The sail was completed, and taken down to be bent on the cable. The jib had already been installed in place, and when the sails were hoisted and they walked out from the shore and glanced back to get a full view, the entire Naval Bureau congratulated itself on the magnificent appearance of the fleet, and particularly of the new creation in maritime architecture.

It is not out of place to say that the Professor and George both showered the highest compliments on Harry, for he deserved it. But the officials of the establishment were not the only ones to admire the fine sight. Angel came, and he took it in. It was the finest climbing he had enjoyed in many a day. The Professor took off his hat. "I propose three cheers for our ship."

They were given, and with each cheer the hats circled their heads. This was a new code of procedure to Angel. He couldn't understand it. Without waiting for explanations, he shot down the mast, and landed on shore. It was the most comical proceeding they had ever witnessed on his part, and when he looked at the group, and then at the ship, he said as plainly as though he had uttered it: "What does all this mean?"

When the laughter was over, George proposed three cheers for Angel. The hats came off and the cheers were given. Then the same smile which he had so well learned illuminated his projecting face, and he swung his long arm around as he had seen it done, and another step had been taken in his education.



CHAPTER VI

THE GRUESOME FINDS IN THE CAVE

Another week had thus passed by—seven days of unceasing toil. The Professor again brought up the subject of the cave. The subject did not need any argument. It fell on willing ears.

"How shall we take the boat around?" was the matter which interested George.

"Sail it around, of course," was Harry's view.

Both looked at the Professor. "If we sail it there, which will be an easy matter, how can we haul it up the sides of the cliffs? From my present recollection the mouth of the cave is fully thirty feet or more from the water line. The air pocket is not over eight or ten feet. At any rate, it is much lower."

"Then why not haul it around on the wagon, and lower it down the walls?"

"That seems the most feasible plan."

They now knew what preparations were needed for the exploration. Two lamps had been taken before, and one was lost in the cave. Since that several more had been made, so that three were provided, together with a supply of matches.

When the wagon was ready the Professor brought out several boards, and deposited them in the wagon. The boys looked at the boards inquiringly, as the Professor turned back from the wagon. "Oh, yes, the boards; we want something to write on so that we can chart the cave. We must not be caught as we were the last time."

"But how can we possibly chart the cave when we have only one boat?" And George laughed at the idea of making a plan of the interior by standing at one point.

"You measured the height of the falls without going to the top, if you will remember."

He had forgotten that. But the boat was at last secured in the wagon, and proceeded to the cliffs. It was fortunate that the team could be taken to a point directly over the mouth of the cave, and in a little while the ropes were attached to it and slowly lowered, Harry taking the precaution to follow it down and to dislodge it from the steps which appeared in its path.

The team was then securely hitched, and taking all their implements, such as lamps and boards, together with two of the guns and an ample supply of ammunition, descended to the entrance. The boat was at the mouth, and it was suggested that a preliminary survey of the interior should first be made, in order to ascertain how far the boat would have to be carried before reaching the water.

The lamps were lighted, and the boys led the way. After passing the point, about two hundred feet from the mouth, and at almost the identical spot where the water was found at the first exploration, the water glistened before them. Returning toward the opening a loud beating sound was heard, which at first startled them. It was evidently at the mouth of the cave. It sounded like the beating of a stick against some hard substance.

The nearer they came to daylight, the more distinct were the sounds. As heretofore explained, near the entrance the cave made a turn to the right at an angle, so that when at a distance of fifty feet from the opening it was impossible to see daylight, except what little was diffracted from the angle at the turn.

This angle was reached, and the beating, rather irregular, was plain enough to cause some alarm. The boat was beyond the open mouth and at one side, so that it could not be seen by anyone within the recessed walls.

All stood still, while the beatings continued. Occasionally there would be a cessation, to be repeated again. Whatever it was it was not far away. The Professor whispered: "Get the guns ready; we must take some chances."

Cautiously the company moved forward; the end of the boat first appeared in sight, and as George peered beyond the projecting point of the ledge, he threw up his hands and burst out in laughter. Angel was in the boat, imitating Harry in the building operation. The sudden appearance did not startle him in the least, nor did he stop beating his lullaby, after he noticed the broad smiles that greeted him.

With an eye to every advantage, Harry had attached to the sides of the boat, amidships, two short standards, about three feet high, on top of which two of the lamps were mounted, so they would be out of the way, and thus give them freedom to handle the oars and the weapons, as well as afford them a better light, than if carried by hand. The Professor was much pleased with this arrangement.

The boat was not particularly heavy, but it was a task to drag it over the uneven floor and along the tortuous path which had to be taken by their burden, but when the water was reached they were repaid for the labor by the ease with which they could explore the interior.

Before starting the journey the Professor, as usual, uttered a few words of advice: "One of us must sit in the bow, one at the stern, and the other amidships. The one at the stern must propel the boat, as we cannot row through many of the places, and as the water is not deep, that will not be a difficult task. The ones at the bow and amidships should have the guns, and if there is no objection, I will take my place on the middle seat, where I can best take the observations on the way. The other places you should decide between yourselves."

"I am willing to take the bow, if Harry agrees." Harry sanctioned the arrangement, and when the lamps were securely fastened, Harry pushed the boat forward through the cavern. It did not take long to reach the slight turn which led to the large chamber, which was over one hundred feet long.

On the way to the chamber Harry had an opportunity to measure the depths of the water, and at intervals the Professor would call out for the depths, as he was making notes of the descent formed by the floor to the chamber. The oars gave a pretty fair idea, showing that the floor was only about five feet lower at the chamber than where the boat was launched.

Reaching the chamber Harry was directed to steer it to the right and skirt the wall going to the left, so that every part of it could be examined.



"I have another reason for this careful examination," remarked the Professor, as he was intently engaged in making notes on the board tablets. "It may be likely that the chamber has more than one outlet and if so, we must explore it also. Of course, I am most interested in the outlet to the south."

A circuit was made until they reached the outlet to the south, which Harry had discovered when the light on the ledge disappeared. The water throughout the cavern within the chamber was not over eight feet deep, and at the outlet to the south he could not touch bottom with the twelve-foot pole they carried. This outlet was contracted, and, judging from the width of the boat, could not be more than eight feet across, but it gradually widened, and the waters became shallower as they advanced.

George, who was in the bow, held up his hand as a warning. "Stop!" was all he said. All peered forward. The lights threw their beams forwardly through a broadening channel, beyond which appeared to be white forms ranged along the opposite wall.

"What depth have you, Harry?" asked the Professor, without seeming at all concerned.

"About five feet."

"Move straight ahead, until I tell you to stop."

The pole was thrust down and the boat moved forwardly fully fifty feet before a halt was called.

"I think we are now in the middle of this chamber. Before exploring it let us make a thorough examination of its characteristics."

"Look at those wonderful icicles hanging from the roof!" George gazed on them with wonder and admiration. Harry, on the other hand, with the utilitarian idea in his mind, inquired: "Why couldn't all that chalk be utilized for making plaster?"

"That product is used in the arts, but it costs too much to transport it from the places where it is found in its natural state, as science has found a much cheaper way of producing it from limestone."

"Are all these rocks limestone?"

"Beyond question. Only a few of the caves so far found are in any other formation than limestone."

"What kind of cave are those?"

"Where they have been produced by volcanic action. There the walls are of volcanic rock."

"Why is it that these underground channels are formed in this way?"

"They are formed by the erosive action of the water wearing out the softer portions of the rock beneath a harder roof or wall. This action is brought about by carbonic acid acting on the rock and producing what is called carbonate of lime, and the stalactites and stalagmites found in all these caverns are of that material."

"What is the difference between the two names you have just mentioned?"

"Stalactite means trickling or dropping, and as applied to these formations it means conical or cylindrical accretions of the carbonate. Stalagmite is the term used to designate the calcareous formations found on the floors of caverns, which are usually the droppings from the roof."

"Where are most of the caves found?"

"They occur most frequently along rocky shores of open seas, as in this case. Some of them are celebrated for their great extent, others for their gorgeous interiors, like this chamber. Some show the most beautiful draperies, or veils; in some cases portions of the ceiling have representations of magnificent inverted candelabra, and what appear to be carvings in the purest white."

"In what parts of the world are most of them found?"

"It does not seem that any portion of the world has a monopoly. The most celebrated are the grotto of Antiparas, in Greece; the Adelsberg caverns in Carniola, and the Mammoth in Kentucky. The latter is the largest in the world, the windings of which extend forty miles and through which is a subterranean river. In the river are eyeless fish, and fish with eyes, but sightless. Others are the Luray, in Virginia; the Wyandotte, in Indiana; Weir's, in Virginia; the Big Saltpeter, in Missouri, and Ball's, in New York. Of seashore caverns, the most famous and remarkable is Fingal's, on the coast of Scotland. Extensive caves are also found in the Azores, Canary Islands, in Iceland, in various portions of England, France and Belgium. Many of them are of immense value to the paleontologist."

