The Project Gutenberg eBook, The Wonder Island Boys: The Mysteries of the Caverns, by Roger Thompson Finlay This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org Title: The Wonder Island Boys: The Mysteries of the Caverns Author: Roger Thompson Finlay Release Date: February 17, 2007 [eBook #20614] Language: English Character set encoding: ISO-8859-1 ***START OF THE PROJECT GUTENBERG EBOOK THE WONDER ISLAND BOYS: THE MYSTERIES OF THE CAVERNS*** E-text prepared by Joe Longo, Mary Meehan, and the Project Gutenberg Online Distributed Proofreading Team (http://www.pgdp.net/c/) The Wonder Island Boys THE MYSTERIES OF THE CAVERNS ROGER T. FINLAY ILLUSTRATED THE NEW YORK BOOK COMPANY New York Copyright, 1914 "The professor was reading the scrap, and silently handed it to George" CONTENTS CHAPTER I. Mysterious Disappearance of the Team The runaway team. Circumstances leading up to the present condition. The singular occurrences. Examining the tree. The search for the yaks. Red Angel as a scout. On the tracks. Losing the trail. Red Angel's discovery. The wrecked wagon. The lost weapons and ammunition. Breaking in new steers. The planting program. Different plants and soils. Prospecting for ores and vegetation. Discussing hunting trip. How people of different countries select soils. Wild fruit and vegetables. Lessons from the actions of their animals. Propagation of fruit and vegetables. Chemical changes produced by different soils. The wild potato. CHAPTER II. Working on the New Boat Determine to bring in the newly discovered lifeboat. Trip to South River. Finding the broken yoke of their team. Recovering the lifeboat. Uses for the bolo. Decision to row the boat around the point. Making more guns. Preparing new tools. Alloys and their uses. Hardness of metal. Bronze. Ancient guns. Manganese. Making stocks for the guns. Commencing the hull of the new boat. Size of the vessel. About shape or form of hulls. Momentum. Resistance. Red Angel's attempt to whistle. Amusing performance. Teaching Red Angel accomplishments. Vibration, the universal force. CHAPTER III. The Hidden Message The new yoke for the yaks. Some of the mysteries. Discussion concerning future discoveries. Rainbows. Musical pitch and colors. Reflection and refraction. Riding the yaks. Completing some of the guns. The trip after the wrecked wagon. Finding their runaway team. Accounting for their disappearance. Prospecting. Sugar cane discovered. Sorghum. The Tamarisk. Rigging up the lifeboat with sails. Discovery of a hidden message in the lifeboat. Examining the place where it was found. Determining the time when the message was written. Rushing preparation of guns and ammunition. Galena. Lead. Getting rid of the sulphur. Making bullets. CHAPTER IV. The Terrible Monsoons Completing the guns. Description of the new ones. Polishing grit. Emery. Corundum. Laying the keel of the big boat. Terrible winds. The monsoons. Trade winds. Length of summers north and south of the Equator. Disappearance of the flag from Observation Hill. George and Angel's hunt for the flag. Disappointment. Angel finding the flag. Angel's laugh. Facial expression in animals. Brass. The form of bullets. Why pointed at one end and hollow in the other. Rifling guns. Spiral movement. Molds for castings. The Professor's desire to fully explore the cave. Weaving the sails for the new boat. Angel's work on the loom. CHAPTER V. The Voyage for the Benefit of Angel, and the Discovery Completing the hull of the new boat. Making manilla rope. Decide to take Angel along. Enticing him aboard. His consternation. Rounding the cliffs. Discovering their first boat among debris. Taking it along as a trailer. Sailing up Cataract River. Evidence that their boat had been used by some one. Proof of its use by the natives. One of the signs of civilization. Leverage. Fulcrum. Mechanical powers. Delay of voyage owing to weather. Tourmaline. Harry's invention. The bamboo tubes. Testing how fast the guns could be loaded and fired. Cartridges. The marine works. The boats. Three cheers for the new ship. CHAPTER VI. The Gruesome Finds in the Cave The cave. Taking the boat to explore the interior. The air pocket. A board for charting the cave. The boat on the wagon. Entering the cave. The lights. Returning for the boat. The peculiar noise at the cave entrance. Methods for searching the cave. The domed chamber. Making a circuit within it. The outlet. The second chamber. The chalk icicles. Limestone. Volcanic action. Carbonic acid, and what it produced. The caves of the world. What is learned in searching caves. Their archaeological knowledge. A peculiar formation in the large chamber. A platform within a recess. Skulls and skeletons. Ancient weapons. Evidences of a terrible conflict. Musket balls. Dirks and unknown forms of weapons. Singular copper receptacles. Curiously wrought knives. Articles of furniture. Decayed clothing. Kitchen utensils. Why the cave takes care of the smoke. CHAPTER VII. The Treasures of the Cave The couch in the recess. Chests of gold. A pirates' lair. The ancient coins. Peculiar articles of ornament. The lid with mocking lock. Rings; bracelets. The buccaneers. The sermon. Ghastly relics. A perceptible movement in the atmosphere. Startling supposition. A possible outlet in the side of the hill. The slab of carbonate. The writing on it. An accident and the finding of other skeletons. The light shining into the cave. Discovery of the outlet. View of the cataract from the opening in the hillside. The boat in the cave. Taking it out by the hillside opening. The Professor's search. Return of the boys with the team. Re-enter the cave. The Professor lost. Hunting in the unknown passages. Return of the Professor. Taking two of the skeletons to the laboratory. CHAPTER VIII. Removing the Vessels from the Caverns Completion of the boat. Making a trial voyage. Rounding the cliffs. Trip to the south. The forests and the mountains. On the south coast. A raging storm. Seasickness and dizziness at great heights. The calcareous slab from the cave. The letters on it. Photography. Reagents. Photographic light. X-rays. Taking the copper vessels from the cave. Gathering up the