Telescope

“ By its aid we obtain a sensible demonstration that space is boundless—that the universe is replenished with innumerable suns and worlds—that the remotest regions of immensity, immeasurably beyond the limits of unassisted vision, display the energies of Creating Power, and that the Empire of the Creator extends far beyond what eye hath seen or the human imagination can conceive.
The telescope is an instrument of a much more wonderful nature than what most people are apt to imagine. ”

“ Beyond the stars which we can see with the naked eye, the telescope unfolds to the view thousands upon thousands of others, the very existence of which we had never known but for this instrument. Nor is even this all—​some of the stars are not single, but two or three are close together, and evidently revolve around one another. ”

“ I am sure there is not a single boy or girl who would trade off one of these perfect little telescopes—yes, I will call it a telescope and an observatory also—for God has beautifully encased our eyes, and shielded and housed them more beautifully and satisfactorily than the most perfect observatory which was ever built for any man-made telescope. We would not trade away one of our eyes for one of the finest telescopes in the world, and we would not be willing to give both of our eyes for all the telescopes which have ever been made. ”

“ There is a great charm in watching this pair of stars even with a three-inch telescope—not so much on account of what is seen, although they are very beautiful, as on account of what we know they are doing. It is no slight thing to behold two distant stars obeying the law that makes a stone fall to the ground and compels the earth to swing round the sun. ”

“ The most powerful telescope in existence is that existing telescope which can do the most work. The work of a telescope may be said to be to enable you to see and to enable you to measure. Therefore, that telescope with which you can see most and can measure best is that which can do the most work, and is unquestionably the most powerful telescope in existence. ”

“ The telescope is an optical instrument for viewing objects at a distance. Its name is compounded of two Greek words,—τηλε, which signifies, at a distance, or far off, and σχοπειν, to view, or to contemplate. By means of telescopes, remote objects are represented as if they were near, small apparent magnitudes are enlarged, confused objects are rendered distinct, and the invisible and obscure parts of very distant scenes are rendered perceptible and clear to the organ of vision. The telescope is justly considered as a grand and noble instrument. ”

“ Yet when we come to consider what it really is which is described as being seen, when we calmly examine the various drawings which have been made by the aid of one or the other of these great telescopes, then we find that they show nothing which can not be distinctly seen and drawn by the smallest astronomical telescope of high excellence. An enormous blaze of light is gathered by the telescopes, but all this light reveals nothing which can not be seen with far greater ease in a far smaller telescope. ”

“ The telescope has discovered stars hitherto unknown and inaccessible to all our means of mensuration; it has penetrated distances so great, that luminous and necessarily immense bodies present themselves to us only like nebulous and almost imperceptible spots. ”

“ If the air is not reasonably steady we had better postpone our experiment to another night, because we shall find that the star as seen in the telescope flickers and "boils," and behaves in so extraordinary a fashion that there is no more definition in the image than there is steadiness in a bluebottle buzzing on a window pane. ”

“ A small telescope will perform very well on a night when a large one is helpless.
Turn the glass upon β (Rigel) , the white first-magnitude star in Orion's left foot. Observe whether the image with a high power is clear, sharp, and free from irregular wisps of stray light. Look at the rings in and out of focus, and if you are satisfied with the performance, try for the companion. A good three-inch is certain to show it, except in a bad state of the atmosphere, and even then an expert can see it, at least by glimpses. ”

“ But the Finder, which is a telescope with a small power, and consequently has a large field of view—when directed to any object, it is easily found, and being brought to the centre of the field, where two cross hairs intersect each other, it will then be seen in the larger telescope. B is the eye-tube for terrestrial objects, containing 4 glasses, and C, one of the astronomical eye-pieces. A socket is represented at g, containing a stained glass, which is screwed to any of the eye-pieces, to protect the eye from the glare of light, when viewing the spots of the sun. ”

“ A rival method to that of the heliometer has been discovered in the photographic telescope. The plan of this instrument, and its application to such purposes as this, are extremely simple. We point a telescope at a star and set the clock-work going, so that the telescope shall remain pointed as exactly as possible in the direction of the star. We place a sensitized plate in the focus and leave it long enough to form an image both of the particular star in view and of all the stars around it. ”

“ Our star map No. 1 will serve as a guide to the objects which we are about to inspect. Let us begin operations with our smallest telescope, the three-inch. I may remark here that, just as the lowest magnifying power that will clearly reveal the object looked for gives ordinarily better results than a higher power, so the smallest telescope that is competent to show what one wishes to see is likely to yield more satisfaction, as far as that particular object is concerned, than a larger glass. The larger the object glass and the higher the power, the greater are the atmospheric difficulties. ”

“ You need not, however, wait for an opportunity to look through giant telescopes, for my small student's telescope, only four feet long, which we carry out on to the lawn, will show you endless unseen wonders; while your hand telescopes, and even a common opera-glass, will show many features on the face of the moon, and enable you to see the crescent of Venus, Jupiter's moons, and Saturn's rings, besides hundreds of stars unseen by the naked eye. ”

“ There are hundreds of things continually referred to in books and writings on astronomy which have but a misty and uncertain significance for the mere reader, but which he can easily verify for himself with the aid of a telescope of four or five inches aperture, and which, when actually confronted by the senses, assume a meaning, a beauty, and an importance that would otherwise entirely have escaped him. ”

“ Assuming that we have a telescope in which no obvious fault is discernible, the next thing is to test its powers in actual work. In what is to follow I shall endeavor to describe some of the principal objects in the heavens from which the amateur observer may expect to derive pleasure and instruction, and which may at the same time [Pg 18] serve as tests of the excellence of his telescope. No one should be deterred or discouraged in the study of celestial objects by the apparent insignificance of his means of observation. ”