"In what way are they of any use?"

"They have been of the greatest service, because in the early days of man, and before he knew enough to build his own habitation, he made the cave his home. You have heard of the 'cave man,' have you not? During the old stone period in England and other European countries, these caverns were the only abodes of man, and in them have been found layers from twenty to thirty feet thick, of successive accretions of bone, stalagmites and various articles of human manufacture."

This information added interest to the examination of the walls, and the eagerness of the boys to discover something new and startling was at its keenest edge. Before they had made a half circuit George announced that he could see a large opening, which turned to the right, and thus formed a bend to the general direction that the cavern had made.

A digression is necessary, in order to be able to understand all the elements in this remarkable voyage. The mouth of the cave was northeast of the Cataract home, and distant about a half mile, in a straight line. The opening for the first six hundred feet, which had been charted by them on the previous occasion, ran directly south, but from that point it turned toward the southwest, and this now, in a measure, explained the eagerness of the Professor to explore it, as he believed the cavern led to a point near their home.

"There is no water in the opening," was the further information from George, as they approached the contracted end of the chamber.

"Before we land let us see the other side of the chamber," was the Professor's suggestion.

The boat was veered around to the left, and before they had proceeded fifty feet it was apparent that a similar opening led out to the south, and a dry floor was visible, like in the other outlet. The boat was landed, and drawn up, two of the lamps taken out and the guns examined. The opening led into a second chamber, which looked like a canopied grotto of marble. Where they stood the chamber had the appearance of a huge letter A, the side walls of which ran together in the distance, but these walls were broken up by the most enchanting series of columns, and delicate entablatures, and the outlines of the figures were like blanched frescoes. It was such a weird and startling sight that the boys could not repress their amazement.

After they had fully entered the chamber Harry's quick eye caught a peculiar formation to the right, on a raised sort of platform, behind which seemed to be a recess. He had noticed it because it contrasted so strangely with the uniformly white glare of all the surrounding surfaces. He quickly made his way across, and as he reached it, stepped back in alarm.

"Come here, quickly; are those skulls and skeletons?"

The Professor did not need a second invitation. Scattered about on the elevation were found four skulls, and the bones comprising the remains of four human beings. The skulls were first arranged side by side, and the Professor intently examined them.

"These are skulls of the Caucasian race, beyond a doubt. All are, apparently, well formed and normal. But what is this?"

In the side of one skull was a perforation, with the bone fractured on all sides of the orifice.

"Do you think it is a bullet wound?"

"It has that appearance. As there seems to be no corresponding hole in any other portion of the skull, we may be able to find the missile inside, if death was caused by that means."

Harry had noticed a rattling sound when the skull was put in place, and mentioned this. After some hesitation the course of the fractured opening was traced through, and embedded near the top and on the opposite side, was a large lead ball, or what had been, undoubtedly, spherically shaped before it entered and passed through the bones.

"This is evidence to me that these remains have been here a long time."

"Why; because it is in the form of a ball, and not a bullet?"

"Yes; and there is also another reason why these people came here and met their fate many, many years ago."

"What is that?"

"In this calcareous formation the preservative qualities of the carbonates would prevent rapid decomposition. These skulls are turning to the same material that we see all about us. See how brittle the bones are. Our bones are of lime formation, being largely composed of the carbonate, the same as the stalactites."

The other substances now lying about were noticed. The excitement engendered at the sight of the bones was enough temporarily to blind them to the numerous things found scattered about. Here was a dirk, the edges entirely worn away, and whitened. There were the metal ribs of what seemed to be a case, or a receptacle of some kind. Lying at one side was an ancient type of firearm, long, heavy, and with an immense bore. Another and another were found—a regular arsenal, with the scattered remnants of peculiar little copper receptacles with whitish powder in them.

Harry, who was about to remove the powder, was stopped by the Professor. "We must retain everything as we find it, as nearly as possible. We do not yet know what the little vessels contain."

Not an article of clothing thus far had been found. A little higher up on the platform, two more skeletons were seen, both of which had fractured skulls, one of them showing two cavities which could not have been accidental, as both showed the same kind of fracture, and inclined across the skull in the same direction on the left side.

Alongside these skeletons were more of the long, wicked-looking firearms which had been found previously near the other bodies. There was every evidence to show that a terrible fight had terminated the existence of the band. More long knives, with curiously wrought handles, were lying behind the last skeletons, and on a more careful examination, a knife of an entirely different pattern was found within the ribbed cavity of one of them.

Still farther back, new articles appeared. Articles of furniture, many of them coated with the fallen carbonates; and here were the first articles of clothing, some of which were so decomposed as to crumble at the touch. Others were still firm. Some of the articles, like a mantle, had threads intact running in one direction, and the other cross thread all converted into dust, which disappeared when the garment was held up.

On some of the garments were metal trimmings. "They look like silver," said George, excitedly; "and what is this? It seems to be silver," as he brushed a bracelet-like piece of ornamentation with the sleeve of his coat. As they advanced new articles came in sight; a bench; a veritable chair, or couch, the covering of which was there merely to give it form, but the substance had gone. Only the wood remained and that largely decayed.

And now on every side, at the rear and along the walls of the recess, were evidences of human habitation. Cutlasses, knives, and at one side, what appeared to be the kitchen, were numerous pots and kettles of various sizes and descriptions, nearly all of them of copper.

"How could they possibly cook in here without being smothered to death?" asked Harry.

"The cavern seems to be large enough to take care of all the smoke," was the Professor's reply.

"Well, I don't understand why they should have taken the trouble to come in such a long distance, when they would be just as safe nearer the mouth?"

"Before we leave this place we may be able to answer your two questions in a way that will surprise, if not startle, you," was the Professor's answer.

This vague reply did not detract any from the interest which the boys took in the search.



CHAPTER VII

THE TREASURES OF THE CAVE

While Harry was in the act of drawing back one of the couches, an object behind it seemed to fall apart with a jingling sound.

"What was that?" exclaimed George.

"I think we have found something here that will make us do some thinking," answered Harry, as he bent down to take up some of the detached pieces which came from what now appeared to be a large chest. He picked up one of the round pieces. "Gold, gold; look at it!"

"I suspected something of the kind when I saw the skeletons. Carefully, boys; let us remove this piece of furniture. Undoubtedly, we are in pirates' lair, and here is the booty."



The boys were too much overcome for words. They looked at the gold, and then at each other. George arose and walked back and forth. Harry, with the coin in his hand, brushed it and held it close to the light.

"With this we can buy anything we want," George finally uttered.

"Whom will you buy it from?" was Harry reply. The Professor only smiled. Of what use was money to them? George had forgotten that.

"Here is another one."

"Another what?"

"A chest, something like yours." The lid, with its mocking lock, opened easily, and there, coated with the universal carbonate, were a mass of coins, articles of ornament, rings, bracelets, and pieces the names or uses of which were entirely unknown to them.

"Now that we have them, what shall be done with the treasures?"

The boys did not answer for some time. Here was wealth; more, probably, than either had ever dreamed of; but it was of no earthly use to them. They must, of course, preserve it. They had discovered it, and under all the laws were entitled to possession.

"Well, have we gotten together all the gold and silver and precious stones? Just imagine us as buccaneers! Owners of an island we haven't conquered, and possessors of a fortune without working for it!" and the Professor laughed at the thought of it. The boys, too, laughed, but when they looked over at the ghastly skeletons, the joy was suddenly checked.

The Professor saw the reason. "Isn't this a sermon? You have become acquainted with it early in life; some learn it very late, and others never get the lesson. Riches; death! Possessors of every material thing that earth can give, and the grave beyond it! The unfortunates there had all this, but their skeletons have stood guard over it for a century or more."

The Professor still smiled, but the boys were very grave. It was, indeed, an impressive lesson.

"Why are you so quiet? Are you mourning for them?" Then, without waiting for more gloomy feelings, he continued: "How high above the mouth of the cave do you think we are?"

This sudden change in the tone of the Professor was almost startling to them. How indifferent! It appeared almost like desecration.

"I have no idea," was Harry's faltering reply. He looked around to assure himself that it was not all a dream. The sudden acquisition of what appeared to be an immense store of wealth, the ghastly relics below, seemed to stun him.

"Have you a reason for wanting to know how high up we are?" asked George when he had partially recovered.

"You wanted to know a little while ago how the smoke in the cavern might affect them. Haven't you noticed a perceptible movement in the atmosphere since we entered the chamber?"

The boys started and stared at him. Could it be that the cave had an outlet in the hills?

"Was that the reason you suggested we should make a circuit around the chamber after we entered it?"

"Yes; and I know where the outlet is."

"And does that explain why the pirates made their home at this end?"

"Undoubtedly; and what will be still more interesting information is, that the opening is within sight of the cataract."

Could anything be more exciting than this information?

