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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.