"But then you could see nothing, make no geographical observations, or reconnoitre the face of the country."

"Ah!" replied the doctor, "if I am master of my balloon-if I can ascend and descend at will, I shall stop when I please, especially when too violent currents of air threaten to carry me out of my way with them."

"And you will encounter such," said Captain Bennet. "There are tornadoes that sweep at the rate of more than two hundred and forty miles per hour."

"You see, then, that with such speed as that, we could cross Africa in twelve hours. One would rise at Zanzibar, and go to bed at St. Louis!"

"But," rejoined the officer, "could any balloon withstand the wear and tear of such velocity?"

"It has happened before," replied Ferguson.

"And the balloon withstood it?"

"Perfectly well. It was at the time of the coronation of Napoleon, in 1804. The aeronaut, Gernerin, sent up a balloon at Paris, about eleven o'clock in the evening. It bore the following inscription, in letters of gold: 'Paris, 25 Frimaire; year XIII; Coronation of the Emperor Napoleon by his Holiness, Pius VII.' On the next morning, the inhabitants of Rome saw the same balloon soaring above the Vatican, whence it crossed the Campagna, and finally fluttered down into the lake of Bracciano. So you see, gentlemen, that a balloon can resist such velocities."

"A balloon-that might be; but a man?" insinuated Kennedy.

"Yes, a man, too!-for the balloon is always motionless with reference to the air that surrounds it. What moves is the ma.s.s of the atmosphere itself: for instance, one may light a taper in the car, and the flame will not even waver. An aeronaut in Garnerin's balloon would not have suffered in the least from the speed. But then I have no occasion to attempt such velocity; and if I can anchor to some tree, or some favorable inequality of the ground, at night, I shall not fail to do so. Besides, we take provision for two months with us, after all; and there is nothing to prevent our skilful huntsman here from furnishing game in abundance when we come to alight."

"Ah! Mr. Kennedy," said a young midshipman, with envious eyes, "what splendid shots you'll have!"

"Without counting," said another, "that you'll have the glory as well as the sport!"

"Gentlemen," replied the hunter, stammering with confusion, "I greatly-appreciate-your compliments-but they-don't-belong to me."

"You!" exclaimed every body, "don't you intend to go?"

"I am not going!"

"You won't accompany Dr. Ferguson?"

"Not only shall I not accompany him, but I am here so as to be present at the last moment to prevent his going."

Every eye was now turned to the doctor.

"Never mind him!" said the latter, calmly. "This is a matter that we can't argue with him. At heart he knows perfectly well that he IS going."

"By Saint Andrew!" said Kennedy, "I swear-"

"Swear to nothing, friend d.i.c.k; you have been ganged and weighed-you and your powder, your guns, and your bullets; so don't let us say anything more about it."

And, in fact, from that day until the arrival at Zanzibar, d.i.c.k never opened his mouth. He talked neither about that nor about anything else. He kept absolutely silent.

CHAPTER NINTH.

They double the Cape.-The Forecastle.-A Course of Cosmography by Professor Joe.-Concerning the Method of guiding Balloons.-How to seek out Atmospheric Currents.-Eureka.

The Resolute plunged along rapidly toward the Cape of Good Hope, the weather continuing fine, although the sea ran heavier.

On the 30th of March, twenty-seven days after the departure from London, the Table Mountain loomed up on the horizon. Cape City lying at the foot of an amphitheatre of hills, could be distinguished through the ship's gla.s.ses, and soon the Resolute cast anchor in the port. But the captain touched there only to replenish his coal bunkers, and that was but a day's job. On the morrow, he steered away to the south'ard, so as to double the southernmost point of Africa, and enter the Mozambique Channel.

This was not Joe's first sea-voyage, and so, for his part, he soon found himself at home on board; every body liked him for his frankness and good-humor. A considerable share of his master's renown was reflected upon him. He was listened to as an oracle, and he made no more mistakes than the next one.

So, while the doctor was pursuing his descriptive course of lecturing in the officers' mess, Joe reigned supreme on the forecastle, holding forth in his own peculiar manner, and making history to suit himself-a style of procedure pursued, by the way, by the greatest historians of all ages and nations.

The topic of discourse was, naturally, the aerial voyage. Joe had experienced some trouble in getting the rebellious spirits to believe in it; but, once accepted by them, nothing connected with it was any longer an impossibility to the imaginations of the seamen stimulated by Joe's harangues.