bones. Evidences of the strife. Spanish inscriptions. Gold bullion. Silver ornaments and vessels. Decayed chests. The coins. Peculiar guns. Non-effective powder. Disappearance of Angel. Return of Angel with a rusted modern gun. Iron or steel guns. Powder as a factor in making weapons. CHAPTER IX. Making Electricity Their present condition. What they had accomplished. Working for love. Contemplating the hoard in the cave. Selfishness at the bottom of the pirates' lives. Gathering sugar cane. Honey, and its uses in ancient times. Beets and various tubers. Fattening properties. Nitrogenous matter. The load of cane. Making a sugar mill. Lime in sugar-cane juice. Clarifying sugar. A candy pulling. Granulating sugar. The earth as a magnet. Electricity. Positive and negative. Magnetic poles. Likes and unlikes. Making a magnet. Retaining magnetism in a bar. CHAPTER X. Starting on the Voyage to the West A barometer. Air pressure. A compass. The atmosphere. Dry weather. Observing weather conditions. Providing compartments in the boat for provisions. Bedding. Water supply. Faith. Preparing a tablet for the Cataract. A terrific storm. A delayed departure. How delays have often proved valuable to investigators. Starting the voyage to the west. Striking a course. Observations on speed. Going with the wind. Tacking. Angles of incidence. The action of air on a surface. Determining the pressure of air by its velocity. Flying machines. Time and speed in a vessel. Qualities necessary in a sailor. CHAPTER XI. A Terrible Voyage and the Shipwreck The shadows of night. Recalling memories of their shipwreck. The charting board. Cardinal points of the compass. How direction traveled is laid out on the chart. Measurement by angles. A weary night. The watches. The wind changing. The second day. Cliffs beyond. Sailing against the wind. Rounding the northern point. The fourth day. The increasing gale. Night. The lights to the south. The gale turning to a storm. Driven back. A night without sleep. An appalling monsoon. Springing a leak. The Professor exhausted. Danger ahead. The cliffs. A maelstrom in sight. Averting the danger. Recovery of the Professor. Steering for shore. Striking the beach. The vessel shattered. Stranded miles from home. Taking up the march. Putting an inscription on the boat. Nearing home. CHAPTER XII. The Return Trip. The Orang-outans The blackened fire space. Discovery of their own camp in the forest. An adventure in the woods. A huge bear. George's shot. Charging the Professor, and his shot. Attacking George. Safety behind a fallen tree. Search for the luggage. The cries of Angel. The bear finding their packages. The bear making use of their things. What they had left. The yellow pear. Guava. The coffee tree. Cherries. Gathering coffee berries. How Angel made himself understood. His excitement. The discovery of a number of orang-outans. Red Angel visits them. He is not welcomed. Return of the animal. The clearing in the woods. Recalling the fight of the bears over the honey. CHAPTER XIII. The Strange Visitor The flag on Observation Hill. Approaching Cataract. The alarm by Red Angel. The house intact. Discovery of a man at the stable. His peculiar actions. Lost memory. Aphasia. Unable to speak. Recognizing the signal flag on the strange man. Provided with clothing. A peculiar malady. The instinct of self-preservation. Going with George to Observation Hill. The actions of a sailor. The stranger visits the workshop. Expert with the use of tools. Projecting an exploring trip by land. Naming the stranger John. Startled at sound of the name. Mechanically performing work. Examining the skulls. CHAPTER XIV. An Exciting Trip to the Falls The food supply. Butter. Cream. Centrifugal motion. Difference in specific gravity between cream and milk. Making a cream separator. Vegetables. Onions. Chives. The stranger as a prospector. Procuring samples. Peculiarities of his malady. An exciting encounter with a bear. John's skill as a hunter. Another honey tree. Killed with a spear. The bear pelt. Visiting the falls. Action to indicate that John recognizes the falls. CHAPTER XV. The Story of the Cave Mystery about John. Humanity's search. The desire to know and acquire. Gathering supplies for an extended trip by land. The boys visit the cave. Determine to search the chamber visited by the Professor. Gorgeous calcareous hangings. The ghosts of past centuries. Gold and silver vessels. Skeletons. A recess. A row of chests. Spanish guns. The chained skeletons in the recess. An arsenal. The struggle. Locked in the embrace of death. Ancient origin of the cave. Paleontology. Stone and bronze ages. Atlantis, the great continent in the Atlantic, which disappeared. Story of the Egyptian priests. The actinic rays. Purifying action of sunlight. Bacteria. Glass houses. The eye. How it expresses character. Laughter. How it brightens the eye. Fishhooks. A fishing party. The salmon. CHAPTER XVI. Music and Animals Preserving fish. Why heat is used. The use of tin for cans. Music. The violin made by the boys. Violin strings; what they are made of. How they are prepared and treated. The concert. How the music affected Red Angel. John enraptured. How it touched him. The change in his eyes. The field mouse. How different animals are moved by music. The lion. Hippopotamus. Tigers. Monkeys. Momentary flashes of intelligence in John. Building a new wagon. Finding and making paint. Lead. Fermentation. Flax. Driers. Turpentine. Synthetic food. Analysis. Tubes for powder. Completing the guns. Stocking the wagon with provisions. Starting on the trip. Jack and Jill. The sixth trip. CHAPTER XVII. The Trip Through the Dense Forest The trip along Cataract River. The great forest. How Angel traveled. Reaching South River. Discovering a second falls. Where the debris on a seashore comes from. The jungle. Leaving the river. The two animals in the night. The camp aroused. A fight in the dark. The puma. The frightened team. The injured yak. Animal language. The panther. Trying to avoid the forest. Growing denser. John and Harry scouting through the forest. Blazing a trail. The hidden luncheon. End of the forest. Returning to the