From the Earth to the Moon (22 page)

Air is composed, practically speaking, of twenty-one percent oxygen and seventy-nine percent nitrogen. What happens when we breathe? It is a simple phenomenon. We absorb oxygen, which is necessary for sustaining life, from the air, and expel the nitrogen intact. Exhaled air has lost nearly five percent of its oxygen and contains an almost equal volume of carbonic acid, the end product of the combustion of the elements of the blood by the inhaled oxygen. In a closed space, therefore, after a certain time all the oxygen in the air will be replaced by carbonic acid, which is an essentially noxious gas.

The question came down to this: with the nitrogen conserved intact, how could the oxygen be replenished and how could the carbonic acid be destroyed? It was quite easy, by means of potassium chlorate and caustic potash.

Potassium chlorate is a salt which exists in the form of white flakes. When it is heated to a temperature above four hundred degrees centigrade, it is transformed into potassium chloride, and the oxygen it contains is entirely given off. Eighteen pounds of potassium chlorate yields seven pounds of oxygen: the amount the passengers needed for twenty-four hours. So much for replenishing the oxygen.

As for caustic potash, it has a strong affinity for the carbonic acid mingled in the air. It need only be agitated in order to make it combine with the carbonic acid and form potassium bicarbonate. So much for absorbing the carbonic acid.

By combining these two processes, it was possible to restore all the life-giving properties to the exhaled air. The two chemists, Reiset and Regnault, had shown this experimentally. But it must be said that so far the experiment had been performed only with animals. However great its scientific precision, its effect on men was still completely unknown.

These were the facts that Michel Ardan pointed out during the meeting at which the important question was considered. Not wishing to leave any doubt about the possibility of living on that artificial air, he offered to try it himself before the departure. But the honor of making the test was energetically demanded by J. T. Maston.

“Since I’m not going with you,” he said, “the least you can do is to let me live in the projectile for a week or so.”

The others would have been unkind to refuse him. They granted his request. He was given enough food, water, potassium chlorate, and caustic potash for eight days; then on November 12, at six o’clock in the morning, after having shaken hands with his friends and expressly instructed them not to open his prison until six o’clock on
the evening of November 20, he slipped into the projectile and the opening was hermetically sealed behind him.

What happened inside the projectile during the eight days? It was impossible to tell. The thickness of its walls prevented all sounds from reaching the outside.

On November 20, at exactly six o’clock, the cover was removed from the opening. J. T. Maston’s friends were a little worried, but they were promptly reassured when they heard a loud, joyful “Hurrah!”

J. T. Maston soon appeared at the top of the cone in a triumphant pose. He had gained weight!

O
N OCTOBER
20 of the previous year, after the closing of the subscription, Barbicane had turned over to the Cambridge Observatory the money necessary for the construction of an enormous telescope. This telescope, whether a refracting or a reflecting one, was to be powerful enough to detect an object no more than nine feet wide on the surface of the moon.

There is an important difference between a refracting and a reflecting telescope; it will be best to recall it here. A refracting telescope is composed of a tube which has at its upper end a convex lens called the objective, and at its lower end a second lens known as the ocular, to which the observer applies his eye. Light rays from the object pass through the first lens and, by refraction, form an inverted image at its focus.
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This image is observed through the ocular, which enlarges it exactly like a magnifying glass. Thus the tube of a refracting telescope is closed at both ends by the objective and the ocular.

The reflecting telescope, on the other hand, is open at its upper end. Light rays from the observed object penetrate it freely and strike a concave, i.e., converging, metal mirror. From there they are reflected to a small mirror
that sends them to the ocular, which is so disposed as to magnify the image produced.

Thus in a refracting telescope it is refraction that plays the principal role, while in a reflecting telescope it is reflection. The former is sometimes called simply a refractor, the latter a reflector. The difficulty in making them lies almost entirely in making the objective, whether it be a lens or a metal mirror.

At the time when the Gun Club was preparing for its great experiment, these instruments had been highly perfected and gave magnificent results. Science had come a long way since the days when Galileo observed the heavenly bodies with his poor little seven-power refracting telescope. Since the sixteenth century, telescopes had grown considerably wider and longer, and had made it possible to probe more deeply into interstellar space. Among the refracting telescopes in operation at that time were the one at the Pulkovo Observatory in Russia, with a fifteen-inch objective;
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the one made by the French optician Lerebours, also with a fifteen-inch objective; and the one at the Cambridge Observatory, with a nineteen-inch objective.

Among the reflecting telescopes there were some of remarkable power and gigantic size. The first one, made by Herschel, had a length of thirty-six feet, a mirror with a diameter of four and a half feet, and a magnification of six thousand. The second one was in Birr, Ireland, and belonged to Lord Rosse. It was forty-eight feet long, its mirror was six feet in diameter,
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and its magnification was 6,400; an immense
stone structure had to be built to house the instruments for maneuvering it, and to support its weight of 28,000 pounds.

Despite these colossal dimensions, however, the magnification obtained never went very far beyond six thousand. A magnification of six thousand brings the moon to an apparent distance of thirty-nine miles and makes it possible to see objects with a width of no less than sixty feet, unless they are extremely long.

