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Chapter 23 Chapter 24 The Telescope in the Rocky Mountains

from earth to moon 儒勒·凡尔纳 2882Words 2018-03-23
After the fundraising ended on October 20 last year, the chairman of the Cannon Club allocated a sum of money to the Jianqiao Observatory to build a huge optical instrument. This instrument, whether it is a refracting telescope or a reflecting telescope, must be extremely powerful , to see clearly an object no more than nine feet in diameter on the lunar surface. There is one extremely important difference between these two telescopes which should be stated here.A refracting telescope has a long tube with a convex lens at the top, called the objective lens, and a lens at the bottom, called the eyepiece. The observer: the eye observes objects through this lens.The light emitted from the illuminant passes through the first lens, undergoes refraction, and forms an object image at the focal point.

The observer looks at the object image magnified by this lens from the eyepiece, just like observing the object with a magnifying glass.Therefore, the tube for dismantling the telescope is blocked by the objective lens at one end and the eyepiece at the other end. In contrast, the upper end of the reflecting telescope is open.The light of the observed object freely penetrates the nozzle and strikes a metal concave mirror, that is to say, the condenser.From there the light is reflected onto a small mirror, and then passed through the eyepiece to magnify the image. Therefore: the refracting telescope mainly uses the refraction effect, while the reflecting telescope uses the reflection effect, so the former is called a refracting mirror, and the latter is called a reflecting mirror. All the difficulties in making these optical instruments are concentrated in the objective lens, that is to say On convex lenses or metal reflectors.

However, in the era when the Gun Club carried out its great experiments, these instruments were already very sophisticated and achieved good results, and the era when Galileo observed celestial bodies with his demolition telescope that can only magnify seven times has become a distant past.Since the sixteenth century, optical instruments have become thicker, longer, and larger, making it possible for us to measure the unprecedented depth of constant space. The refracting telescope that was working at that time was the telescope of the Russian Bukova Observatory. There is the telescope of the French optician Rilbe, with an objective of the same size; and lastly, the telescope of the Cambridge Observatory, with an objective of nineteen inches in diameter.

Among the reflecting telescopes; we know of two powerful giant telescopes.The first, built by Herschel, was thirty-six feet long and contained a mirror four and a half feet wide, capable of magnifying six thousand times.The second towers over Pitsenton Park in Billcastle, Ireland, and belongs to Sir Lowes.The tube was forty-eight feet long, the reflector six feet wide, magnified six thousand four hundred times, and weighed twenty-eight thousand pounds. A large building had to be built to house the machinery for operating the instrument. "We could see that these instruments, though enormous, could only magnify about six thousand times; however, at six thousand times, the distance of the moon was reduced to only thirty-nine miles, and only objects sixty feet in diameter could be seen unless These objects are exceptionally long.

But now, the shell was only nine feet wide and fifteen feet long!It is therefore necessary to reduce the distance to the Moon to at least five miles, and to do this the telescope must be magnified by a factor of forty-eight thousand. This was the problem encountered by the Cambridge Observatory.They have no financial difficulties, only material difficulties. First of all, choose between a refracting telescope and a reflecting telescope.Refracting telescopes are better than reflecting telescopes.With the same size objective lens, it can magnify more times, because the loss of light passing through a convex lens is smaller than that passing through a metal mirror.But the thickness of the convex lens is limited, because if it is too thick, the light will not come in.On the other hand, building such a large lens is very difficult and takes a long time, often taking several years.

Objects, therefore, appear brighter in refracting telescopes, which is an inestimable advantage. Now the moon is being observed, and the moon is nothing but a reflective body. Nevertheless, it was decided to use reflecting telescopes, because the construction of such instruments It doesn't take much time and can increase the magnification factor at the same time.But the light loses a great deal of its intensity in passing through the atmosphere, and the Cannon Club decided to reduce the thickness of the air layer by locating its instruments on the highest mountain in the United States. We have mentioned above that the eyepiece of the reflecting telescope, that is, the lens placed under the observer's eyes, produces magnification, and the larger the diameter of the objective lens, the longer the focal length and the larger the magnified object image.To magnify forty-eight thousand times.