wagon. The noise in their path. The wagon following the trail. The injured yak improving. CHAPTER XVIII. Seeing the First Savages Teaching Angel. Finding a campfire. Determine from the conditions that it was recently made. Prospecting from the tops of trees. A climbing ring. How made and used. The climbing operation. Harry sees another forest to the south. Clear in the west. The wounded yak calls a halt. Resuming the journey. Harry in the grasp of a giant anaconda. John severs its body with a bolo. Boa constrictor. The python. The Cashew tree. Gum arabic. Seeing the West River. Discovering signs of habitations to the south. Course to be followed in meeting the natives. Hearing voices in the night. Crackling of twigs. A party of savages. The next morning. Examining the tracks made by the midnight party. Following the trail thus made. The open country. The first view of the inhabitants. GLOSSARY OF WORDS USED IN TEXT Other books from THE NEW YORK BOOK COMPANY LIST OF ILLUSTRATIONS "The Professor was reading the scrap, and silently handed it to George" "'We have probably found a pirate's lair, and here is the booty'" "The Professor walked toward him and held out his hand" "With a single stroke the body of the snake was severed above the last coil" List of Figures 1. The Broken Yoke 2. Top View of Boat 3. Side View of Boat 4. Cross Section of Boat 5. Force of Momentum 6. Red Angel 7. The Color Spectrum 8. Reflection Angle 9. The Hidden Message 10. The First Gun 11. The Bullet 12. The Sea-going Boat 13. The Cave 14. The Slab Found in the Cave 15. Old Coins Found in Cave 16. Cane Crusher 17. A Magnet 18. Magnetic Induction 19. The Two Magnets 20. Making a Permanent Magnet 21. Illustrating Wind Pressure, 1 22. Illustrating Wind Pressure, 2 23. Mariner's Compass 24. Chart of the Voyage 25. The Charting Board 26. Guava 27. Coffee 28. Cream Separator 29. The Lion and Cubs 30. The Puma 31. The Acajou THE MYSTERIES OF THE CAVERNS CHAPTER I MYSTERIOUS DISAPPEARANCE OF THE TEAM The boys looked at the Professor in amazement. They were too much excited and concerned at the new situation to be able to interpret what the sudden disappearance of their team meant. The Professor turned to the boys: "Are you sure the yaks were tied before we left them?" "I was particularly careful," answered Harry, "to tie both of them." "I am pretty sure that both were securely fastened, and they were in that condition when I came back the last time," was George's reply. To understand the peculiar situation above referred to, it will be necessary to go back and briefly relate some of the remarkable events which had taken place in the lives of the three people concerned in this history. George Mayfield and Harry Crandall, together with a Professor, were mates on a ship training school, which sailed from New York one year before. A terrific explosion at sea cast them adrift in mid-Pacific Ocean, and after five days of suffering they were cast ashore on an apparently uncharted island, without any food, and entirely devoid of any tools, implements or weapons. Exercising the knowledge of the Professor, and the ingenuity of the boys, they gradually dug from mother earth and from the rocks and trees the articles necessary to sustain life, and eventually they found different ores from which various implements and weapons were made. They constructed numerous machines, crude, at first, and gradually developed them. They succeeded in capturing yaks, a bovine species of animals, some of which were trained like oxen; wagons were built; a shop constructed; a water wheel installed; a primitive sawmill put up; a primary battery made; articles of clothing woven; felt made; and numerous things of this character originated from material which nature had furnished in its crude state. While doing all this the desire to explore the island was a predominating one. Four trips into the interior had been made in order to ascertain whether or not it contained any human beings. During those trips numerous evidences were found to show that savages were there, and some indications that civilized people had visited the island. The peculiar happenings which excited their interest were the mysterious things that occurred at various times, among which the following may be briefly enumerated: The disappearance of a boat, which they built, and which was left at the place where the team was lost; the subsequent finding of the boat among debris on the seashore, having oars and rope in it which were strange to them; the removal of the flagpole and flag which had been erected up on a high point near the ocean, called Observation Hill, and the fire in the forest. To the foregoing may be added the discovery of a prospecting hole, which had been dug, evidently, by some one in the hope of finding mineral; a yak with a brand on it; wreckage of a boat, which, undoubtedly, belonged to their ill-fated ship; a gruesome skeleton on the seashore; and finally one of the lifeboats of the schoolship and a companion to their own, found on the shore of the stream where they now were. All these things were sufficient not only to cause alarm, but the greatest consternation on the part of the boys. It must be said, however, that the trials of the boys, under the calm, calculating deportment of the Professor, had done much to make them self-reliant. George, the elder, was of an exceedingly inquisitive turn of mind; he was a theorist, and tried to find out the reason for everything. On the other hand, Harry was practical in all his efforts; he could take the knowledge obtained and profit by it, as the previous volumes show. It was fortunate, therefore, as the Professor put it, that theory and practice were personified in the two boys, who, although companionable, were the exact opposites as types. The Professor never showed a preference, in any manner, for either. Like the true philosopher he saw the value of the two distinct qualities, the one useless without the other. When they had fully recovered from their astonishment, George was the first to speak. "They may have broken the fastenings." The Professor, who had been intently examining the tree to which they were hitched, said: "I can find no evidence of any undue wrench which might show that they had gotten away by their own exertions. Let us see whether we can follow the trail." The ground was covered with leaves, so that no earth was visible, and the only sort of trail left in a forest, under those conditions, is the slightly depressed tracks which the wheels make. They examined this, noting also the overturned leaves, which are usually left in the wake of cattle. The latter means seemed to be the only available way in which any trace could be made out, and this they followed. It led directly to the west, and toward the section they were desirous of exploring at the time the present trip was inaugurated. "How fast do you suppose the team is traveling?" "Certainly not faster than we are now going. They cannot be hurried very well, as you know, and we should be able to overtake them within an hour or two." "But what shall we do if we find them in charge of somebody?" That suggestion brought up at once a very serious question. They had made six pistols, very crude, it is true, but which served admirably as weapons of defense; but the hazardous part of the present situation was that only the Professor had one of the pistols, the others having been left with the team. The only thing which added some comfort was the knowledge that as the pistols required a special hook to enable them to cock the firing plug, and as the Professor had this hook, those who took the team might not be able to use the weapons against them. At this place it might be well to refer to Red Angel. Nearly nine months before, on one of their trips, a baby orang- outan had been captured, and the boys educated him, as best they could, and he really developed many reasonable instincts. It was Red Angel who left the wagon and followed them down the river, and who by his peculiar actions attracted attention to their missing team. "We owe something to Angel for his cuteness in coming for us," said Harry. The orang progressed rapidly, swinging, as he did, from tree to tree on the route, and when no trees were in sight, would shamble along in a peculiar way, as it is difficult for them to walk erect. Their feet are not adapted to promote a graceful gait. "The track seems to be lost," said the Professor. "I cannot make it out, either from the leaves or the depression. However, it appears best to follow this course." Without stopping they proceeded in the same general direction. Red Angel, who up to this time had followed the route taken by the party, now turned to the right, and when George called, refused to return. As George walked toward him, he kept advancing to the right, and could not be induced to come back. "Probably we should follow him," was the Professor's conclusion. It was evident from Angel's antics that the change in the course delighted him. George, who was ahead, soon stopped, and shouted back, gleefully. "Here are the tracks! Good fellow, come here!" Angel understood this. He had actually sensed the direction taken by the missing team, for here were the tracks. The only thing that grieved George was the absence of the honey pot. Angel's weakness was honey, and that was now with the team. Suddenly Angel, who was now in one of the large trees which grew all along the course, began an excitable chatter, and vigorously jumped from one limb to the next, and George, who knew his antics pretty well by this time, stopped and prepared himself for some new and unexpected development in this remarkable journey. Angel, on the other hand, started off through the trees with wonderful agility, and it was all the boys could do to follow. There, ahead of them, was the wagon perched against a tree, one of the front wheels and an axle broken, and the tongue wrenched off; but the yaks had disappeared. It is singular that the team had gone thus far without meeting an obstruction. As it was, one wheel had locked with a tree, and the yaks, by their tremendous power, had broken the parts mentioned and gone on. Before the wagon was reached, however, numbers of articles were found scattered along the trail, which were gathered up. The finding of the wagon was an intense relief. Their minds had been perturbed with this occurrence, as never before, and they had met numerous thrilling episodes before. "Something must have frightened the yaks, and they were going at a much greater speed than at a walk when they collided with the tree," observed the Professor. "Why do you think so?" asked Harry. "In the first place, the fact that our articles were scattered along the path before they reached the tree; and, secondly, the wagon pole and the wheel were strong enough to hold the yaks against the tree if they had been moving along at their usual gait." "Well, I am thankful that we have the wagon, even though the yaks are gone," said George, as he crawled into it. He peered out and continued in a surprised tone: "Where do you suppose the pistols are? Did you leave yours in the box, Harry?" "Yes; on the right side. Yours were there at the time. I saw all of them." "They are not here now, and it is likely they have been lost with some of the other things." Harry was up in an instant. "Where is the ammunition?" "It was all in the bottom of the box." It did not seem at all likely that the pistols or the ammunition could fall out of the box. It is true other things had fallen along the way, but this seemed to be such an unlikely occurrence that they could scarcely credit it. The provisions were safe, and you may be sure that Angel was not only petted, but he received a good share of the delicious sweet. It was now nearing night, and they were fully ten miles from home. Ten miles is not a long tramp, but to travelers like ours, already weary with their trudging and with the excitements of the day, it was concluded to camp in the wagon for the night, and then proceed home early in the morning. To take the wagon would be an impossibility. They really learned to love the patient yaks. For fully five months they had been daily companions, and were now so well trained that some discouragement was felt at being compelled again to break in others. They had an ample