"I now see the reason why you always wanted to come back to the cave. Did you suspect this when we first entered the cave?"

"No; but I had an idea we should find this after we made our second trip."

"What did you see?"

"Nothing but what Harry brought to me."

"What was that?" both exclaimed, eagerly.

"The slab of carbonate which Harry brought me for the marking tablet, and on which we made the chart of the cave."

"What did you find on it?"

"If you will recall, I brought it with me. It is now in the boat." Harry dashed down to the boat and brought it back, turning it over and over on the way.

The slab referred to was about two inches thick, a foot long, and probably ten inches wide, a little irregular in formation.

"When we returned home that evening, after the trip referred to, I took the slab and transferred the chart we had made to a board. In doing so, I noticed that the lime had been chipped away from one side, but that did not cause me to make any investigation at the time.

"Some days afterwards I again took it up, and could see plainly through the carbonate what appeared to be the shadows of some characters, and it at once occurred to me that, owing to the sunlight and the comparatively dry atmosphere in which it had been kept after its removal, that the lime would turn or change its color, but the lime on this background did not change in the same degree where the characters had been placed, and when we get into the sunlight you will be able to see just what I saw."

Looking at the slab, there was nothing to indicate any characters imprinted in it.

"Where is the opening, Professor?"

"Come here; directly below where we found the first skeleton; keep the light back in the recess; there; now look to the left and see that small streak of light about ten feet from the floor."

George could restrain himself no longer, but rushed forward. As he crossed a slightly elevated obstruction, his foot caught on a spur and he pitched forward. Harry, who was following, saw him fall. George, slightly stunned, had raised himself partly as Harry came up. When Harry saw him he was arising from a nest of bones which showed the remains of two more pirates, the two skulls lying close together, directly behind the little ridge over which George had fallen.

"Here are some more of them," cried Harry, as the Professor came up. "What a fight they must have had!"

The outlet at this point was fully eight feet wide, and without the lights it was still too dark to distinguish anything. George's light had been extinguished in the fall, but Harry's lamp was still available, and all were eager now to find the outlet. Harry now led the way, and within seventy-five feet, at a pronounced angle in the throat of the cave, he recognized the first real glimmer of sunlight.

"See the steps here!" was his cry. And beyond, as plainly formed as though cut a year ago, instead of a century, were steps leading up to a contracted opening, partly hidden by shrubbery.

When Harry emerged from the opening, the first sight that met his gaze, after he had fully recovered the use of his eyes, was their home, not a thousand feet away. George brushed his way out, and he stood there, not knowing whether to run or to shout or to cry. Every emotion appealed to the boys for mastery. All previous experiences during the past year paled into insignificance in comparison with the hour just spent in the pirates' lair.

The opening from which they left the cavern was on the side of a hill, not particularly steep, formed by projecting strata of limestone, in the clefts of which vegetation grew, and at a distance the rocks could be seen only at intervals on account of the shrubbery. No one could possibly suspect an opening into the walls anywhere along the hillside. The outlet was not more than twenty feet from the rather level ground, which sloped off toward the west and in the direction of Cataract River.

They sat there silently for a time, but evidently the Professor was not disposed to allow too much time for reflections which he knew must be gloomy to the boys' impressionable minds.

"What are you thinking about, boys? Have you had enough excitement for one day?"

George was the first to reply: "I have been thinking about what we ought to do with the gold."

"Why the gold? I have been thinking of the boat."

"Do you think we ought to leave the gold there? Isn't that of more importance than the boat?"

"I do not think so, George; we can use the boat to good advantage, but where can you utilize the gold?"

"But why would it not be a good idea to get it out and take it over to the Cataract?"

"I should advise against that very strongly."

"What are your reasons?"

"Suppose we should be attacked at the Cataract and find the home untenable; this place would be a safe retreat, and we should, in any event, have our treasure here in safety. It has been secure for the last century or so. I think it will keep for a few months more."

"It had never occurred to me that we could use this place for such a purpose. That is a capital idea. And did you have this in mind all along, Professor?"

"Yes."

After a time, when the subjects had been fully discussed, it was decided to try to bring the boat out by the new entrance, and after making all the measurements, ample room was found for this. They returned and carried and dragged it to the opening, and after some labor it was finally pushed through the opening, and when the ropes were attached it was lowered down the hillside, and dragged to a position where it could be taken by the team.

"You should go for the team now, and I will continue the explorations until you return," and so saying, the Professor went up the hill and entered the cave, leaving one of the lights at the opening.

The boys went back to the mouth of the cave and found the team, as well as Red Angel, who had remained there, and within a half hour were back again to the land entrance. The light was still where the Professor had placed it, and the boys at once entered the passageway, and went down the steps leading to the pirates' chamber.

All the bones of the skeletons had been removed from the passageway, where George had fallen, but the other skeletons were in the same place originally seen when they discovered the remains.

The Professor was not in sight, nor did they see any glimmer of his light.

It was he, undoubtedly, who had removed the bones from the passageway, but they did not stop to notice where they were deposited. When they first came in both were busy discussing the situation, in careless tones, without any pretense at suppressing their voices, but now that the Professor was not in sight, and no evidence that he was anywhere near, the scene about them began to be most weird and uncanny. They spoke in undertones, and when Harry suggested that they might call the Professor, and thus let him know of their return, it was some time before George would consent.

It became evident, as he did not appear, that something must be done, and Harry shouted loudly, and his voice reechoed through the cavern and came back to them from every quarter. In a few moments they were overjoyed to see the glimmer of a light directly to the east, which was in the opposite portion of the chamber, where, as his light moved forward, plainly showed another recess, or, probably, an opening similar to the one through which they had entered from the west side of the hill.

"Have you been waiting long?" was his inquiry.

"No; we came in less than ten minutes ago. Have you found anything new?"

"Nothing new, but many additional things; but we must take another day for this."

This was said so significantly that they looked at each other, debating in their minds whether or not the question should be pursued any further.

"Haven't you had enough for one day?" and he said this with such a jovial mien that it restored their composure and satisfied them that another day would bring the answer that they craved.

As they passed out George turned to the Professor and asked:

"Why did you remove the remains in the passageway?"

"Because I thought it might be well to examine them at our leisure, and therefore enable us, if possible, to learn something of their history. I have put them near the steps close to the entrance."

As they passed out he requested Harry to bring up the boards from the boat, as well as some ropes and part of the canvas, which was usually carried with them to be used as a means for signaling. The bones were arranged on the boards, and kept separate from each other; after which the canvas was severed and tied around the two human frames, to keep them in place, and deposited in the boat, after it had been loaded in the wagon.

It was now past two o'clock, and none of them felt any hunger until they neared home. The trip had occupied over four hours, and hungry as they were, the reaction, after the stirring events of the day, was so marked that it was difficult to rouse them sufficiently to prepare the meal.

Somehow, the work at the factory, the building of the boat, and the care of the stock did not interest them the following day. They went around like people in dreams. Their thoughts were centered in the cavern on the hill, and many, many times during the day their eyes involuntarily turned that way. Was it unnatural that such should be the case? When, if ever, in the history of human kind had such treasure been bestowed where the gift had been so lightly considered that they did not even stop long enough to count its value? It seemed such an unnatural thing to do, and yet the only feeling was one of curiosity.

During the entire day the boys rarely spoke to the Professor about the events of the previous day. He was busy in the laboratory with the two skeletons, and remained secluded.

"What do you think the Professor found in the cave while we were getting the team?"

"I have had a curiosity to know, as well as yourself. Shall we ask him?"

"I do not think it would be well to do so. You know he is always willing and anxious to be of service to us and to answer every question; it looks like an imposition to insist on what he evidently wishes to avoid."

"That is the feeling I have had. I love him because he has been so unselfish, and during the time we have been associated, I do not remember ever having heard him utter an unkind word."

"I have often thought I wish we knew of some way to make him understand how we appreciate him and his noble ways. You remember the birthday party we had for him? That touched him, as it did us, and it was the only time I ever saw him confused or in tears."

"I wish we knew his history. Did you ever hear him say a word about his friends or relatives? What affects me most is, that when any subject comes up, he always considers it from the standpoint of service to us. He never considers himself."



CHAPTER VIII

REMOVING THE VESSELS FROM THE CAVERNS

The boat was finally completed, and the boys were very anxious to have a sail in it to know how it would act. The utmost care had been taken to have it well caulked, and it was again put into the water, after all the leaky spots had been closed up.

For the purpose of the test it was decided to put aboard a load of stone, of a weight equal to what their contemplated load would be, and this they estimated, not counting their combined weight, at six hundred pounds. This would be ample for all purposes.

The day selected was bright, with a fair wind. By agreement Harry was selected as the skipper, as he knew every part of the boat. It devolved on him to take command for the day, but he would not consent to be the permanent captain, as he thought that a duty which devolved on the others as well.