“ The observation of spots on the Sun by projecting 27 them on to a white paper screen with the aid of a telescope is a method so convenient and so exact as to deserve a detailed description, the more so as it is so little used. Let there be made in the shutter of a darkened room a hole so much larger than the diameter of the telescope to be used as will allow a certain amount of play to the telescope tube, backwards and forwards, up and down, and from right to left. ”

“ As the telescope can be raised or depressed so as to be directed to any elevation from the horizon to the zenith, and turned around the entire circle with the dome, it can be pointed to any part of the heavens. But as the star or other celestial object is always apparently moving, in consequence of the real rotatory movement of the earth, the telescope is made to follow it automatically by an ingenious clock-work arrangement. No place, short of the temple of the living God, can be more solemn. ”

“ One position which very naturally occurs to us is the horizontal one. If we lay the big telescope on the ground, there is no danger of its falling: and it is in other respects convenient to work with. Hence several large telescopes have already been built in this way. A good example is the Snow telescope on Mount Wilson. You see in the picture the long shed which is really the telescope itself: and at one end there is the coelostat mirror, reflecting the light (in this case usually the light of the Sun, not that of a star) into the telescope. ”

“ If the pure and elevated pleasure to be derived from the possession and use of a good telescope of three, four, five, or six inches aperture were generally known, I am certain that no instrument of science would be more commonly found in the homes of intelligent people. ”

“ The telescope may be pointed at the horizon, for example, directly under the position of the sun, and the arm of the instrument, altering the position of the so-called index mirror, may be rotated until the limb of the sun seems just to touch the horizon—the latter being viewed through the unsilvered half of the horizon glass. ”

“ When the telescope is moved into any position the lamp swings like a mariner’s compass on its gimbals, and still throws its light into the tube, and the light mixes up with that coming from the star, but spreads all over the field of 326view instead of coming to a point, so that the star is seen on a bright field, and the wires as black lines. ”

“ The telescope is directed to any one star, and then by turning the instrument round the axis, it is found, that without any alteration in the position of the telescope in relation to the axis, the telescope will follow the star from its rising to its setting. ”

“ There are usually many different eyepieces for a telescope, and they contain lenses of varied powers, to be used according to the state of the atmosphere, or to the particular kinds of observation in progress.
If you point a big telescope to the sky, and see therein the sun or the moon or any of the stars, you will speedily find that the objects pass away out of view. Remember our earth is constantly turning round, and bears, of course, the Observatory with it, so that though the telescope be rightly pointed to the heavens at one moment, by the next it will have been98 turned aside. ”

“ The astronomer will not be contented with a mere naked-eye inspection of a world so interesting as the moon. He will get a telescope to help his vision. The word “telescope” means a contrivance for looking at objects which are a long way off. We have explained that the further an object is, the smaller it appears to be. The telescope enables us to largely overcome this inconvenience. It has the effect of making a distant object look larger. ”

“ With a well mounted telescope of either sort a star at fair altitude on a fine night gives even better testing conditions than an artificial star, (Polaris is good in northern latitudes) but one may have a long wait.
If the reflector is of good figure and well adjusted, the star image, in focus or out, has quite the same appearance as in a refractor except that with a bright star in focus one sees a thin sharp cross of light centered on the image, rather faint but perfectly distinct. ”

“ In consequence of the thinness of the rings they completely disappear from the range of vision of small telescopes when, as occurs once in every fifteen years, they are seen exactly edgewise from the earth. In a telescope powerful enough to reveal them when in that situation they resemble a thin, glowing needle run through the ball of the planet. ”

“ You may know something of the witchery of the heavens even with a little telescope of three to five inches aperture!" "Pleasures of the Telescope" is popular in style rather than technical. For setting forth "the chief attractions of the starry heavens," a complete set of star-maps is included, showing "all the stars visible to the naked eye in the regions of sky represented, and in addition some stars that can only be seen with optical aid." ”

“ By setting the telescope to read an angle of forty-five degrees and snapping a stop watch on an object which lies in the line of sight of the telescope produced, and then swinging the telescope so as to point vertically downward, we can, by snapping the stop watch a second time as the sighting point again comes into the field of vision, ascertain the exact time it has taken the machine to cover the distance measured by forty-five degrees of arc. ”

“ The telescope resolves them into millions of suns, standing out from the oceans of white-hot matter that contain the germs of countless systems yet to be. And so far removed from us are these suns that the light which comes to us from them to-day has been speeding on its way for more than two million years. ”

“ Without a telescope the small stars which accompany double or treble stars cannot be perceived, and much less their motions or variation of their relative positions. Before the invention of the telescope such phenomena—now deemed so wonderful and interesting—could never have been surmised. 5. The accurate determination of the longitude of places on the earth’s surface is ascertained by the telescope, by observing with this instrument the immersions and emersions of the satellites of Jupiter. ”

“ As the powers of the telescope were gradually developed, it was found that the finest hairs or filaments of silk, or the thinnest silver wires that could be drawn, were much too thick for the refined purposes of the astronomer, as they entirely obliterated the image of a star in the more powerful telescopes. ”

“ With a telescope armed with a medium power, the field of view of which is more extensive than that of a high power, we find that if a light tap is given to the telescope, the ordinary simple image is changed into a luminous curve, the perimeter of which is formed entirely of a succession of arcs exhibiting the colours of the rainbow. ”