony bottom was now revealed, the pebbles being exposed in large patches here and there, while the deeper pools remaining were alive with water-snakes and fish of all kinds. There seemed but little mud, yet in the very centre of the great basin was a patch of pebbles and rock higher than the remainder, standing like a small island that, before the lever had been touched, had been submerged. Leading the way, Omar descended to the edge of the lake, skirted it for some little distance, until he came to a long row of flat stones placed together, forming stepping-stones to the miniature island.
"Come," he said. "Follow me," and starting off we were soon crossing the bed of the lake, being compelled to advance cautiously owing to the slippery nature of the weeds and water-plants that overgrew the stones. On gaining the island, however, a fresh surprise awaited me, for Omar, halting amid the mud in the centre, exclaimed:
"Watch carefully, Scars. You may some day desire to act as I am acting; but always remember that here any undue hurry means inevitable death."
"Death! What do you mean?"
"Wait, and you shall see," he replied, as stooping suddenly he turned up the sleeves of his royal robe and groping with his hand in the mud, at last discovered an iron ring, green with slime, which, grasping with both hands, he slowly twisted many times. A hissing sound was emitted, as if the action of untwisting the ring relieved some heavy pressure, admitting air to a chamber that had been hermetically sealed. This surmise was, I afterwards learned, correct. The unscrewing of this ring caused the sides of a plate embedded in the mud to contract, and air, so long excluded, entered the mysterious place below.
In a few moments, having paused to wipe the perspiration from his brow, Omar, again grasping the slippery ring, gave it a sudden jerk and by that means lifted the covering from a circular hole descending into an impenetrable darkness, but bricked round like a cottage well in England, and having projecting pieces of iron, forming steps.
"Now," exclaimed Omar, as together we peered into the mysterious opening. "To descend at once would mean certain death."
"How? Is the air below foul?"
"Not at all. The ingenuity of my ancestor who constructed this place made arrangements to avoid all that. The danger arises from a contrivance he devised by which any person attempting to explore it and being unaware of the means to guard against death, must be inevitably swept into eternity. Now, in order to give you an illustration of this danger I will show you the result of any adventurous person stepping down."
Taking from the mud a long iron bar, which he observed incidentally was kept there for the purpose of guarding against death, he reached down the shaft and placing the end of the bar upon the third step, threw his whole weight upon it, saying:
"We will suppose you have descended until your feet stand upon this step. Now, watch."
As the weight fell upon the step it gave way so slightly as to be almost imperceptible, but suddenly from hidden cavities around the well-like shaft there came six rings of long, sharp steel spikes, set inwards, three above and three below, which, contracting as they came forward, met and interlaced. In an instant I recognised what terrible fate would be the lot of any adventurer who dared to enter that dark shaft. The action of stepping upon that fatal projecting iron released hydraulic pressure of irresistible power, and the unfortunate one, unable to ascend or descend by reason of the danger being above and below, must be impaled by a hundred cruel spikes, sharp and double-edged like spears, while the bands whereon they were set must crush his bones to pulp.
I looked at this terrible device for producing an agonizing death and shuddered. The precautions taken to prevent anyone entering the place were the most elaborate and ingenious I had ever seen. Even if any person learnt the secret of draining the lake, the shaft leading to the mysterious subterranean place was unapproachable by reason of this extraordinary mechanical device.
During five minutes the spikes remained interlaced, then automatically they disengaged themselves, and slowly fell back into the cavity running round the brickwork, wherein they remained concealed.
Thrice again did Omar repeat this action of pressing the bar upon the step, each time with an exactly similar result, chatting to me the while. Then, when for the third time the spikes had fallen back into their places, he said:
"Now the secret to avoid this and lock the mechanism is to turn back this little lever and place it in this catch, so. This cannot, however, be done unless the step has been pressed three times."
And bending over he showed me another tiny lever thickly encrusted with rust, secreted behind a movable brick in the first tier below the lake's bottom. This he placed in position, securing it in a niche so that it became immovable.
"Now," he said, "we may descend without fear," and with these words knelt down, and after lighting a torch he had brought with him, commenced the descent into the cavernous gloom. I quickly followed, my feet resting for a brief instant upon the fatal iron projection, but no spikes came forward, for the terrible mechanism was now locked. Deep down into this circular shaft we went, the smoke and sparks from Omar's torch ever ascending into my face as I lowered myself from rung to rung, until at last, at considerable depth, we found ourselves in a kind of natural cavern. The place seemed damp and full of bad odours, to which submitting with patience we, by a long passage, sometimes crawling under rugged arches, sometimes wading in mud and dirt, attained the end of the cavern, where we stumbled on some narrow steps; but the torch shed little light, and we became nearly suffocated by the noisome vapours.
"I thought you said the air was fresh here," I exclaimed good-humouredly to my companion.
"So I did," he answered. "I cannot make out why it has become so foul. The air-holes must have become accidentally stopped up."
The widening ascent was so intricate and clogged with dirt and rubbish that we worked like moles in the dark; nevertheless, by diligent industry we gained ground considerably, yet as we endeavoured to mount, the slimy steps slipped from under us, and ever and anon we would come tumbling down with a weight of dirt upon us.
After various labours, however, we suddenly entered a great cavern, quite dry. From its roof hung great stalactites that glittered and sparkled in the torch's uncertain light, while around the rough walls of this natural chamber were heaped in profusion great heavy chests of iron and adamant.
With the torch held high above his head Omar rushed across to the pile and bending, examined one chest after the other. Then, raising himself as the truth suddenly dawned upon him, he cried in a hoarse, excited voice:
"By the power of Zomara, we have been tricked!"
"Tricked! How?" I gasped in alarm.
"Cannot you see?" he wailed. "This, the Treasure-house of the Sanoms, has been entered and its contents, worth a fabulous sum, have been extracted! See! Each trunk has been forced by explosives!"
I gazed eagerly where he directed, and saw that the trunks of iron and stone had been blown open by gunpowder, for on each remained a blackened patch, showing plainly the means used to force the strong chest wherein reposed the magnificent jewels, the vessels of gold, and the historic gem-encrusted and invulnerable armour of the Nabas of Mo.
"Then this is the place the secret of which the villainous old Arab, Samory, endeavoured to wrench from you by torture," I exclaimed, gazing round the grim, weird cavern.