supply of good material in the herd to pick from, but it took time and patience to develop such a team as had been lost. During the entire night one of the trio kept watch, not so much from a feeling of fear as in the hope the yaks would return during the night; but they were doomed to disappointment. Morning came, but the yaks did not, and after gathering together the most useful belongings, and putting them into convenient bundles for carrying purposes, set out for home. The first question taken up by the boys after their return was the selection of a pair of young steers for the new team; and the work of making a new pair of yokes was carried forward with energy. They were in the midst of the planting season which had been interrupted when the last journey was undertaken. Hitherto it had been the custom to devote at least one day each week to hunting, on which occasions they also made trips to such points in the island as had not been previously visited; and it was also a part of their duty to examine the woods and the fields to find new specimens of plants, fruits and flowers; and among the hills and ravines were many kinds of ore, some of which they had been fortunate enough to find on their entry to the island. The metals thus found were utilized, because they had set up a workshop alongside the sawmill, and in it had a crude lathe adapted to work in wood or iron. It will thus be seen that each tour was for prospecting purposes, to supply their needs, as well as to learn what the island contained. Each evening it was the habit to have a general discussion concerning the events of the day, or with reference to matters of moment about the work to be done on the morrow. George was much interested in the planting program. "What kinds of vegetable would it be most advisable to plant in the space we have prepared?" "One of the important points to consider in the planting of all crops is whether the soil is adapted for it. When the United States were first settled it was a surprising thing that many of the original settlers would go miles inland, exposed to every sort of danger, to find land, when there was plenty nearer the seashore or close to civilization. There was a reason for that which we are only now beginning fully to understand. Plants have a habit of growing in soil adapted for their needs, and it would be an interesting study in going over our island to consider the habits of plants in this respect." "Is that the reason why different countries have such different kinds of plants?" "Yes; plants select their soil, and owing to these habits, every variety of soil, in every climate, supports its own vegetable tribes. Of the five thousand flowering plants of central Europe, only three hundred grow on peaty soils, and those are mainly rushes and sedges. In the native forests of northern Europe and America, the unlettered explorer hails with joy the broad-leaved trees glittering in the sun among the pines, as a symptom of good land, which he knows how to cultivate. The rudest peasant in Europe knows that wheat and beans seek clay soils; the northern German knows that rye alone and the potato are best adapted for the blowing sands of that country; the Chinese peasant, that the warm sloping banks of light land are fitted for the tea plant, and stiff, wet, impervious flooded clays for his rice. Even the slaves in the Southern States were aware that open alluvial lands were best suited to cotton; and the degraded slaves of Pernambuco know that the cocoa grows only on the sandy soils of the coast, just the same as in west Africa the oil palms flourish on the moist sea sand that skirts the shore, and the mangroves where muddy shallows are daily deserted by the retiring tide." "Some time ago you stated in one of our talks that soil was the necessary thing to select in order to propagate, or make good fruit and grain out of the poor or wild kind. Were all our vegetables and grains originally wild?" "Originally nothing in the way of fruit, flower, grain or garden vegetables was anything but wild and unproductive, or bitter, tasteless or unprofitable. Chemical changes are made in the plant by the soil in which it grows, because it is from the soil that it gets its food. The large and juicy carrot found at home is nothing but the woody spindle of the wild carrot, and I have found several species of it here. Cabbages, cauliflowers, Brussels sprouts and a host of other like vegetables were, in their natural state, poor, woody, bitter stems, and had useless roots. As I have already stated, the wild potato, which we are now cultivating, has, in its original state, a bitter root, as you have discovered." CHAPTER II WORKING ON THE NEW BOAT Early the following morning Harry sprang out of bed and hurriedly shouted: "What did we do with the lifeboat in South River? Do you remember whether we secured it when Angel came up and let us know about the team?" The Professor and George were up in an instant. George was the first to answer. "I left it the moment Angel came up." "I cannot remember," said the Professor, slowly, "but it seems to me, now that I think of it, we left it on the banks, and it wouldn't do to leave it there. You must go for it at once, and bring it down to the bay, even though you cannot bring it around the cliffs." A hurried breakfast was prepared and the boys started off at an eager pace for the river. They went directly southwest, aiming to strike the river near the falls, and after passing over familiar ground, came within several miles of it, when, in going down one of the sloping descents, saw, in the distance, what appeared to be portion of the yoke which the yaks carried. They hurried forward, and great was the delight at finding it was really one of those they had made and used for months. It was a gratification to know that the animals were east of the falls, and, probably, sooner or later, would turn up at their home. Only one of the yokes was found, but there was evidence that both of the yaks were freed, since the part of the other yoke was still attached to the part found. The boys were glad of this, as they had such a friendly feeling for the animals that they