Light source

“ As we discover in each party-colored pane the cause of the difference in the color of the ray, we mistake the cause of the difference for the cause of the ray, and assume not only the difference of the ray to depend on the color of the transmitting medium, but deem that medium to be itself the sole source of the light. ”

“ We can study them almost equally well if, instead of dealing with the radiation of light from the particles themselves, we interpose them between us and a light source of more complicated molecular structure, and hotter or more violently excited than the particles themselves. ”

“ They are designed to serve as a curtain to the sun’s body, to prevent a too great intensity of light at his real surface; the higher set of clouds, which are visible to us, being the principal source, or rather agent, of light.
188 It is plain from the foregoing theory, that we never see the real body of the sun, except when we see the spots on his surface: that what we commonly call the sun, are only those bright, luminous phosphorescent clouds, which permanently surround his body, and which give light outwards to the planets, and also inwards to his own inhabitants. ”

“ Light is thrown out on all sides from a luminous body like the spokes of a cart-wheel, and in the absence of any obstruction, the rays are distributed equally on all sides, diverging like the radii drawn from the centre of a circle. As a natural consequence arising from the divergence of each ray from the other, the intensity of light decreases as the distance from the luminous source increases, and vice versâ. ”

“ According to this picture, the energy of a light wave emitted from a point source is not spread continuously over ever larger volumes, but consists of a finite number of energy quanta that are spatially localized at points of space, move without dividing and are absorbed or generated only as a whole. ”

“ The range of brightnesses obtainable by means of light extends from darkness or black throughout the range represented by pigments under equal illumination and beyond these through the enormous range obtainable by unequal illumination of surfaces to the brightnesses of the light-sources themselves. ”

“ It is defined as a substance hot to the feel. [Heat, then, and light are identified as one substance.] [3]
"It has the qualities of earth except smell, taste, and gravity. It is eternal, as atoms; not so, as aggregates.
"Organic luminous bodies are beings abiding in the solar realm. The visual ray, which is the organ of sight, is lucid. Unorganic light is reckoned fourfold: earthy, celestial, alvine and mineral. Another distinction concerns sight and feel; as light or heat may be either latent or manifest, in respect of both sight and feel, or differently in regard to either. ”

“ Light, or the means by which light is propagated, is another of the inorganic elements which forms a portion of the mere material world. The luminiferous ether, if we adopt that theory, or the fluid light of the theory of emission, must indubitably pervade the remotest regions of the universe, and must be supposed to exist, as soon as we suppose the material parts of the universe to be in existence. The origin of light then must be at least as far removed from us as the origin of the solar system. Yet how closely connected are the properties of light with the structure of our own bodies! ”

“ Two bright lights may be made to produce darkness.—If two pencils of light radiate from two spots very close to each other in such a manner that they cross each other at a given point, any object placed at that line of interference will be illuminated with the sum of the two luminous pencils. If we suppose those rays to move in waves, and the elevation of the wave to represent the maximum of luminous effect, then the two waves meeting, when they are both at the height of their undulation, will necessarily produce a spot of greater intensity. ”

“ From these curious discoveries of inductive research we learn some high truths. Associated with light—obeying many of the same laws—moving in a similar manner—we receive a power which is essential to the constitution of our planet. This power is often manifested in such intimate combination with the luminous principle of the solar rays, that it has been suspected to be but another form of the same agency. While, however, we are enabled to show the phenomena of one without producing those which distinguish the other, we are constrained to regard heat as something dis [Pg 88] similar to light. ”

“ For as we dropped swiftly down toward that world we saw at last that the faint light which illuminated it was not artificial light, or reflected light, but light inherent in itself, since all the surface of the mighty sphere glowed with the same phosphorescent light, its plains and hills and valleys alike feebly luminous, with the soft, dim luminosity of radio-active minerals. ”

“ Ordinary light passes through transparent bodies without producing any very striking effects in its passage; but this extraordinary beam of light has the power of insinuating itself between the molecules of bodies, and by illuminating them, and giving them every variety of prismatic hue, of enabling the eye to detect something of the structure of the mass. The chromatic phenomena of polarized light are so striking, that no description can convey an adequate idea of their character. ”

“ We have hitherto considered light chiefly as a simple homogeneous substance, as if all its rays were white, and as if they were all refracted in the same manner by the different lenses on which they fall. Investigations however, into the nature of this wonderful fluid, have demonstrated that this is not the case, and that it is possessed of certain additional properties, of the utmost importance in the system of nature. ”

“ LIGHT AS ACTUALIZATION IS THE BEING OF THE LUMINOUS BODY, AND IS INCORPOREAL.
Thus the light that emanates from bodies is the actualization of the luminous body which is active exteriorly. The light in the bodies whose original nature is such, is the formal being of the originally luminous body. When such a body has been mingled with matter, it produces color. ”

“ 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. ”

“ Where the transverse impulse, which is due to the varying degree of TrÃ1⁄4bung in the light-realm, is directed towards the latter's edge, the intermingling of the Dark-ingredient and the Light-ingredient, contained in that realm, is such that Dark follows Light along its already existing gradient, thereby diminishing steadily. Hence our visual ray, meeting conditions quite similar to those occurring when we look across the light-filled atmosphere into universal space, notifies us of the presence of the blue-violet colour-pole. ”

