Lumen

“ The sun is the great lamp that illuminates the world, while the atmosphere, which is filled with particles of various substances, becomes the shade of the lamp which diffuses and softens the light and gives it its color tones, whether of warmth or coldness. We could not well do without the reflected light of the sky. The poetry of life would be sadly marred. The beautiful effects of color and purity of tone would be wanting. We need to bathe in light as much as in water, and the character of the light is almost as important as the character of the water. ”

“ As you approach, the brilliancy of the star declines; and when the full flood of light is thrown upon the shell, it nearly, or entirely disappears. If you press your finger rudely upon the spot, you will again perceive the luminous matter diffused, like a fluid, over the surrounding surface, and shining, for an instant, more brightly than ever, even under the immediate glare of the gas. ”

“ That which before lay buried in the shade of night is itself now a radiator of the luminous fluid. Mark the genial warmth that comes as the sister of light; then stand by the side of the experimentalist and watch the point on which he directs the shining focus, and in an instant see iron melt and stones run like water, under the fervent heat! Now look upward to the heavens, where the falling drops of rain have formed a natural prism in the rainbow, and shown that the beam of pure whiteness, refracted into various rays, glows with all the tints that adorn the garden of nature. ”

“ On gazing down into its depths, when not a breath of wind sweeps over its surface, when its face is like a polished mirror, we find the water almost as transparent as the air we breathe, yet the keenest optics can penetrate but a few fathoms below the surface. ”

“ But if we clear the air of dust, as I now do by burning it with a spirit-lamp placed underneath, the beam disappears from the parts so cleared, and the space becomes dark. If, therefore, the air were absolutely pure and devoid of matter foreign to it, the azure of the sky would be no longer seen, and the heavens would appear black; the illumination of objects would be strong and glaring on the one side, and on the other their shadows would be deep, and unrelieved by the diffused light to which we are accustomed. ”

“ Nothing dispelled that darkness but the dim starlight from above, but now, as we gazed forth, we became aware of a faint light coming feebly toward us from far ahead, a faint light that seemed like a great, feebly-glowing cloud in the darkness, and that was intensifying in radiance with each moment that we rushed toward it. ”

“ Any thing white seen in a dense air full of vapours, will appear larger than it is in reality.
The air, between the eye and the object seen, will change the colour of that object into its own; so will the azure of the air change the distant mountains into blue masses. Through a red glass every thing appears red; the light round the stars is dimmed by the darkness of the air, which fills the space between the eye and the planets. ”

“ These nerve vibrations are sent over the optic nerve to the brain, where they take on the shape, size and colors of the Sun.
Reflection of Light.—The flame of a match, or a candle, an oil or a gas lamp, or Sun, comet or meteor, produces its own light, and for this reason these bodies are called self-luminous—that is, they are themselves the source of light.
All other objects which do not produce light, such as an apple, a stone, the Earth and other planets and moons are called non-luminous bodies. ”

“ Through the agency of light, a subtle, intangible, imponderable something, originating, apparently, in the stars and suns, darting with incredible velocity from one quarter of the universe to the other, whether in absolute particles of matter shot off from luminous bodies, or by traces of an ethereal fluid, who shall tell? This incomprehensible fluid falls upon an instrument of most insignificant dimensions, yet of most wonderful construction, the human eye, and, lo! to the mind what wonders start into being. ”

“ Usually the sky seems a flat or a dome-shaped sheet of colour over us, to-night it was a solid vapoury mass of quivering blue particles—indescribable, but thrilling as an electric shock, and as unforgettable. ”

“ And I do not believe that this movement can be better explained than by supposing that all those of the luminous bodies which are liquid, such as flames, and apparently the sun and the stars, are composed of particles which float in a much more subtle medium which agitates them with great rapidity, and makes them strike against the particles of the ether which surrounds them, and which are much smaller than they. ”

“ The light is sufficient, indeed, to render these earth-born vapours more visible: it is not sufficient to dispel them. A generation of slow and doubtful progress must pass, before the first ray of sunlight can break through the eastern clouds and the full orb of day itself appear. ”

“ The peaceful stars shine like points of flame; the whole air is filled with a blue and tender light, which seems to sleep in the network of vapor wherein it lies. The eye penetrates it without apprehending anything. ”

“ We were not mistaken. (22)
(22 "The fact that gives the phenomenon of the polar aurora its greatest importance is that the earth becomes self-luminous; that, besides the light which as a planet is received from the central body, it shows a capability of sustaining a luminous process proper to itself."—Humboldt.)
There were times when our little craft, driven by wind that was continuous and persistent, shot through the waters like an arrow. Indeed, had we encountered a hidden rock or obstacle, our little vessel would have been crushed into kindling-wood. ”

“ We know our central luminary now as a mass of intensely heated gas, surrounded by a shell of luminous cloud, the photosphere, formed by the cooling of condensable vapors at the surface where exposed to the cold of outer space ”

“ If the communication be through the air without any conductor, a bright light is seen between the bodies, and [378] a sound is heard. In our small experiments, we call this light and sound the electric spark and snap; but in the great operations of nature, the light is what we call lightning, and the sound (produced at the same time, though generally arriving later at our ears than the light does to our eyes) is, with its echoes, called thunder. ”

“ How Heat and Light Travel.—While the little motions or vibrations, of the particles, or atoms, of gas forming the flame of a [Pg 124] candle, the Sun, and other heat and light givers could go on just the same we could not feel their heat or see their light without something or some kind of a substance which would connect them with our bodies and our eyes, like a wire connecting a push button with an electric bell. And there is something which connects us with the most distant stars and that something is called the ether. ”