Angel was invited, you may be sure, and he enjoyed the idea of a sail when he recollected, as was no doubt the case, his former trip. There was evidence of the remembrance in the animal, when they saw him at the boat, on more than one occasion, swinging back and forth on the rigging.

The Professor was in his element in the boat. It was a glorious journey for him, and the boys knew it was appreciated on his part. The wind was blowing from the west, so the sails were tacked and an easy sail made for the mouth of the Cataract.

Outside the sea was rolling, but not disagreeably so; but a much stronger breeze sprang up toward midday, and before two o'clock it was very brisk. The cliffs were rounded, and as the wind had not changed quarters, the sails were set for a southern course. This brought them around the bay and toward the headland to the east of the mouth of South River.

That region had always possessed a fascination for George and an attraction for the Professor as well. George, particularly, was anxious to penetrate the river, and sail up to the falls, but Harry's more practical views prevailed. "If we want to explore the river we can do it any day with a wagon, or on foot; but while we have the ship out, why not take a sail down the coast toward the mountains?"

The Professor concurred in this as the most liable to give them the best results, as they were out for the purpose of making tests of the craft on the open sea.

After sailing for an hour along the coast to the south, the shore line turned to a southwesterly direction, and the mountain range was now clearly perceptible, extending southwest, and along which it appeared that the coast followed. The wind changed and came from the mountains, and made progress slow. There was also a decided change in the temperature, and by four o'clock it was impossible to follow the coast except by constant tacking.

The boat was turned to the north, and with the strong wind, which had now perceptibly increased, began to make good time. As evening approached, the wind increased, until it blew with considerable violence, every minute being more boisterous, and the Professor suggested that the jib be taken down, which was done; but the increasing gale, and the terrible strain on the mast and sail, made the boys look inquiringly at the Professor, for a word of warning.

He sat there grimly during the raging storm, and with the halliards gradually let down the mainsail when the tempest had reached such a point that it appeared to sweep everything from the boat.

Where was Angel during all this uproar? Forward in the housed portion of the boat, curled up in a corner, and apparently unconscious, the little creature did not seem at all perturbed.

"Don't you think he is seasick?"

"It is not likely. Seasickness is akin, you know, to that dizzy feeling some people have when at a height. The natural instincts of the animal prevent him from having any feeling of discomfort at a height. The trees are their homes, and for that reason they can swing from branch to branch and sway back and forth in the loftiest trees without an uncomfortable feeling."

The heavy blow continued until they had reached the cliffs, when it abated somewhat, and the boys anxiously inquired whether it would be safe to make the entrance to the river during the gale.

"We are out for the purpose of testing the boat. To make an attempt to round the cliff and steer it into the mouth of the river in this wind will be the best test of its maneuvering ability."

As stated, the wind was now blowing from the southwest, and they were northeast of the mouth of the stream they wished to enter. They stood out to sea in order to make a starboard tack, and it was a gratification to see the magnificent manner in which the vessel responded, and before six o'clock they found themselves sailing up the river, and safely landed at the boathouse.

An examination showed that the crossbeam supporting the mainmast was split from end to end, and only the roof structure held it in place. Thus the trip had a warning lesson for them, and Harry was not slow to take advantage of it and install a larger crosspiece.

George had entirely forgotten the incident of the calcareous slab which had on it the tracings of the cave, and which had been the means of giving the Professor the first hint that they were in a pirate's cave.

The first thing in the morning he went over to the laboratory, and called attention to the slab. "Here it is," said the Professor. "You will note that the light shows some characters which can readily be made out, and at the corner here, where a portion has been chipped away, it has the appearance of something else besides calcium."

"Why, it looks like wood."

"That is what it is. I should not have noticed the wood if the peculiar lettering had not shown up through the coating."

"What are the letters, and do you know what they stand for?"

"We had better not pass judgment on that until we have removed all the calcium."

At this moment Harry came in to view the slab. It was the slab he had carelessly picked up in the cave, and therefore it had a great fascination for him. The calcium was carefully chipped off, and it was found to be a piece of oak board, with a smooth cut-off end, parallel sides, nine inches wide, nearly two inches thick, and about eleven inches long, the opposite end having the appearance of being broken. The only letters which could be made out were "HI," and a portion of another letter which could not be determined.



"What do you think the letters were intended to indicate?"

"They might be the name of a ship, or some sign. I do not think it was part of a ship. I tried to find something in the cave, on the day I went in while you went after the team, which would afford some clue, but so far nothing confirms me in any view which I may have."

"Isn't it curious that these letters should show through only after the slab was exposed to the light?"

"Why is that any more curious than photography is?"

"Because in photography something is put on the glass or the sheet that the negatives are made of, and it turns and makes a mark under certain conditions."

"Well, here is something put on this slab that turns also. Photography is a wonderful thing. Dr. Draper, the first great photographer, and who was also a scientist, says that every wall, or other object, which you stand before, has your photograph imprinted on it. The only question is to find some chemical which will develop the picture."

"What is meant by developing the picture?"

"You remember some time ago we talked about reagents, and the properties of certain chemicals to act on others, and in doing so, to make a change. Sometimes the change is a complete one, and makes a new product; in other cases the result is a complete change of color. Now, in photography, if a certain chemical is placed on a glass or a film, and the film is exposed, the light and dark portions of the object show on the film. The sunlight, or the actinic rays in the sunlight, affect the chemical material so that when the fixing chemical is applied it prevents a change in the condition of the chemical."

"What do you mean by the actinic ray?"

"All light is vibration; the greatest motions which are perceptible to the eye, being known as violet. Now there are still more rapid vibrations than are put forth to make the violet rays, which are called the actinic rays, and are the ones which affect the chemicals so acutely."

"Is it then possible to photograph with a light that is not perceptible to the eye?"

"You have heard of the x-rays, no doubt; they are the actinic or ultra violet, which are above the visible light. These light vibrations are of such a character that they penetrate many substances. A curious effect of this was shown some time ago when a photograph was taken of the side of a vessel which had several coats of paint over the old name, and the photograph showed not only the new name, but also the old one beneath."

The time had now arrived when they must make preparations for the proposed voyage of discovery around the island. It was a momentous time for them. The boys could not help but look with longing eyes to the cave. Before they went it was felt something more should be learned about its mysteries.

The Professor was not at all backward in encouraging this feeling.

"Wouldn't it be a good thing to take such things out of the cave as we can make use of here, and during our trip?" said Harry.

"What things do you think we could utilize?"

"Probably the guns; and then they have some cooking utensils."

"And why," suggested George, laughingly, "couldn't we take some of the money along?"

"That would be a comfortable feeling to have plenty of money in our pockets. Very well, we'll take this afternoon for the trip."

An early start was made, the lamps carefully trimmed and the guns, together with the bolos, collected. It was a short walk to the opening, and Angel, although not invited, accompanied the party.

Together they descended, and soon reached the scene of the conflict at the large recess to the left of the entrance. The Professor, after reviewing the scene, suggested that the bones should be carefully gathered together and deposited at a place where they could be buried.



"We do not want them here as evidences of the strife."

After all had been gathered and carried to the spot selected, the first task was to gather the treasure found in the chests. And here a sight met their eyes which staggered them. One of the chests which Harry first found contained not only an immense quantity of gold coin, of Spanish and other mintages, but curious other pieces, all ancient, as shown by the inscriptions, and long yellow bars, the last of which attracted George's attention.

"What are these bars?"

"They are gold bullion, made by melting up various articles, and probably the coin itself, so as to make it convenient for transportation."

"My! how heavy they are! and look at the number!"

When all had been assorted the Professor suggested that as they had plenty of copper utensils, the latter might be used as receptacles for the gold. The other chest contained but little coin, but here the interest was not less pronounced than in the other chest, because the vessels found were not only of beautiful, but many of curious, design. Some were of silver, as well, and the boys knew that those would be serviceable for their table, and at their suggestion all such were laid aside to be removed to the Cataract.

The kitchen utensils afforded a more varied collection than had been anticipated. Six of the larger copper vessels were required to hold the money, jewelry and other articles taken from the two decayed chests, and there were still remaining at least a dozen more smaller jars and pots, some with handles, which would be exceedingly useful in their kitchen.

All these were carefully put aside, and the smaller silver articles deposited in them. And now the guns! Seven skeletons were found, two of which had been removed to the Cataract by the Professor. After all the guns had been collected, twelve were counted.

"I suppose each fellow had two of them," was Harry's conclusion.

"If you will go over into the chamber to the east you will find a sufficient number to assure you that they were not lacking firearms."

The boys now understood. He had told them on the second day's exploration that he did not find anything new, but only something more. Why not go and see it now. But they were restrained. A dozen guns were certainly enough. These were also set aside, and it was then agreed to place the vessels containing the treasure in a secluded nook, in the extreme corner of the large recess. Samples of the clothing, some of the knives or daggers, as well as the little trinkets, found near each of the bodies, were deposited in the receptacles that had been selected for removal.