“ For Light I go directly to the Source of Light, not to any of the reflections. ”

“ Are not the Rays of Light very small Bodies emitted from shining Substances? For such Bodies will pass through uniform Mediums in right Lines without bending into the Shadow, which is the Nature of the Rays of Light. ”

“ What have we here but hope and memory? What see we here but shadows? Shall we then fear to pass pure-handed where Fulfilment is and memory is lost in its own source, and shadows die in the light which cast them? ”

“ And if the ray were completely pure and free from all these atoms and particles, even from the minutest specks of dust, it would appear completely dark and invisible to the eye, since everything that could be seen would be absent from it — namely, the objects of sight. For the eye would find no objects whereon to rest, since light is no proper object of vision, but the means whereby that which is visible is seen ”

“ A substance is said to be coloured when it allows light of one kind to pass through, but absorbs light of a different kind. A block of pitch is opaque to visible light, but transparent to electric radiation; whereas water, which is transparent to light, is opaque to electric radiation. These substances exhibit selective absorption, and are therefore coloured. ”

“ Every substance to be examined must first be made to glow, made luminous; and as nearly everything in the heavens is luminous the instrument has a great range in Astronomy. And when we speak of analysing light, we mean that [Pg 22] the light may be broken up into waves of different lengths. What we call light is a series of minute waves in ether, and these waves are—measuring them from crest to crest, so to say—of various lengths. Each wave-length corresponds to a colour of the rainbow. The shortest waves give us a sensation of violet colour, and the largest waves cause a sensation of red. ”

“ As a matter of fact, we know that all the artificial light stored up for us in combustible materials around us had its origin in that great father of lights, the sun, and that these lesser lights require kindling before they give forth brightness. ”

“ Every ray of light that met our gaze from the broad heavens above us would print an image upon our visual organs of events transpiring in distant worlds, while every electrical flash might convey some idea to our mind never before thought of. Every chemical ray, too, might inform us of scenes far off in the regions of night; and then who can calculate what organic and mental influences might be transmitted to us from beings of all ranks and scattered through all worlds? ”

“ Now let us pass on to the more difficult problem of the nature of the sun itself, and what we know of the changes and commotions going on in that blazing globe of light.
We will try first what we can see for ourselves. If you take a card and make a pin-hole in it, you can look through this hole straight at the sun without injuring your eye, and you will see a round shining disc on which, perhaps, you may detect a few dark spots. ”

“ The phenomena of the interference of beams of light in certain circumstances, to produce darkness or colour, indicate that light is some form of wave motion, and, to carry these waves, a hypothetical luminiferous aether was invented. ”

“ Hence, since the line of sight even across the middle of the space behind the nucleus, passes through a considerable range of luminous matter, while a line within but near the outskirts of that space passes through nearly as great a range of luminous matter as one just outside that space, there should be plenty of light where yet to the eye there seems to be something like absolute darkness. ”

“ What light is, we no more know than the ancients did. According to the modern hypothesis, it is not composed of luminous particles shot out from the sun with immense velocity; but that body only impresses, on the ether which fills all space, a powerful vibratory movement that extends, in the form of luminous waves, beyond the most distant planets, supplying them with light and heat. ”

“ Those who accept the undulatory theory of light are necessitated to believe that all space is pervaded by an exceedingly tenuous fluid which is called ether, and that it is in this medium that the waves of light from self-luminous bodies are produced. ”

“ For, as I have said, the theory professes only to explain the phenomena of radiant visible light. We know very well that light has other bearings and properties. It produces chemical effects. The optical polarity of crystals is connected with the chemical polarity of their constitution. The natural colors of bodies, too, are connected with their chemical constitution. Light is also connected with heat. The undulatory theory does not undertake to explain these properties and their connexion. If it did, it would be a Theory of Heat and of Chemical Composition, as well as a Theory of Light. ”

“ Take a small globe, and stick a piece of black plaster over England, then let a lighted lamp represent the sun, and turn the globe slowly, so that the spot creeps round from the dark side away from the lamp, until it catches, first the rays which pass along the side of the globe, then the more direct rays, and at last stands fully in the blaze of the light. ”

“ Hence, if two lights of unequal illuminating powers shine upon the same surface at equal obliquities, and an opake body be interposed between them and the illuminated surface, the two shadows produced, must differ in blackness or intensity in the same degree. ”

“ All this light and heat comes through space that is 200° below zero, through utter darkness, and appears only on the earth. So the gas is darkness in the underground pipes, but light at the burner. So the electric power is unfelt by the cable in the bosom of the deep, but is expressive of thought and feeling at the end. Having found the cause of light, we will commence a study of its qualities and powers.
Light is the astronomer's necessity. When the sublime word was uttered, "Let there be light!" the study of astronomy was made possible. ”

“ From the nature of reflecting curves, it follows that the smaller a luminous point is, the more perfectly will its emanations be reflected; for a focus is a point of the smallest magnitude, if, indeed, it has any dimensions. My idea, then, is to make a focus of a line of light very minute in it’s section, but as large, in it’s contents, as may be desired: thus securing a considerable fasces of luminous particles while using them in an economical manner. ”