The Wonder Island Boys: The Mysteries of the Caverns Part 5

"You may have heard of the monsoons, a periodical wind in the Indian Ocean, which is a northeast wind, and they blow with greater or less force from November to March."

"What causes them to blow with such regularity during those periods?"

"Ah! that is one of the things which it has been difficult to determine.

They appear to be modifications of the trade winds. While, as stated, the northeast winds blow during the periods mentioned, they have the southwest monsoons, which blow from April to October. As these violent winds are the most tempestuous during the period when the sun crosses the equator, it has been argued that it is due to the action of the sun being in such a position that its rays strike the earth in the center of its rotation, thus heating up the air and causing it to rise rapidly along the middle belt."

"Is that what we understand by the equinoctial storms?"

"The equinoctial storms come in March and September, when the days and nights are of equal length."

"I was told by a teacher that the summers are longer north of the equator than south of it; is that true?"

"Yes; the summer north of the equator is about seven and a half days longer."

"What is the cause of that?"

"The earth is at its greatest distance from the sun during the summer months, and the angular motion of the earth in its...o...b..t is slower. The result is, that the interval from the March to the September equinoxes is greater than from September to March."

Harry made his way through the violent wind and rain to the boat shed.

He came back with a sorry-looking countenance. "I am afraid everything is soaked beyond recovery." He was almost on the verge of tears.

Before noon the rain abated somewhat, but the winds still blew strongly, and when they ventured out to take stock of their surroundings, George was the first to notice the disappearance of the flag on Observation Hill. Rus.h.i.+ng in to the Professor, he cried: "Our flag is gone."

Harry was at the boathouse, and when George went down to inform him of the new calamity, he was almost heart-broken. The Professor, however, was not in the least perturbed. He laughingly chided them and soon restored the boys to their usual gay and happy demeanor.

"Such little incidents as we have met with this morning only give us variety. We need something of this kind to add zest to life. Just imagine what life would be if everything turned out just as you wanted it or willed it? You would commit suicide within a week."

The boys smiled, but at the same time their eyelids did double duty in the blinking line for a little while.

George straightened himself out and looked up the hill. "Well, I am going for that flag whether it blows or not," and he started for the hill. Angel, who was in the loft, swung down and made his way out of the door, and before George had gone fifty feet, was at his heels. "And you are going, too? Good boy!" and George actually hugged Angel. He understood.

Arriving at the hill he made an examination, and found that the halliards had been broken and the wind carried away the flag, halliards and all. As the wind came from the sea, the flag must be inland somewhere. Search was made in every direction, but to no purpose. Every rock and lodging place was examined, but it had disappeared. Angel was an interested searcher. He really seemed to divine George's mission. At every bush, or rock, or other possible landing place, he would be the first, and peer around, and look up and down, just as he had seen George do.

The quest kept up for over an hour, and, sadly disappointed, he returned with the news of his failure. The Professor took the loss lightly. "I presume it is intended that we should work out our own rescue. After all, I think that is the proper thing to do. If we depend on others we are sure to meet with disappointment and failure. Cheer up, boys; flag or no flag, let us do our duty."

"I don't mind the loss of the flag so much because it prevents us from having a signal, but I hate to think that we lost so much good time in making and putting it up."

The flag alluded to was sixteen feet long, laboriously made out of ramie fiber, which was woven, and then dyed, and it was a hard task to haul the pole, which was over fifty feet long, from the forest ten miles away, to say nothing of the labor required to raise it.

As soon as the thoroughly drenched material at the boathouse could be brought out and dried in the sun, which now came out bright and warm, the work proceeded with renewed vigor. Late that evening the Professor appeared at the rear of the laboratory, and called loudly to the boys.

When they appeared at the laboratory he was laughing immoderately, and Angel stood on one of the tables with a simian grin.

"What is the matter? Has Angel been experimenting again?"

Before the Professor could answer, George caught sight of the flag.

"What! The flag! Where did you get it?"

"Ask Angel."

The boys laughed, and George actually hugged the animal, in his delight.

Did Angel know what he had done? Ask those delvers into the mysterious realms of thought, what prompted him to search for and restore the flag?

Is that any more remarkable than the recorded tricks of dogs and many other animals?

You know just how boys can laugh when they are really happy. Angel imitated that laugh, and he had not been taught to do it, either. It came without teaching.

When the Professor had wiped away some of the tears which had come from the excess of laughter at the imitating efforts of the animal, he said:

"Did it ever occur to you why Angel has always had a solemn look? The facial expression seldom, if ever, changes, and they rarely ever exhibit mirth. You may imagine the condition of those animals, living in the forests, with enemies all about them, and the struggle for existence an everlasting one. They have never known amusing incidents as we understand them. Naturally, the muscles of mobility in the face, which express pleasure, never have been exercised, and those indicating fear and anger unduly developed. Here is Angel, in a new atmosphere, where he sees delight depicted on the countenance, and, gifted as he is, with wonderful powers of imitation, has learned to actually laugh, and to enjoy the scene."

"Well, Professor, as we have one of the guns polished up and completed, wouldn't it be well to make the bullets?"

"For that purpose I suggest that we make the molds out of a metal or alloy which has a higher fusing point than lead."

"What is best for the purpose?"

"We might make an alloy of copper and zinc."

"Oh! You mean bra.s.s?"

"Yes; that is readily cast and easily worked."

"But what shape shall we make the bullets?"

"They should be made long, with a pointed forward end."

"Why is a long bullet better than a round or globe-shaped ball?"

"There are several very important reasons. First, momentum is a prime element in a missile. A long one contains double the metal of a spherical one. Second, it can be made so that it will expand when the explosion of the powder takes place."

"In what way does it expand?"

"You have noticed that the rear end of the bullet has a cavity. When the explosion takes place the thin sh.e.l.l at the rear end of the bullet expands, so that it tightly hugs the bore of the gun."

"What is the object of having it do that?"

"To give the ball the benefit of the charge of powder exploded. If it does not fit tightly in the bore, more or less of the powder will pa.s.s the ball, and thus the ball loses part of its force."

"What is the object of rifling the gun?"

"The object is to impart to the bullet a spiral motion, as it moves through the air. Metals have not the same density on all sides and this is particularly true of molded b.a.l.l.s. As a result, when projected from the gun, the heaviest side has a tendency to divert the ball and make it more or less erratic in its motion, and, therefore, inaccurate. The spiral motion has the effect of minimizing this difficulty. The cavity formed at the rear of the projectile was devised particularly to cause the thin lip of the bullet to be driven into the grooves formed in the gun barrel, and by that means the boring motion was transmitted to the bullet."

"But as we have no means of rifling our guns, there will be no necessity of putting the cavity in the rear end of our bullets."

"We must have the cavity there, by all means."

"What for?"