All this accumulation of material was more than they had bargained for when they left the Cataract, so that the failure to bring the team was keenly felt. However, it was the work of an hour, only, to get the team, and it was a pretty fair load which went from the pirates' haunts to the home on the river.

George's curiosity could not keep him from taking some of the coins which he exhibited when they returned, and which they would have ample leisure to examine.

Harry's thoughts were turned to the firearms. They were certainly of an antiquated pattern. The first thing was their length. Two of them were unusually long, fully six and a half feet.

"I wonder why it was they made their guns so long?" he inquired.

"The reason was, probably, that the quality of powder was so bad that the bullet would get out before all the powder was consumed. All the ancient pistols were very inefficient, because of the short barrel. Even down to the time of the American Revolution the guns on board of war vessels were not capable of throwing shot very far, and the most effective ones were those with long barrels."

"In what respect is the powder of to-day more powerful than in olden times?"

"Particularly in the fact that formulas have been devised which make a higher expansion, or give a greater volume of gas. The other feature of value is, that chemical means have been discovered whereby the moment a sufficient amount of heat has developed in the powder it instantly burns—not a slow fusing, like the old powders—but the combustion is instantaneous. These two factors working together have greatly improved even the black powders."

After their return the interest in the articles was so great, and the inventory took so much time, that the disappearance of Angel had been entirely forgotten. All remembered him going along, and no one had seen him enter the cave. None of them believed he could be induced to go in, hence no particular notice was taken of his movements.

An hour after the return, Harry saw Angel coming over the field at the east of the Cataract, dragging something after him laboriously. All stood and watched him as he neared home. He had a stick, apparently, but it seemed to be unusually heavy.

George ran out to assist him, and when he came up he gravely handed to article to George. It was the barrel of a gun, with part of the flintlock still attached, but it was rusted almost beyond recognition, the bore completely filled with dirt, accumulation and rust.

"Where do you suppose the little rascal found this?"

The Professor examined it. "Outside of the cave, undoubtedly. The curious part about it is, that this weapon is of an entirely different and more modern pattern than those we have samples of."

Harry took the gun and ran in to where the others were deposited, and true enough, it was not only shorter, but it had a smaller bore, and what is more, the outside of the barrel was octagonal, whereas the barrels of those inside of the cave were all round.

As the Professor predicted, the guns which they recovered were too much rusted to be of any service, and furthermore, they were made of iron, very much softer than the steel of which their own guns were constructed, and it is questionable whether they would be able to withstand a charge of the comparatively high power powder which had been made for the modern guns.

As curiosities the weapons were good things to have; otherwise they were of no value. This was not so with the vessels, which could be and were utilized in the kitchen and in that capacity were of the highest use. The table was supplied with articles of the purest silver, and it had a royal look.



CHAPTER IX

MAKING ELECTRICITY

In order that you may get some sort of idea concerning the condition of our little colony, at this time, it would be well to give a brief review of the situation. When they landed on the island the year before, with nothing but the clothing they wore, the prospect of being delivered was not a flattering one, as day after day passed by.

Here were two boys, unused to the privations of life, with youth and vigor, cut off from all the pleasures of manhood, surrounded by dangers, and day after day having mysteries thrust upon them which only increased their fears. These things necessarily must have produced an impression much deeper than would be the case with hardened men.

In the effort to discover, produce and build the various tools, weapons, and articles of clothing, to hunt food, and in the endeavor to learn about the condition of the island, and guard themselves against foes which might be all about them, imposed immense responsibilities.

In their struggles were personified the contests of the human race from the beginning of the world, in the effort to conquer nature, and to make it contribute to their necessities.

The Professor knew how such a condition would tend to make active minds either productive of good, or to fly out in the opposite direction and cultivate the low and sordid instincts. Occupation, work, the utilization of the mind, and above all, to direct their energies into useful channels, had been the Professor's one absorbing aim.

The boys had responded, as all boys will, not for the love of gain or for power or glory. Our boys had none of these. Other boys do not need them any more than those on Wonder Island. What they do need is a true stimulus for work; and when that evening they were gathered together in the cozy little living room at the Cataract, the Professor who for two days had been particularly reticent and retired, said:

"Can you imagine the condition of the pirates who gathered all that hoard in the cave? What do you think their aim was in life?"

"It seems to me," was Harry's reply, "that the only thing they were after was wealth."

"If what we see in the cave is any indication, the principal thing they lived for was to kill somebody," was George's conclusion.

The answers made him smile. "You have, I presume, answered the question in the two sentences. But there is something that you haven't mentioned, which is at the bottom of it all."

"Yes; wanting to kill to get the money."

"That only states your previous answers in a more concrete way. There is one word which describes it accurately: Selfishness. When a man inquires into the secrets of nature; when he tries to turn the knowledge gained into account, either for money or glory; when he consistently devotes his days to labor, and his nights to thoughts to find out how he may do something better, or quicker, or cheaper, it might all be denominated selfishness, and so it is, in a way. It is a selfishness, however, that does no injury to a fellow-man. That kind of selfishness is the great quality which has produced the wonderful things that we see all about us, and which distinguishes the man from the brute creation."

"But I have read of a great many men who made millions and millions and who never did any of the things you have just referred to," answered Harry.

"Then do you think they are any better than the pirates were?"

Notwithstanding the exciting times, food was a necessity, and it had to be found and prepared. It could not be bought. All the gold in the cave would not purchase a single meal. More barley had to be ground and the stock of honey was almost exhausted. Their duties in the shop, consequent on the haste exhibited to get the boat and weapons ready, contributed to the low state of supplies.

George announced that there was less than two pounds of the honey left, and proposed that a trip be taken to the flats, where the Professor had found the sugar cane. All joined in the journey to the cane field, and Angel was invited to join, which invitation was accepted by him gleefully.

The bolos were taken for the purpose of cutting the cane, and on the way George's inevitable question point was in evidence. "What did people use for sweetening purposes before cane was discovered?"

"Honey was the principal source of the world's sweets. But cane is not the only kind of vegetable from which the principle has been extracted. There are many kinds of reeds which furnish a sweetish substance. Sugar cane was first made known in eastern Europe by the conquest of Alexander the Great. Nearchus, one of his admirals, in sailing down the Indus, found the reed, and it was, previous to that time, known throughout the greater part of India. He described it as a kind of honey growing in canes and reeds. From this you may infer that honey was the principal source of sweets in his time."

"What are the other principal plants or substances that sugar is made from?"

"Mainly from beet, tubers of various kinds, such as the common dahlias, and numerous vegetables, from milk, fruit, gum arabic, as well as fish."

"I have heard it said that sugar contains all that is necessary to sustain life. Is that true?"

"That is a mistaken idea. It will sustain life for quite a time and with the addition of nitrogenous matter has great fattening properties, but without that it is not valuable as food."

"What do you mean by nitrogenous matter?"

"Meat, fish, eggs, milk, beans, peas, and the like, all contain a large amount of nitrogen."

"I remember my arm being burned on one occasion, and mother made a syrup out of sugar and put it on. In what way was the sugar beneficial?"

"In the first place, sugar is one of the most powerful antiseptics known. It acts, therefore, as an aid to healing, since it protects the wound from foreign substances and from poisonous and harmful germs. In the next place, it is a great preservative for either fruit or flesh."

The cane was cut close to the root, and the top and leaves trimmed off. Within several hours a full load was thus procured. The boys enjoyed the pith, and George playfully gave some to Angel. His surprise knew no bounds. When he knew what the cane was good for, he simply gorged on it.



Harry at once set to work on turning up two rollers from hickory, the rollers being eight inches in diameter, and eighteen inches long, and each being provided with a spindle four inches in diameter. One end of each of the spindles was longer than the other, so pulleys could be attached, the object being to provide a means whereby they might be turned by suitable belts from the water wheel. In addition, the top roller was made so it would yield, and had levers resting on the spindles, and provided with weights, so the rollers would press out the juice, whatever the quantity that might be placed between the rollers.

It was really a simple little machine to put up, but it required a day for both of them. Vessels were now provided for the juice, and when they were filled, the Professor suggested that a little lime should be put into the juice, after it had been strained through the ramie cloth.

"What is the object of putting in lime?"

"To precipitate the impurities."

The action of the lime was plainly visible, and after it had been allowed to settle, the clarified portion was drawn off, and the process of boiling down was proceeded with. As fast as one of the vessels was boiled down, more of the cane was crushed, the juice being dipped from one vessel to the second one, until the entire load was crushed and the juice boiled down to a thick consistency.

Here was molasses, at any rate a good substitute for honey, and it was so homelike to get the real article. That night they had molasses candy. It felt like old times. It was a real candy pulling, and no one enjoyed it more than Angel. From the moment he had the first taste of the pulp of the cane, he was the most interested one of the party. But the fun came the next morning, when George brought out, for his benefit, some of the taffy which had been set out to harden. The chuckle which he emitted, when he tried to pry off a piece of the sweet morsel, was too amusing for words.