Our dazzling narrator persuaded his hearers that, after this trip, many others still more wonderful would be undertaken. In fact, it was to be but the first of a long series of superhuman expeditions.

"You see, my friends, when a man has had a taste of that kind of travelling, he can't get along afterward with any other; so, on our next expedition, instead of going off to one side, we'll go right ahead, going up, too, all the time."

"Humph! then you'll go to the moon!" said one of the crowd, with a stare of amazement.

"To the moon!" exclaimed Joe, "To the moon! pooh! that's too common. Every body might go to the moon, that way. Besides, there's no water there, and you have to carry such a lot of it along with you. Then you have to take air along in bottles, so as to breathe."

"Ay! ay! that's all right! But can a man get a drop of the real stuff there?" said a sailor who liked his toddy.

"Not a drop!" was Joe's answer. "No! old fellow, not in the moon. But we're going to skip round among those little twinklers up there-the stars-and the splendid planets that my old man so often talks about. For instance, we'll commence with Saturn-"

"That one with the ring?" asked the boatswain.

"Yes! the wedding-ring-only no one knows what's become of his wife!"

"What? will you go so high up as that?" said one of the ship-boys, gaping with wonder. "Why, your master must be Old Nick himself."

"Oh! no, he's too good for that."

"But, after Saturn-what then?" was the next inquiry of his impatient audience.

"After Saturn? Well, we'll visit Jupiter. A funny place that is, too, where the days are only nine hours and a half long-a good thing for the lazy fellows-and the years, would you believe it-last twelve of ours, which is fine for folks who have only six months to live. They get off a little longer by that."

"Twelve years!" e.j.a.c.u.l.a.t.ed the boy.

"Yes, my youngster; so that in that country you'd be toddling after your mammy yet, and that old chap yonder, who looks about fifty, would only be a little shaver of four and a half."

"Blazes! that's a good 'un!" shouted the whole forecastle together.

"Solemn truth!" said Joe, stoutly.

"But what can you expect? When people will stay in this world, they learn nothing and keep as ignorant as bears. But just come along to Jupiter and you'll see. But they have to look out up there, for he's got satellites that are not just the easiest things to pa.s.s."

All the men laughed, but they more than half believed him. Then he went on to talk about Neptune, where seafaring men get a jovial reception, and Mars, where the military get the best of the sidewalk to such an extent that folks can hardly stand it. Finally, he drew them a heavenly picture of the delights of Venus.

"And when we get back from that expedition," said the indefatigable narrator, "they'll decorate us with the Southern Cross that shines up there in the Creator's b.u.t.ton-hole."

"Ay, and you'd have well earned it!" said the sailors.

Thus pa.s.sed the long evenings on the forecastle in merry chat, and during the same time the doctor went on with his instructive discourses.

One day the conversation turned upon the means of directing balloons, and the doctor was asked his opinion about it.

"I don't think," said he, "that we shall succeed in finding out a system of directing them. I am familiar with all the plans attempted and proposed, and not one has succeeded, not one is practicable. You may readily understand that I have occupied my mind with this subject, which was, necessarily, so interesting to me, but I have not been able to solve the problem with the appliances now known to mechanical science. We would have to discover a motive power of extraordinary force, and almost impossible lightness of machinery. And, even then, we could not resist atmospheric currents of any considerable strength. Until now, the effort has been rather to direct the car than the balloon, and that has been one great error."

"Still there are many points of resemblance between a balloon and a ship which is directed at will."

"Not at all," retorted the doctor, "there is little or no similarity between the two cases. Air is infinitely less dense than water, in which the ship is only half submerged, while the whole bulk of a balloon is plunged in the atmosphere, and remains motionless with reference to the element that surrounds it."

"You think, then, that aerostatic science has said its last word?"

"Not at all! not at all! But we must look for another point in the case, and if we cannot manage to guide our balloon, we must, at least, try to keep it in favorable aerial currents. In proportion as we ascend, the latter become much more uniform and flow more constantly in one direction. They are no longer disturbed by the mountains and valleys that traverse the surface of the globe, and these, you know, are the chief cause of the variations of the wind and the inequality of their force. Therefore, these zones having been once determined, the balloon will merely have to be placed in the currents best adapted to its destination."

"But then," continued Captain Bennet, "in order to reach them, you must keep constantly ascending or descending. That is the real difficulty, doctor."

"And why, my dear captain?"

"Let us understand one another. It would be a difficulty and an obstacle only for long journeys, and not for short aerial excursions."