could not but feel that to be yoked together in the forest would be a cruelty to them. "The Professor will be glad to know this," said George. "Look at this part of the yoke, where it has been broken. I have no doubt that this is where they struck the tree where the wagon caught." Fig. 1. The Broken Yoke "Let us take it with us, by all means," said Harry. An examination of the yoke plainly showed where it had come in contact with bark with considerable force. "What do you suppose caused them to be so frightened as to run away?" They quickened their steps, and soon reached the river. There, on the shore, was the lifeboat, as they had left it, and it was the work of minutes only to set it adrift, and after depositing the yoke in the bottom, the first task was to supply themselves with a pair of oars. The first article turned out in the way of tools was a bolo, a heavy cleaver-like blade, used by many primitive tribes. This article was duplicated by them, and always carried on all their expeditions. With this several small trees were cut down, and a pair of oars fashioned for each, and within an hour they were on their way down the stream, and in two hours more had rounded the point of projecting land east of the river mouth. "Don't let us take any more chances of losing this boat. I am in favor of taking it around, and am willing to risk the tide, whatever it may be." Harry's suggestion met with favor on the part of George, and when the point was rounded and they were out in the ocean, the tide, although coming in, had no terrors for them, but they boldly plied the oars, and before four o'clock had rounded the cliff point, and steered the craft into the mouth of Cataract River. The Cataract was a much smaller stream than South River, and it was on the northern side of the island; whereas South River was on the southerly side of the island. Less than a quarter of a mile from the open sea was a cataract, at which their home was located, and the cataract was utilized as the means for producing water power. Their appearance below the Cataract was hailed with delight by the Professor, and you may be sure that when the boat was finally landed and hauled up on the beach, all of them joined in the congratulations, which was their due. "Just to think of it. If we had the boat we made, our lifeboat and all the parts of the wreck of the other boat, we would have a pretty respectable navy," was Harry's observation, when they landed. As it was, they now had the wrecked after part of their own lifeboat, and here was the other lying alongside. They knew the history of one of them. Would they soon know why the other should have been found in the interior of the island under such peculiar circumstances? "And where did you get the yoke?" asked the Professor, as his eye caught sight of it. "Two miles this side of the falls." They little knew at this time what an important bearing the finding of this boat would have on their future course, nor could they know how this little incident would be of the greatest value to some of their companions on the ill-fated ship. They now had possession of a boat which, while it was practically unsinkable, was not of such size as to meet their demands for the intended explorations. They felt that to attempt to circumnavigate the island and take all the chances which a meeting with natives might involve, would necessitate a much larger vessel. To add to the difficulty, all the pistols but one had been lost in the last trip, and to attempt to make explorations without proper weapons would be foolhardy. If they knew one thing, with any degree of certainty, it was that the island contained savages of some description, and provision must be made for every contingency. Harry took upon himself the task of turning out more of the weapons, and with the experience of the past four months in this line of work, concluded he would attempt a better job than simply making pistols. It was his ambition to make a firearm that would enable them to bag the largest game, and also, at the same time, carry the bullets a greater distance than the short eight-inch barrels could. To do this it was necessary to provide longer bits, and as the design of the new guns contemplated a barrel at least eighteen inches long, the bits had to be longer, in proportion, and the making of these consumed nearly as much time as the actual drilling out of the barrels. George and the Professor put in a great deal of time with the new team. Their knowledge of training, in view of the former experience with these animals, was such that within a week they could drive the yaks without much difficulty, although the new team was not by any manner of means as efficient as the lost one. When the question of the kind of material for the guns came up, Harry was much concerned, as in making the barrels that length would necessarily greatly increase the weight. "I think it would be better to make an alloy for your purposes," said the Professor, as they were discussing the matter. "What is an alloy?" "It is the combination of two or more metals." "In what way does the alloy make it better than the hardest steel?" "It is not hardness you want, but toughness. Metals have several properties, which are utilized for various purposes in the arts. Surprising as it may seem, wood has greater resisting power than diamond, and yet the precious stone is the hardest of all substances." "But if we unite two metals are we not then making a new metal?" "Not necessarily so. In the case of brass it is true. This is made by uniting two parts of copper and one of zinc. Both copper and zinc in themselves are very soft, and copper cannot well be polished in its pure state. Brass, however, is not only much harder, but is susceptible of a very fine polish." "Are the alloys of all metals harder than the metals of which they are made?" "This seems to be a universal law in the compounding of metals. Very few metals are used alone in the various arts and manufactures. For every purpose some combination has been found which makes the product better. Even coins are so alloyed. Silver and gold in the form of money would be entirely too soft, unless