When the entire amount of juice had been boiled down and it had readied the point where it had the appearance of granulating, the fire was withdrawn, and the whole mass stirred until it was cooled, and the result was a fine sample of beautiful brown sugar which weighed forty-three pounds.

Nevertheless food was an important item in their preparations, the necessities for doing everything in their power to insure the success of the maritime enterprise. One of the most valuable adjuncts for sailing is a compass. No attempt had been made to produce the implement, and when the needs of the expedition were being discussed, Harry was curious to know the reason why the compass always pointed north and south.

The Professor was very much interested in all electrical phenomena and replied: "The earth is a huge magnet, and any body which is magnetized has a north and a south pole. The needle which is also a magnetized body has, in like manner, a north and a south pole."

"But in what manner does that make the needle point in one way only?"

"Electricity is a very curious thing. While the current unquestionably moves from one end to the other of a conductor, it also exhibits itself in the form of rings around the wire. This may not be understood in the absence of a sketch. For that purpose I make a drawing (Fig. 17) which shows a conductor (A), through which a current is passing, and this current is represented by the spiral line (B) which goes around the conductor."



"Well, is magnetism the same as electricity?"

"Both exhibit the same manifestations. Magnetism is nothing more than a body charged with electricity. The electricity, which appears to travel around the conductor (A), extends out for some distance from its body, and produces what is called a magnetic field. This is the case whether the magnet is a permanent one, like the earth, or whether the conductor is charged by a dynamo."

"What is the difference between the north and the south pole?"

"There is really no difference. The terms north or south and positive or negative are mere relative designations, and are distinguished simply by the movement or direction of the travel of the current. You will remember when we made the battery, it was shown that the current, outside of the battery, moved from the positive to the negative pole. That was merely stating that it moved from the north to the south pole outside of the earth, and from the south to the north pole inside of the earth. The current is, therefore, from one magnetic pole to the other."

"What I cannot understand is why the magnetic poles should be at the north pole and at the south pole."

"The magnetic poles are not at the poles of the rotation of the earth, but hundreds of miles away, to one side of the poles on which the earth rotates; but they are near enough to the real poles, for all purposes, so that the needle points to what we call the north pole of the earth. Any magnetized body must have these two opposite poles. If it is a body, like a bar of iron, one end is called north and the other south. Look at this other sketch (Fig. 18) and you will see how the currents flow in the two magnets. In this case the large body (E) represents the earth and the small body (M) the magnet. Now notice that the current going around the large body moves to the right, or to the north pole, whereas the current in the small magnet (M) flows in the opposite direction."



"And does the current flowing around the bars, as you have shown, make the small magnet turn around so that it is always parallel with the large magnet, and make the north pole of one magnet at the same end with the south pole of the other magnet?"

"Yes; to make it still clearer, I make two more drawings (Figs. 19 and 19a), in which two sets of magnets are shown. In the first of these pairs of magnets (Fig. 19), the two north poles approach each other, and the two south poles are opposite each other. The currents, if you will notice, at the north poles move toward each other, and at the south poles move away from each other. They are, therefore, acting against each other, and the result will be that the magnets will move away from each other. If, now, one of the magnets is turned so the poles of one magnet approach the opposite poles of the other magnet, as shown in the second view (Fig. 19a), they will attract each other, because the current is permitted to flow through the two magnets in the same direction without one conflicting with the other."



"Is that the reason it is stated that likes repel and unlikes attract?"

"Yes."

In order to take advantage of this knowledge, knowing that the earth is a great permanent magnet, it was necessary to make a small magnet, and so suspend it that it would turn freely, and the magnetic north and south could then be determined.

To do this the battery which had been previously made was brought into play. George took a hand in the work, and while they were preparing the metal for the little bar, said: "You spoke about a permanent magnet. What other kinds of magnets are there?"

"Magnets are permanent or temporary. A permanent magnet is one in which the electricity resides, or remains, as it does in the earth. A temporary magnet is one which has magnetism imparted to it only while a current of electricity is passing around it."

"How is the current made to pass around it?"

"By wrapping an insulated wire around it, and sending a current through the wire. When that is done the same thing is done to the bar as the bar of the permanent magnet exhibits. As soon, however, as the current through the wire ceases, the bar is again demagnetized. That is, it ceases to be a magnet."

"We have the small bars ready, Professor. What is the next step?"

"It must be hardened so as to make it a flinty steel. The harder the better, so that it will preserve the magnetism imparted to it."

"Is that the better way to make the temporary magnet?"

"No; in that case the bar should be of the softest iron. Remember, therefore, that for a permanent magnet, use the hardest steel, and for a temporary one, the softest iron."

"Then as we want to make a permanent magnet, must we harden both of the bars?"

"No; for our uses, one must be left soft, because on that we shall want to wind some insulated wire to make a temporary magnet."

The small amount of wire which was on hand was then coated with a thin layer of the ramie fiber, which was carefully wrapped around, so that the different layers of wire could not touch each other. When this was completed, a spool was constructed, which fitted over the little bar or rod, because they were rounded off, and one end of the soft iron rod extended out beyond the spool.

The opposite ends of the winding were then brought out and attached to the terminal wires of the battery. A test showed that the magnet thus made would readily pick up pieces of iron or steel. The Professor then took the hardened steel rod, through which a small hole had been bored, midway between its ends, and laying it down on the table, the projecting end of the temporary magnet which projected from the spool was put into contact with the hard steel rod, and slowly drawn along to the end. The soft bar magnet was then raised up and again repeated, as shown in the drawing (Fig. 20), where the dotted line (A) represents the movement of the end of the temporary magnet.



This was repeated over and over a great many times, and finally the hard steel bar was found to have a charge of magnetism, and for the purpose of providing a means for holding the magnetism, a C-shaped piece of iron was put on the bar, as shown in the detached figure.

"Is that the reason," asked Harry, "why a small piece of metal is always put across the ends of a horseshoe magnet when it is not in use?"

"Yes."



CHAPTER X

STARTING ON THE VOYAGE TO THE WEST

"If I remember correctly, you stated some time ago, Professor, that the barometer indicated the pressure of the atmosphere, and in that way it was useful in letting us know what the weather would be. Before we sail, would it not be well to make one of them? If we had possession of one of the articles, we might not have been caught in the storm the first time we took out No. 3."

"That is a good suggestion. I intended to propose that, because with the barometer and the compass we shall be equipped with two of the most useful instruments needed."

"I cannot comprehend how the air pressure has anything to do with the weather. Is the air pressure really greater at one time than at another?"

"Heated air ascends, does it not?"

"Yes; I can understand that."

"As it ascends it is, therefore, lighter at that point than normally. On the other hand, moist air is heavier than dry air. These two conditions would be indicated by the barometric column, would they not?"

"I presume they would; but when the air is moisture laden we don't need a barometer to tell it is going to rain. We know it and feel it. What I particularly wanted to know was how the barometer by its actions would indicate it ahead for any length of time."

"The barometer does not indicate with any degree of accuracy on land; but on sea it has a much better application. The instrument shows the present pressure of the atmosphere, and its variations correspond to atmospherical changes which have already taken place, the effects of which may follow their cause at a greater or less interval."

"Then how could it be ascertained from the instrument when there would be a storm or rain?"

"After a continuance of dry weather, if the barometer begins to fall slowly and steadily, rain will certainly ensue; but if the fine weather has been of long duration, and the mercury may fall for two or three days before any perceptible change takes place; the more time elapses before the rain comes, the longer the wet weather is likely to last."

"Then what indicates dry weather?"

"If, after a great deal of wet weather, with the barometer below its mean height, the mercury begins to rise steadily and slowly, fine weather will come, though two or three wet days may first elapse; and the fine weather will be more permanent in proportion to the length of time that passes before the perceptible change takes place."

"Is this the case at all times of the year?"

"The seasons affect the barometer, it is true. A sudden fall of the barometer in the autumn or in the spring indicates wind; in the summer or in hot weather it prognosticates a thunderstorm; in winter, after frost, a sudden fall of the mercury shows a change of wind or a thaw with rain; but in a continued frost a rise of mercury indicates approaching snow."

"It seems, then, that a man must be pretty well versed in the weather to be able to read the signs."

"That is a correct observation. The instrument in the hands of one who has had experience with its use is absolutely necessary; it is not a very satisfying device for those who do not take the time or trouble to read all the signs, and note all the indications."

As detailed in a preceding chapter, the hardened steel rod for the compass was brought out for the purpose of securing it in a little case, so that it might be utilized to give them the true north.

It was a difficult task to find a means of suspending it, for the reason that they had no tools which would make fine and carefully pivoted balances, but eventually this was done, and they were gratified to see the little rod or bar swing around and point north and south.