"And why so, if you please?"

"Because you can ascend only by throwing out ballast; you can descend only after letting off gas, and by these processes your ballast and your gas are soon exhausted."

"My dear sir, that's the whole question. There is the only difficulty that science need now seek to overcome. The problem is not how to guide the balloon, but how to take it up and down without expending the gas which is its strength, its life-blood, its soul, if I may use the expression."

"You are right, my dear doctor; but this problem is not yet solved; this means has not yet been discovered."

"I beg your pardon, it HAS been discovered."

"By whom?"

"By me!"

"By you?"

"You may readily believe that otherwise I should not have risked this expedition across Africa in a balloon. In twenty-four hours I should have been without gas!"

"But you said nothing about that in England?"

"No! I did not want to have myself overhauled in public. I saw no use in that. I made my preparatory experiments in secret and was satisfied. I have no occasion, then, to learn any thing more from them."

"Well! doctor, would it be proper to ask what is your secret?"

"Here it is, gentlemen-the simplest thing in the world!"

The attention of his auditory was now directed to the doctor in the utmost degree as he quietly proceeded with his explanation.

CHAPTER TENTH.

Former Experiments.-The Doctor's Five Receptacles.-The Gas Cylinder.-The Calorifere.-The System of Manoeuvring.-Success certain.

"The attempt has often been made, gentlemen," said the doctor, "to rise and descend at will, without losing ballast or gas from the balloon. A French aeronaut, M. Meunier, tried to accomplish this by compressing air in an inner receptacle. A Belgian, Dr. Van Hecke, by means of wings and paddles, obtained a vertical power that would have sufficed in most cases, but the practical results secured from these experiments have been insignificant.

"I therefore resolved to go about the thing more directly; so, at the start, I dispensed with ballast altogether, excepting as a provision for cases of special emergency, such as the breakage of my apparatus, or the necessity of ascending very suddenly, so as to avoid unforeseen obstacles.

"My means of ascent and descent consist simply in dilating or contracting the gas that is in the balloon by the application of different temperatures, and here is the method of obtaining that result.

"You saw me bring on board with the car several cases or receptacles, the use of which you may not have understood. They are five in number.

"The first contains about twenty-five gallons of water, to which I add a few drops of sulphuric acid, so as to augment its capacity as a conductor of electricity, and then I decompose it by means of a powerful Buntzen battery. Water, as you know, consists of two parts of hydrogen to one of oxygen gas.

"The latter, through the action of the battery, pa.s.ses at its positive pole into the second receptacle. A third receptacle, placed above the second one, and of double its capacity, receives the hydrogen pa.s.sing into it by the negative pole.

"Stopc.o.c.ks, of which one has an orifice twice the size of the other, communicate between these receptacles and a fourth one, which is called the mixture reservoir, since in it the two gases obtained by the decomposition of the water do really commingle. The capacity of this fourth tank is about forty-one cubic feet.

"On the upper part of this tank is a platinum tube provided with a stopc.o.c.k.

"You will now readily understand, gentlemen, the apparatus that I have described to you is really a gas cylinder and blow-pipe for oxygen and hydrogen, the heat of which exceeds that of a forge fire.

"This much established, I proceed to the second part of my apparatus. From the lowest part of my balloon, which is hermetically closed, issue two tubes a little distance apart. The one starts among the upper layers of the hydrogen gas, the other amid the lower layers.

"These two pipes are provided at intervals with strong jointings of india-rubber, which enable them to move in harmony with the oscillations of the balloon.

"Both of them run down as far as the car, and lose themselves in an iron receptacle of cylindrical form, which is called the heat-tank. The latter is closed at its two ends by two strong plates of the same metal.

"The pipe running from the lower part of the balloon runs into this cylindrical receptacle through the lower plate; it penetrates the latter and then takes the form of a helicoidal or screw-shaped spiral, the rings of which, rising one over the other, occupy nearly the whole of the height of the tank. Before again issuing from it, this spiral runs into a small cone with a concave base, that is turned downward in the shape of a spherical cap.

"It is from the top of this cone that the second pipe issues, and it runs, as I have said, into the upper beds of the balloon.

"The spherical cap of the small cone is of platinum, so as not to melt by the action of the cylinder and blow-pipe, for the latter are placed upon the bottom of the iron tank in the midst of the helicoidal spiral, and the extremity of their flame will slightly touch the cap in question.