alloyed with some hardening metal. Some substances, like arsenic, antimony and bismuth, are too brittle to be used alone. The only metals which can be used alone are aluminum, zinc, iron, tin, copper, lead, mercury, silver, gold and platinum." "What is bronze, of which all the ancient guns were made?" "That is a combination of copper and tin. This product was known fully seven hundred years before the Christian era, and was used in the making of guns until superseded by the various steel alloys of our day." "In what proportions are copper and tin united to make bronze?" "The proportions vary greatly. Ancient Celtic bronze had 12 parts tin and 88 of copper; Egyptian, 22 tin, 78 copper; Chinese, 20 tin, 80 copper; Roman, 15 tin, 85 copper; and in many specimens lead and zinc were also used. Tin has a capacity to harden almost any metal." "What is the best metal to harden steel?" "Manganese, of which you will remember we have some samples; it is the most serviceable, as we have neither nickel nor chromium." "What amount of that metal should we use to get the best results?" "About 14 per cent. of manganese has been found the best for such purposes as would be required in gun barrels. There is a curious thing which has been discovered in uniting manganese with steel. It becomes fairly tough if 1 per cent. is used with the steel; if the quantity added is between 1-1/4 and 3-1/2 the strength and ductility decrease; but above that, up to 5 per cent., the steel becomes brittle; above 6-1/2 per cent. it again returns to ductility and toughness and its maximum strength is found at 14 per cent." During the evenings all took a hand at cutting out the stocks for the guns, and the plans upon which they were constructed will be fully explained and illustrated in the order of the work done. Meanwhile it must not be supposed that work on the new boat had ceased. Harry's plan, when fully worked out, provided for one twenty feet long and six and a half feet wide amidships. The drawing (Fig. 2) shows the construction of the hull. As they had no means for doing any fancy bending of the boards, the bottom was made flat, and the sides sloping. The bottom and the sides were made in the following manner: Two stringers (A, A) were first constructed, which were made up of thin pieces nailed together, so they could be bent in the proper shape for the bottom boards, which were laid crosswise and nailed to these stringers. Fig 2-3. Working on the new boat For the upper edges of the sides, called the gunwale (B, B), similar stringers were provided, but they extended farther fore and aft, and amidships were fully six and a half feet apart, whereas the lower stringers amidships were four and a half feet apart. This arrangement, therefore, provided for sloping sides, and the side pieces ran up and down on the inner course. It will be understood that the sides and bottom thus formed were to be overlaid with thin boards running fore and aft, as in Fig. 2, as they had no means for matching the boards and thus putting them together tightly. The sides were two and a half feet high. Six and a half feet from the forward end was a cross beam (C), into which the mast was to be stepped. At the stern the bottom was sloping upwardly at an angle and brackets (D) were extended back and joined at their rear ends, to which the lower end of the rudder post was attached. Amidships a keel (E) was formed, projecting down from the bottom, this keel being, at its widest part, two feet, and tapering down to merge with the bottom, fore and aft. The cross section (Fig. 4) shows how well he had formed the vessel, proportionally. Fig. 4. Cross Section. In addition to the cross seats, similar arrangements for comfort were made along the sides, and beneath the side seats were spaces in which their supplies were to be placed. The space forward of the mast was entirely closed over with a roof which sloped in both directions, and here provision was made for two berths. This would also afford them protection and serve as a means to keep out the water and insure at least one dry spot for their comfort. As usual, George had some inquiries to make about the boat. "It has always been a matter of wonder why all boats are made with the big bulging part nearest the forward end?" The Professor's eyes twinkled. "Probably there are a great many others who have had such thoughts. There is really no reason for it. It is not known how the custom originated, except that in sailing vessels the claim is that the ship can be maneuvered more easily by such construction." "In what way does it make it easier to handle?" "When a ship is driven forward by the wind, all the force exerted on the sails is transferred to the forward part of the ship, hence if made narrow at its forward end it would be driven down into the water, and the hull would, therefore, be submerged more at the forward than at the rear end. Furthermore, by having a tapering rear end, the rudder has a better opportunity of veering the ship around and you can see that the bulging part, being located forward of the middle portion of the ship, acts as a sort of pivot." "But it seems to me that none of the reasons given will apply to a steamship, and still all the ships I have seen are made in the same way as the sailing vessels." "That is exactly what I inferred in my answer to your first question. The truth is, that in experiments which have been made, it is shown that to have the widest part of a steamer near the stern, gives lines to a hull which has less resistance than if made in the conventional way." "I thought probably the reason for making them so was just the same as in the case of an arrow, where the heaviest part is at the forward end." "In that case an entirely different principle is involved. A body falls, or is projected through the air, with its heaviest end foremost, because of the greater momentum in that portion." "It is the force of a body in motion. When a body is projected through the air it meets with the resistance of the atmosphere, and this also serves to turn the heavy side around to the forward end, because the force of momentum in the heavy end is much less affected