The work of arranging suitable closets for the various provisions and providing a miniature kitchen was the next thing in order. This occupied several days. Instead of taking the bedding in their house, it was decided that new mattresses should be made up from the barley, of which there was quite a quantity on hand.

One of the receptacles taken from the cave was a copper jar, which held five gallons of water. A top was made for this which could be sealed up, to hold a reserve supply of water. In addition two other vessels were also provided for the regular supply, and also fitted with covers, so that they had about ten gallons, an amount which was considered sufficient.

The matter of fuel was a more difficult one to solve, unless they intended to prepare most of the food before starting; but George insisted that the small stove should be put aboard, and about fifty pounds of the coal stowed away.

"How long do you think we should provision for?" was George's inquiry, as they were carrying the various things aboard.

Harry had no ideas on the subject, but the Professor ventured the opinion that at least two weeks' supply should be arranged for.

This conclusion rather startled the boys, who had not expected more than a few days' trip, and when they questioned him about his reasons for making the statement, he said: "Did you ever hear of the old lady who attended a special meeting of prayer for rain? She came with an umbrella, and the people laughed and chided her. The minister reproved them, saying: 'She, at least, has faith, which you have not.' We are going for two purposes: one is to learn something about the island we are on, and the other to rescue our companions if they can be found. We couldn't rescue them and let them starve."

Those words impressed them as nothing theretofore had, that the Professor believed they were really going to find their former shipmates, and that they would have stirring times before them.

Nothing so stimulates the actions of men, or boys, as the prospect of adventure. Their trip had a double meaning, and it is not venturing too much to say that their feelings were most tense during the entire period in which they were engaged at the task of fitting out the little ship.

At last the day was set for the departure. The cattle could take care of themselves. A tablet was prepared to be put up on their dwelling, stating who were the owners of the habitation, their present destination, and briefly relating the knowledge they possessed of the inhabitants of the island, a statement of the direction they had taken, and the kind of boat to which they trusted their destiny, and when they expected to return.

A copy of this was then carried to the pole on Observation Hill, and nailed to the mast, to replace the small tablet which had hitherto filled that place. They were to launch the boat for the start on the morrow.

That night a storm blew up from the west, as most of the winds had previously blown from that quarter during the past month. The storm was severe during the entire night, and abated somewhat in the forenoon, but it again increased in fury before noon and continued with more or less vigor all that day and during the night.

"I am afraid this storm will prevent us from starting for several days, on account of its widespread character. The sea for hundreds of miles has been subject to this monsoon, and we would have a very rough time until the sea quiets down."

The delay was a bitter thing for the boys. Expectation had run high. Anticipation doesn't mildly or easily brook waiting. They did not know what to do, or how to pass the time in the interim. It was such a new and trying condition for them.

The Professor noticed how they chafed under the restraint, but apparently took no heed of it. However, he encouraged them in every effort they made to divert themselves and to occupy their minds during the waiting period.

During one of these spells which come on all more or less during such trying hours, George could not hold in any longer, but broke out impatiently: "What is the use of waiting any longer? The storm may keep up for a week."

"Then do you think we had better venture a start under these conditions?"

George thought a while. He appreciated the risk. Harry, too, was anxious and nervous, and expressed a willingness to take the risk.

"Let me put another side to the question," said the Professor. "We are perfectly safe here. You take no risks by remaining. You have in the cave treasure that will make you millionaires. You cannot afford to take any risks. If we knew something of the conditions on the island, and had a certain knowledge that our comrades were in danger, the considerations I have named should not deter us from starting. But with all these things in the dark, and with the monsoons likely to break out again at any time, the question is whether we can afford to risk the safety of the enterprise because of impatience at delay."

"Yes," answered Harry. "I have thought of these things, and I feel that the Professor's advice should be followed."

The boys were particularly surprised that he should refer to the money in the cave as a reason why they should consider their actions in the matter. It was so unlike him to refer to any sordid considerations as a reason for not performing a great duty.

"I would also remind you that one of the greatest boons ever given to the great investigators of the world came through delays. Time is a wonderful reasoner. It is also a great modifier of events. Darwin was prevented for twenty years in promulgating his great thesis; some of the most marvelous inventions took years to bring out and develop into such a state as to make them acceptable to the world. Delays, patiently borne, make strong men. The impetuous think they represent wasted opportunities. Davy Crockett enunciated one of the greatest principles of human action when he said, 'Be sure you are right, then go ahead.' It was only another way of advising against recklessness or impatience in any enterprise."

Thus three days passed, and not without misgivings, the signal was given for the start. Angel accompanied them, and with a new flag which the days of leisure had given them an opportunity to prepare, the little craft sailed down the waters of Cataract, in a shining sun, bound for a haven which might mean rest, or to a shore which might offer no welcome to them. The wind was coming mildly from the north, and when they had cleared the shore line and were beyond the influence of the swells, their course was directed to the west. Several miles beyond was a point which projected out to sea; they could see this plainly from Observation Hill, and during the last long trip inland they reached the sea beyond this cape.

The shore line beyond was absolutely unknown to them, but it extended to the west as far as they could see, and when night set in the faint mist prevented them from judging how much farther it ran in that direction.

Without proper instruments at sea, distance is always a difficult matter to judge, and the boys were constantly venturing guesses as to the distance traveled. The start was made shortly after nine o'clock, and it was now past six in the evening.

"How far do you think we have gone during the day?" was George's question.

The Professor made a mental calculation before replying. "If we have traveled at the same speed during the entire course that we made during the first three miles to the cape, we have gone about thirty miles."

"Do you know it is three miles to the cape?"

"Yes, it is approximately that distance. I measured it by triangulation some time ago, using our house and Observation Hill as the base line."

The boys had neglected to take this precaution.

"What was your object in doing that?"

"So that we might have some means to observe the speed our boat could make. If we knew the speed of the wind, we might be able to calculate our distance."

"But the wind has been coming from the north and we are sailing due west. Would not the difference in the speed of the wind make a difference in the speed of the boat?"

"It was for that reason I stated if our rate of travel was the same we would have made that distance. The wind has been variable at different points along the coast, so that our average may have been four miles per hour."

"At what speed has the wind been during the day; I mean the average speed?"

"Less than eight miles an hour?"

"If the wind had been coming from the east we could have made much better time, and we might then have been near the mouth of the West River," was Harry's conclusion.

"Why do you think we should have made better time?" asked the Professor.

"Because we should then have been going with the wind."

"You are entirely wrong in your assumption. Sailing ships travel faster when tacking than when sailing with the wind."

The boys looked at the Professor in astonishment.

"It does not seem possible," replied George, "that any movement of the wind pushing sidewise could be more effective than a pressure straight ahead. Can you explain the reason for the statement?"

"When the wind blows straight against a sail, certain eddies are produced which cause a convolute stream around its edges. These currents are counter to the forward movement of the vessel. Assuming that this normal pressure of the wind is 1,000 pounds, it is estimated that fully half is lost in effectiveness. On the other hand, if the ship is moving forward at right angles to the direction of the wind, and the sail is set at forty-five degrees, that is what is called a tack; while it has only about six-sevenths the surface that it had when going with the wind, the sail is constantly going into new wind and, therefore, the pressure is a constant one and most efficiently applied to the surface."

"Do you mean by this that if I hold up a sail so that the wind blows flat against it, the pressure will not be as great as if I held it at an angle?"



"No; I had reference to a moving object. I can better explain the phenomenon by illustrating the two conditions: In the drawing (Fig. 21), let A represent a sail with 100 square feet of surface. The darts (1) represent the wind blowing dead against it. This is called the normal position. You will see the darts representing the direction of the movement of the wind. Now look at the next sketch (Fig. 22). Here the sail (B) is put at an angle of forty-five degrees from the direction of the wind. The sail is still the same size vertically, but it is somewhat smaller horizontally across the line (C), this diminution in size being about one-seventh of the entire area. The darts (D) in both cases represent the movement of the boat, and the darts (2) in the last sketch show the wind striking the sail at an angle."

"In the first sketch the darts (1) strike the sail normally, as you say, in what way do the darts (2) in the next figure strike the sail?"

"At an angle of incidence. If you will notice the behavior of the wind in the first view it will be seen that the wind curves around the edges of the sail, and strikes against the back of it, and thus produces the retarding effect I referred to. On the other hand, by examining the second sketch, the darts (2) plainly show their course across the sail diverted from their straight source, and behind the bulging sail the air does not press against the sail, but tries to continue in a straight line. As a result a partial vacuum is formed along the region designated by E, and this produces a most effective pull, since the sail constantly tries to move forward and fill this vacuum. Is this made clear to you?"

"I can plainly see now what the action of the air is, but does the air push just as hard against each square foot when it is at an angle as when it is blowing against it straight?"

"That is a good observation, and one that might ordinarily be overlooked. No, it does not, but the difference can be readily calculated."