In order to see the Gun Club’s projectile, which was nine feet wide and fifteen feet long, the moon would have to be brought to an apparent distance of five miles or less, and this would require a magnification of 48,000.

Such was the problem faced by the Cambridge Observatory. It would not be stopped by financial difficulties, but there were still physical difficulties to be overcome.

First of all, a choice had to be made between a refractor and a reflector. Refractors have certain advantages over reflectors. With the same objective diameter they make it possible to obtain greater magnification, because light rays passing through the lenses lose less by absorption than by reflection from the metal mirror of a reflector. But the thickness that can be given to a lens is limited: if the lens is too thick, it will not let light rays pass through it. Furthermore, the construction of such enormous lenses is difficult and the time is measured in years.

Therefore, even though the images are illuminated better in a refractor—an appreciable advantage in observing the moon, whose light is simply reflected—it was decided to use a reflector, which can be made more quickly and permits greater magnification. And since
light rays lose a great deal of their intensity in passing through the earth’s atmosphere, the Gun Club decided to put the telescope on one of the highest mountains in the country, which would diminish the amount of air that would have to be traversed by the light.

As we have seen, in a reflecting telescope the ocular—that is, the magnifying glass placed before the observer’s eye—produces the magnification, and the greater the diameter and focal distance of the objective, the greater the magnification it will allow. To obtain a magnification of 48,000, the size of Herschel’s and Lord Rosse’s objectives would have to be far surpassed. There lay the difficulty, for the casting of such mirrors is a very delicate operation.

Fortunately a few years earlier a scientist at the Institut de France, Léon Foucault, had invented a way of greatly reducing the time required for polishing an objective by replacing metal mirrors with silvered glass ones. One had only to cast a piece of glass to the right size, then plate it with silver. This process, which gives excellent results, was used in making the objective.

It was arranged in accordance with Herschel’s method. In his big telescope, the image of the object, reflected by the inclined mirror at one end of the tube, was formed at its other end, where the ocular was situated. Thus the observer, instead of being placed at the lower end of the tube, raised himself to its upper end, and there, with his magnifying glass, he looked into the enormous cylinder. This system had the advantage of eliminating the little mirror whose function was to reflect the image to the ocular, so the image was reflected only once instead of twice. Therefore fewer light rays were absorbed, the image was less weakened, and
greater brightness was obtained.
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This would be a valuable advantage in observing the projectile.

When these decisions had been made, the work was begun. According to the Cambridge Observatory’s calculations, the new telescope would have to be 280 feet long, and its mirror would have to have a diameter of sixteen feet. However colossal it might be, it would not be comparable to the 10,000-foot telescope that the astronomer Hooke proposed building several years ago. Nevertheless its construction presented great difficulties.

As for the question of location, it was quickly settled. A high mountain had to be chosen, and high mountains are not numerous in the United States.

The mountains of that great country are composed of two ranges of medium height. Between them flows the magnificent Mississippi, which the Americans would call “the king of rivers” if they were willing to accept any kind of royalty.

In the east are the Appalachians, whose tallest peak, in New Hampshire, is 6,600 feet high, which is quite modest.

In the west are the Rocky Mountains, an immense range which begins at the Straits of Magellan, runs along the west coast of South America under the name of the Andes, crosses the Isthmus of Panama, and extends across North America all the way to the Arctic.

These mountains are not very high; the Alps or the Himalayas would look down on them from their lofty heights. Their tallest peak is only 11,771 feet high, whereas Mont Blanc is 15,787 feet high, and Kinchinjunga, the
highest of the Himalayas, rises 29,454 feet above sea level.

But since the members of the Gun Club wanted the telescope as well as the cannon to be within the boundaries of the United States, they had to content themselves with the Rocky Mountains. All the necessary materials and equipment were sent to Longs Peak, in Colorado Territory.

The difficulties of all kinds that the American engineers had to overcome, and the wonders of daring and skill that they accomplished, could not be described by tongue or pen. It was a truly spectacular feat. Huge stones, heavy forged parts, enormous pieces of the cylinder, and the objective, with a weight of 30,000 pounds, had to be brought up above the snow line, over 10,000 feet high, after having been brought across deserted prairies and through dense forests and fearful rapids, far from all centers of population, in wild regions where each detail of life became an almost insoluble problem. But the Americans’ genius triumphed over these countless obstacles. In late September, less than a year after work had begun, the gigantic tube of the telescope, 284 feet long, was pointing into the air. It was suspended from an enormous iron framework; an ingenious mechanism enabled the observer to aim it at any point in the sky and follow the heavenly bodies from one horizon to the other as they moved through space.

It has cost more than $400,000. The first time it was aimed at the moon, the observers were both curious and apprehensive. What were they going to discover in the field of that 48,000-power telescope? Populations, herds of lunar animals, cities, lakes, oceans? No, they saw nothing that science had not known already. They were, however,
able to determine the moon’s volcanic nature with absolute precision.

Before serving the Gun Club, the Longs Peak telescope rendered immense services to astronomy. With its great power, it was able to scan the outermost reaches of the heavens; the apparent diameters of stars were rigorously measured, and Mr. Clarke of the Cambridge Observatory decomposed the crab nebula in Taurus, which Lord Rosse’s telescope had never been able to resolve.