“ There are wisps and patches of glowing cloud-like material which shine not as our clouds do, by reflecting to us the sunlight. This celestial cloud is no doubt self-luminous; it is, in fact, composed of vapors so intensely heated that they glow with fervor. ”

“ But if we suppose that a flash of lightning, in a particular case, lasts for the thousandth of a second, it would follow, from the above experiments, that the flash is a hundred times as bright, in fact, as it appears to the eye. ”

“ If a large substantial mass, or super-construction, should enter this earth's atmosphere, it is our acceptance that it would sometimes—depending upon velocity—appear luminous or look like a cloud, or like a cloud with a luminous nucleus. Later we shall have an expression upon luminosity—different from the luminosity of incandescence—that comes upon objects falling from the sky, or entering this earth's atmosphere. ”

“ I am speaking of the sun. One small, slender flame of a lamp, which can be extinguished by one breath, spreads its light over all that lies near it: thou seest the light generated by the flame spread out ”

“ In one word, the sphere of darkness in which I floated seemed to be filled with points of light, while the absolute blackness that surrounded them, the absence of the slightest radiation, or illumination of space at large, was strange beyond expression to an eye accustomed to that diffusion of light which is produced by the atmosphere. ”

“ In a previous sermon I have shown you how all the light in the world is derived from the sun, and how all the light in the spiritual world is derived from Jesus Christ. Now, to-day I want to show you that we can extinguish this light. While we cannot prevent the sun from shining, or put out the light there is in the sun, yet we can extinguish, or put out the light of a candle. We can blow out the light, we can turn off the gas, we can cut off the electrical current, and thus prevent the carbon from burning and giving light. ”

“ Let us see if analogy will not help us here. We know that self-luminous bodies send forth vibrations that in turn produce light waves; and these acting upon the organs of sight render visible the objects from which the vibrations proceed. The sun is such a luminous body; and though its material body is some 92,000,000 of miles distant, yet to us men it is a glorious earth-presence, this sun, flooding the earth with light and warmth and life-giving power, without which all life would languish and die. ”

“ What mainly holds the light in our atmosphere after the sun has retired behind the earth is, I imagine, the suspended matter which produces the blue of the sky and the morning and the evening red. Through the reverberation of the rays from particle to particle, there must be at the very noon of night a certain amount of illumination. ”

“ Each globule of moisture floating in the air becomes a reflector of light, and by myriads of reflections and counter reflections the light (which on a clear night is concentrated) is diffused over a large area, producing an illumination which for practical purposes is far superior to that produced on a clear night. When the latter condition prevails the rays of light are so intense on objects immediately surrounding the lamps that one is blinded; so that the places which are in shadow seem darker than they would be if there were no light at all. ”

“ We can give a familiar illustration of gas in a state of extreme tenuity. Look at the beautiful incandescent light with which in these days our buildings are illuminated. How brilliantly those little globes shine! The globe has to be most carefully sealed against the outside air. If there were the smallest opportunity for access, the air from outside would rush in and the lamp would be destroyed. In the preparation of such a lamp elaborate precautions have to be taken to secure that the exhaustion of the air from the little globe shall be as nearly perfect as possible. ”

“ That light is not really and necessarily light—any more than is anything else really and necessarily anything—but an interpretation of a mode of force, as I suppose we have to call it, as light. At sea level, the earth's atmosphere interprets sunlight as red or orange or yellow. High up on mountains the sun is blue. Very high up on mountains the zenith is black. ”

“ A ray of light falls through a chink in a shutter; through the ray, as we watch it, floats an infinite array of tiny motes, and it is through the striking of the light upon them that we are aware of the light ”

“ B. In traversing the atmosphere, the rays, both of the sun, and moon, lose some of their light. For though the pure air, is a transparent medium, which transmits the rays of light freely, we have observed, that near the surface of the earth, it is loaded with vapours and exhalations, by which some portion of them are absorbed. ”

“ Now, as light is supposed to be produced by waves or undulations of an ethereal medium filling all nature, and occupying the pores of the transparent bodies; and as sound is produced by undulations or waves in the air: so the successive production of light and darkness by two bright lights, and the production of sound and silence by two loud sounds, may be explained in the very same manner as we have explained the increase and obliteration of waves formed on the surface of water. ”

“ And late experiments on the sunbeam showed that dark substances imprison the rays,—these absorbing more and delivering less. The more of sun, so much the more of soul; the less of sun, of passion more, and the strange fire. ”

“ We turn night into day with the glow of lamps that burn without flame, and almost without heat, whose mysterious glow is fed from some distant place, that hang in clusters, banners, letters, in city streets, and that glow like new stars along the treeless prairie horizon where thirty years ago even the beginnings of civilization were unknown. ”

“ The vapours mixing with the air in the lower regions near the earth, render it thick, and apt to reflect the sun’s rays on all sides, while the air above remains dark; and because light (that is, white) and darkness (that is, black) , mixed together, compose the azure that becomes the colour of the sky, which is lighter or darker in proportion as the air is more or less mixed with damp vapours.
Chap. CCLVIII.—Why the Shadows of Bodies upon a white Wall are blueish towards Evening.
The shadows of bodies produced by the redness of the setting sun, will always be blueish. ”

“ We see light, the waves of which, or ether vibrations, are transversal; air waves or sound vibrations are longitudinal.
We have spoken of radiant heat. Light acts in the same way through the ether; and when we consider Sound we shall learn that a certain number of vibrations of a string give a certain sound, and the quicker the vibration the shriller the tone. So in light. The more quickly the waves of luminosity travel to our eye, and the faster they strike it, the greater the difference in the colour, or what we call colour. ”