"Then supposing the sail to be 10 feet square, and the wind is blowing against it straight, as in the first sketch, at the rate of twenty miles an hour; what pressure would there be against the entire sail?"

"At that speed of wind the pressure on each square foot of surface is 2 pounds, and this multiplied by 100 equals 200 pounds."

"When it is at forty-five degrees, what is the pressure on each square foot?"

"This is determined in the following manner: Square the speed of the wind, which means multiplying 20 by 20, and this produces the square, 400. In mathematics, as in many of the sciences, a constant is employed. A constant is a figure which never varies. In this case the constant is designated by the decimal .005. That means 5/1000th, or reduced to its lowest denomination, 1/200th. If, now, we divide 400 by 1/200, the result will be 2 pounds. This figure thus represents the pressure of air on each square foot of surface, which, multiplied by the sail area, 100 square feet, makes 200 pounds."

"If that is the push when it is normal, what will it be at 45 degrees?"

"Each angle of incidence has its own figure, or coefficient, or for your better understanding, value, and the value at 45 degrees is .666. So that by multiplying 200 by this value, we get a total pressure of 133.2 pounds."

"These figures are used a great deal in flying machines; are they not?"

"Yes; and that is a subject which we might pursue, but there are some things right ahead that may for the present interest us more."

Through the haze which had now settled down, a faint outline of land was made out in the distance. The course was altered to the northeast, and after a quarter-hour sail, land was again espied ahead, so that to avoid the shore the course was taken due north. This was evidence that the land projected northwardly, and the Professor suggested that the effort should be made to chart as accurately as possible the shore line. This could be done mentally.

"I had forgotten to take any note," said Harry. "What is the proper thing to observe in making these calculations?"

"Two things must always be uppermost in the mind of the explorer on the sea: First the time, and second the speed. Time can always be accurately determined, but the question of speed can come by experience only. A good sailor can very accurately determine speed by an examination of the passing water, where the sea is comparatively calm. I have known where the distances have been thus estimated within a hundred feet in each mile in a ten-mile course, and where the speeds were varied along the route. Then, a good observer must have the gift of direction. If he has sailed one hour at a certain speed in a given direction his mental chart may be of the greatest service to him. In our case it would be invaluable. It is a quality well worth our effort to acquire."



CHAPTER XI

A TERRIBLE VOYAGE AND THE SHIPWRECK

The shadows of night were now upon them. How vividly it recalled to their minds the horrors of the five days and nights during which they were tossed about in the little lifeboat a year before. Then they were helpless, and now strong. At that time everything was dark and gloomy, without a ray of hope. Contrast the situation at this time.

What a gratification it must have been to look back during the past twelve months and mentally calculate what they had accomplished. They had delved in many of the hidden mysteries of nature and learned the secrets. Such knowledge had been put to use. They had discovered many things that gave them pleasure, but in doing so found others that startled and grieved them. Things inexplainable and impossible to fathom had crossed their paths on almost every side.

But they were now doing the work of men. The Professor knew how they had developed, and grown brave and strong. He knew it better than the boys could realize themselves. What a source of pleasure it must have been to the kindly faced, gray-haired Professor, as he looked at his charges in admiration and love. Could anything be more inspiring than the contemplation of the work he had done?

And now the inevitable charting board was brought out, and the plan adopted which would enable them to trace the coast line. It was explained that all sailing was by the points of the compass, and for this purpose the compass was made to correspond with the regulation instrument. This is shown in Fig. 23.



The four cardinal points are north, south, east and west. Exactly midway between each of the four points are the divisions designated northeast, southeast, southwest and northwest. Then, again, intermediate, the last divisions and the cardinal points are other markings which show that the angles are nearer one of the cardinal points than the other, so that a course may be marked off, by the compass, which, if followed for a certain time, and the speed of that period determined, can be traced and thus marked out on paper so that the outline of the coast can thereby be laid out.



The Professor had the charting board before him. "I have marked our starting point, which is designated as A. It will be remembered that we marked a course due west, passing the headland three miles from Cataract River. This is line 1. When we saw the land ahead of us last night, we changed our course by the compass to northwest, thus making a new line of travel, which you see is designated as 2. B was the point where the turn was made."



"But in what manner did you know how to transfer it to the board?"

"The board has two lines crossing each other at right angles to correspond with the two lines on the compass. The compass was put on the middle of the board, and the upper board turned so that the needle was on a line with the N——S line."

The boys now noticed for the first time that there were two boards, one above the other, and that the lower one was a little larger, and was attached to the boat. "Why do you have the lower board attached to the boat and larger than the upper one?"

"The lower board has on it a section of the compass, and the upper end a pointer, as you notice, and the line T represents the boat's direction, so that when the compass was placed on the upper board, the latter was turned so that it corresponded with the points of the compass. The little pointer then accurately pointed to northwest, on the lower board, and by this means the changing of the upper board, so as to keep it due east and west at all times, will enable us to keep on our course."

It was a long and weary night. One of them slept while the others were on duty. The boys knew the time on shipboard, where the day begins at midnight, and is divided into watches of four hours each, thus making three watches for the night and three for the day. A bell is struck every half hour, so that each watch is noted by the eight strokes of the bell. What is called the dog-watches occur between 4 and 8 P.M., this period being divided in the first dog-watch between 4 and 6, and the second dog-watch between 6 and 8.

"Why should such peculiar times be taken, or the periods be divided up in that way?"

"For the very reason that we discussed the arranging of our time of watch last night; namely, so that one person would not have the same watch every night. It was agreed by us that one should have three hours' uninterrupted sleep, while the others were on duty, so that each would in turn get three hours' work. Our arrangements are somewhat different from shipboard time, on account of our number, but the principle is the same."

During the night the wind changed to the north, so that progress was slow and required considerable tacking, and when the Professor came on duty he found the course still to the north, and on questioning Harry, found that the wind had been rather regular during his watch. Within a half hour of the time he took charge the western shore faded away, and the course was directed to NWW, in which direction they continued until well along in the forenoon. Then, as the land receded again, another tack was made, WbS, which means West by South.

The winds, however, were perverse during the second day. After a calm the wind veered to the west, and when in the afternoon the course was changed to SSW they had to sail close to the wind, and made slow progress.

Let us see what they found on the day's journey along the northern point which they rounded the second day of the journey. Cliffs, like their own, were distinctly visible in the evening and during the morning of the second day, but when morning broke on the third day they saw a beautiful shore line, and beyond the mountain range which was seen by them on their land trip to West River. It was now certain that the mouth of that river had been passed during the night and all regretted this.

During the whole of the third day they were forced to sail in the teeth of the wind, which necessitated frequent tacking. Not a sign of human habitation was seen on this day, but during the night, when the boys were on duty, they declared that they had seen lights to the south. The interest was most intense. Were they really rounding the island?

The course for the opening morning of the fourth day was SWbW, and early in the day they were not more than a mile from the shore, and then the shore gradually receded, but the course was not changed. The wind began to blow with greater force, and came from the southwest. As night approached it increased, but they continued tacking, hoping that they might reach the western extremity, and thus be able to run to the east before the wind.

Before eight o'clock lights were distinctly visible. They had reached the vicinity of human habitations. The boys were too excited to think of the watches which had thus far been observed. Aside from that, the wind had now reached such a violent stage that it was impossible to make any headway against it.

A consultation was had. "We must either turn to the north or go to shore. I fear this sudden change in the direction of the wind," was the Professor's opinion of the situation. It would not be wise to risk the shore. All knew that and sadly they turned the craft to the north. It was well that they did so. Every moment, it seemed, some new impetus would be given the wind. It howled on every side of them; the waves drifted across the little ship, until everything was dripping with moisture, and the only dry spot was within the little housed enclosure which had been well protected on the open rear side, thanks to the watchful suggestions of the Professor.

To add to their discomfort of mind, the land was not in sight. There was nothing to steer by except the compass and the chart which had been laid out. They were now going north over the course that had been traversed for the past two days—the west coast of the island.

It was a long, long night. No one slept, because fear and anxiety was ever with them. They remembered now with vividness the days spent on the ocean when they were wrecked. It was a terrible succession of hours, with the wind and the lightning and the rain one continuous orgy. The Professor sat at the tiller. The sails had been taken down long before. The impact of the driving storm against the housed structure was sufficient to drive it forward, so that the vessel could be guided.

It seemed that every blow against the boat would wrench it to atoms, but if any part had given way it was not apparent. Harry, who sat nearest the housed structure, suddenly sprang up, and pointing down, cried out: "It is leaking; look how it boils!" It was forethought on the part of the Professor to put in a supply of the oakum used for caulking purposes. Harry sprang for it, and George grasped the bailing pan. After a struggle a sufficient amount was driven into interstices to keep out at least a portion of the seepage. This knowledge was most oppressive. When a boat of this kind once springs a leak, due to a severe wrench of the shell itself, it is a difficult matter to remedy it, without structurally strengthening it.