by the resistance of the air than the lighter end." (See Fig. 5.) Fig. 5. Fig. 6. Red Angel. Red Angel had now been with them more than six months, and he was probably a year old. When first captured he was a scrawny infant, dull and stupid, like all of his class. He had wonderful powers in the way of imitating habits and customs. The boys were very good vocalists, and while at work Harry would sing, but George whistled. It was an amusing sight to watch Red Angel when the boys engaged in the frequent concerts at night. But of all the screamingly funny exhibitions, the attempt of Angel to imitate whistling was the most ludicrous. The orang's lips project too much to a point, and the jaws are so narrowed that the lips will not pucker. Whenever the boys commenced their concert Angel would be on hand, and enjoyed every moment of the time, and the boys had many a concert purely for his benefit. At the end of each concert the whistling would begin. This invariably brought Angel to the front, and his exhibitions would be given with the utmost gravity and earnestness. The invariable result would be such uproarious fits of laughter on the part of all that he would take part in the jollification, little suspecting that the laughter was at his expense. The only sound which he could emit during these performances sounded like a high-pitched stick rattling along a pale fence; but he was inordinately proud of it. It had always been on one key, heretofore, and without variation; but this evening Angel startled himself, as he did the others, by actually sounding two additional notes. He repeated this over and over. "I wonder if we could make him talk?" asked George, after the laughter had subsided. "There is no reason why some tones cannot be imitated. As the orang possesses wonderful powers of imitation and has, in captivity, developed many traits, I see no reason why simple words, or sounds, cannot be taught." "I know there are words which he does understand. Time and again I have told him things, which he seems to understand. Now see if he understands this: 'Angel, do you want some honey?'" His attempts at whistling ceased, and in a moment more was in the kitchen. Harry, who by this time had recovered from his mirth, thought it would be a good idea to attempt to teach him. "If canary birds and dogs can understand language, I do not see why Angel shouldn't." "Unquestionably, any animal, by patience, will learn the meaning of sounds. Constant repetition of certain notes causes birds to repeat them. I have known dogs to perform almost anything they were told to do, although they are not able to utter a single sound of the words emitted in giving the command." "Well, what is it that causes sound?" "The most wonderful thing in nature is, that she manifests herself in only one way, namely, by a movement, or a motion of some kind. Vibration is the term used to designate this. Sound, light, heat, taste, smell, and everything which becomes sensible to us is produced by vibration. The movements of the heavenly bodies, swinging back and forth around the sun, like huge pendulums, the movement of the sap in trees, up and down, the beating of the heart, the winking eyelids are all motions which show energy, development, life." "But what is it that makes us understand one sound from the others?" "Simply the difference in the kind of vibration. There are three things which characterize sounds; namely, pitch, intensity and character. Pitch depends on the rapidity of the vibrations; intensity on the extent or the amplitude of the vibrations; and character on the substance or instrument producing them. To illustrate: When you sing a very high note the vibrations may be five thousand vibrations a second, or there may be only two thousand during that time. That represents the pitch. In singing that note you may sing it so loud that, like a pendulum, it will swing way over to one side, or it may move only a short distance. That represents intensity. If either you or George had sung that note I should have been able to detect it, whatever its pitch or intensity, because your voices are as unlike as different musical instruments, and that is character, or timbre, as the French call it." CHAPTER III THE HIDDEN MESSAGE While the work of getting out the planking for the boat was going on, and the plowing had now been resumed, since the new yoke of oxen were fitted to do the work, the boys were not forgetful of the usual weekly outing. They had several quite important things right at home which needed looking into, if they wanted to solve some of the things on the island. First, the cave, which they had twice attempted to explore; the search for their lost boat, which had the strange rope and oars; and the mystery of the flag and pole. These things weighed heavily on their minds, because these happenings were close at hand. But what made the greatest impression on the minds of all was the finding of the Investigator's lifeboat. It seemed almost like a call to them from the interior. The impatience of the boys was almost beyond restraint, at times. "It does seem to me that we should not delay an hour in making some effort to explore the direction the boat came from," was George's view of the situation as they canvassed the subject. "That is my idea, also, and I am not in favor of giving much more time to hunting or other forms of recreation until we know how that boat came to South River." "Yes; I can appreciate how anxious you are," said the Professor, after the boys had given their views. "What we are doing, however, is essential from every point of view. We must prepare provisions, so that we shall be able to know where we can get them in case of need. On the other hand, weapons are necessary, which take time to construct. If, however, it is thought advisable, we might make a trip of explorations along the South River, beyond the falls, the time to be limited to a week; but I have my doubts of the wisdom of such a course." This suggestion appealed strongly to the boys, who were always keen for anything which savored of adventure, and it was some time before the boys could reconcile themselves to the saner an...