The objective lens must be several times larger than that of Herschel and Lord Ross.This is difficult because casting such a reflector is a very delicate job. Fortunately, a few years ago, Leon Focauau, a scientist at the French Academy, invented a new method to replace the metal mirror with a silver-plated mirror. In this way, the manufacture of the objective lens is fast and convenient.Just make a glass mirror the size you need and silver it.The Cambridge Observatory used this method with good effect to manufacture objectives. In addition, they used an installation devised by astronomer Herschel of Slough.Objects were reflected directly from an angled mirror at the bottom of his huge instrument tube into an eyepiece at the other end.Therefore, the observer's eyes are not from the bottom of the tube, but from the eyepiece on the top of the tube into this huge cylinder.The advantage of this combination is that it does away with the small mirror that reflects the image of the object into the eyepiece)

There is only one, not two, reflection procedures.Therefore, less light is lost, and the object image is not very blurred.In short, the light is more sufficient, which is a benefit worthy of attention for the current observations. With these few decisions taken, the work began.According to the calculations of the Cambridge Observatory Office, the length of the new telescope should be two hundred and eighty feet, and the diameter of the mirror should be sixteen feet.Although this instrument is large, it cannot be compared with the ten-mile-long reflecting telescope designed by the astronomer Hooke some years ago.Still, building such an instrument is difficult.

The foundation problem was solved neatly.A high mountain must be selected, but there are very few high mountains in Taiwan. Indeed, in this great country there are but two modest mountains, between which the beautiful Mississippi flows, and if the Americans allow any kingdom to exist they will call it the "King of the Rivers." The one running from east to west is the Appalachian Mountains. Its highest peak stands in New Hampshire and is less than 5,600 feet high. It is a very ordinary mountain. On the contrary, the Rocky Mountains in the west is a continuous mountain range, which rises from the Strait of Magellan, along the west coast of South America, called the Andes or the Cordinara Mountains, and passes through the Isthmus of Panama.Over North America, has been running to the coast of the Arctic Sea. "

These mountains are not very high, and the Alsaces or the Himalayas are afraid to look at them with great contempt from a height.To be honest, their tallest peak is only 10,701 feet, while Mont Blanc is 14,439 feet, and Kanchenjunga is 26,776 feet above sea level. . But, as in the case of the Columbia Cannon, the Cannon Club must have the telescope in the United States, and must be content with the Rocky Mountains.All necessary supplies were therefore transported to Lang Peak, Missouri. Neither pen nor language can do anything to describe how American engineers overcame various difficulties and accomplished miracles requiring skill and courage.This is a real showdown.They must leave the populated areas far away, walk into the wilderness where human beings can hardly survive, pass through uninhabited grasslands, impassable forests, cross terrible rapids, climb up snow-covered mountains all the year round, and throw large stones , heavy wrought iron, heavy iron corners, huge lens barrel parts, and objective lenses weighing 30,000 pounds were transported to a mountain as high as more than 10,000 feet.But at last American genius overcame hundreds of obstacles.Less than a year after work began, in late September the 280-foot-long tube of the gigantic reflecting telescope reached into the sky.It is suspended on a tall iron frame, and a set of exquisite mechanical equipment can be easily manipulated to make it point to any point in the sky, and make it follow the celestial body moving in the sky from the horizon of one side, and keep chasing it. to the other side of the horizon.

The telescope is worth over $400,000.When it aimed at the moon for the first time, observers were excited, curious, and uneasy.What will they find in the field of view of this 48,000-power telescope?Will you discover the inhabitants of the Moon, herds of animals, cities, lakes, oceans?No, what they saw was what the scientific community already knew. Every part of the lunar disc can prove absolutely correct that the Moon Mountains are volcanic in nature. But the telescope on the Rocky Mountains had already done a great deal for astronomy before the Cannon Club used it.Because of its powerful insight, the deepest part of the sky has been detected, and the apparent diameters of many stars have been measured. Mr. Clark of the Cambridge Observatory Office has determined the Cancer Nebula in Taurus. less than.
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