Light reflection

“ Another principle is Reflection, by which heat radiated to a surface is turned back from it when not absorbed or allowed to pass through; just as a ball rebounds from a wall; just as sound is thrown back from a hill, making echo; just as rays of light are reflected from a mirror. ”

“ The facts we have stated above, and the variety of modes by which light may be refracted and reflected by different substances in nature, lead us to form some conceptions of the magnificent and diversified scenes which light may produce in other systems and worlds, under the arrangements of the all-wise and Beneficent Creator. Light, in all its modifications and varieties of colour and reflection, may be considered as the beauty and glory of the universe, and the source of unnumbered enjoyments to all its inhabitants. ”

“ The brighter the objects reflected, the larger the angle at which reflection is visible; it is always to be remembered that, strictly speaking, only light objects are reflected, and § 7. The inherent hue of water modifies dark reflections, and does not affect bright ones.that the darker ones are seen only in proportion to the number of rays of light that they can send; so that a dark object comparatively loses its power to affect the surface of water, and the water in the space of a dark reflection is seen partially with the image of the object, and partially transparent. ”

“ In the original picture these contrasts would depend partly on the color of the various objects; but here, in the black and white reproduction, we may think of the pattern simply as one of very dark spots and very light ones, threaded together by others of varying depths of greyness. Again, what an important part the sky plays! It is a flood of light, against which everything forms a silhouette, [4] more or less dark, relieved by spots and streaks of light. The water, but for the pathway of reflection, is shrouded in shadow. ”

“ 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. ”

“ At the outset we have such purely physical questions as the nature of light, the cause of its emission, the mode of its propagation, the difference in the waves which give rise to the various color sensations, the principles of absorption, of reflection and of refraction, and the nature of material surfaces whereby they acquire their characteristic colors. ”

“ Since the brightness of a reflected image depends upon the quantity of light, it is quite evident that those images which arise from total reflection are by far the most vivid, as in ordinary cases of reflection a portion of light is absorbed. ”

“ In short, the effects produced by the refraction and reflection of light on the scenery connected with our globe, teach us that these principles, in the hand of the Almighty, might be so modified and directed, as to produce the most picturesque, the most glorious and wonderful phenomena, such as mortal eyes have never yet seen, and of which human imagination can form no conception ”

“ When the light falls on a diaphanous body which is full of an infinity of little pores, as the air, it passes through without causing any reflection. When the light falls on a body entirely opake, as a flower, for instance, not being able to penetrate it, its ray is reflected from it, and returns from the flower to the eye, to which it carries the species, and renders the colors distinguishable, according to the angles formed by reflection. ”

“ That colours, as visible to the eye, are all formed in the solar light, and their appearance depends upon the absorption of some of the rays of light, and the reflection of others, is a doctrine which followed the discoveries of Sir Isaac Newton. ”

“ OF SHADOWS ON BODIES. When you represent the dark shadows in bodies in light and shade, always show the cause of the shadow, and the same with reflections; because the dark shadows are produced by dark objects and the reflections by objects only moderately lighted, that is with diminished light. And there is the same proportion between the highly lighted part of a body and the part lighted by a reflection as between the origin of the lights on the body and the origin of the reflections. ”

“ We observe, for instance, in his chapter on Sensation (p. 236 seq.) that all light-waves are the same in kind of movement, but differ in size as widely as the ripples on a sea-beach (round which happy children play) differ from the vast Atlantic ship-engulfing billows sixty or a hundred feet apart. All these undulations are similar in respect of reflection, refraction, interference, diffraction, and polarisation, as well as in their production of heat. [124] Now, it is the interpretation of such movements into its own language by which our eye gives us the sensation of colour. ”

“ Self-illuminating and dark bodies, transparent and opaque, straight path of light, shade, rate of transmission, reflection, refraction, diffusion of color, convex and concave lenses, microscope, telescope, camera, the eye, spectacles. ”

“ The property of reflection is also illustrated on a grand scale in the illumination of our satellite, the moon, and the various planetary bodies which shine by light reflected from the sun, and have no inherent self-luminosity. Aristotle was well aware that it is the reflection of light from the atmosphere which prevents total darkness after the sun sets, and in places where the sun's rays do not actually fall during the daytime. ”

“ Higher settings have been devised which permit the light to radiate more fully from all angles of the facet surfaces. The powers of reflection of which we know more now than in former years are thus used in additional interplays of light. ”

“ I admit that strong lights frequently continue for some time thus visible in the ‘mind’s eye;’ and it is well known that such impressions are often followed by images of similar shape, but of various colours. In passing from sunshine to a dark room, we frequently witness the appearance of stars and circles of vari-coloured light ”

“ A corresponding effect occurs when one suddenly exposes to darkness the eye adapted to light. One can easily observe what goes on then, if, after looking for a time at an undifferentiated light surface such as the evenly luminous sky, one covers the opened eyes with the hollowed hands. ”

“ The same effect may be observed when looking at the setting sun, or a flaring gas light. If the light at which we look is coloured, we shall see the complementary colour in the impression left on the retina. ”

“ I wish thee to believe that light in the bodies that we call luminous is nothing more than a very brisk and violent motion, which, by means of the air and other transparent media, is conveyed to the eye, exactly as the shock through the walking-stick reaches the hand of a blind man. ”

“ To a short-sighted person, colours run together and intermix, outlines disappear, blues and reds and yellows become russets or browns, the lamps or candles of an illumination spread into an unmeaning glare, or dissolve into a milky way. He takes up an eye-glass, and the mist clears up; every image stands out distinct, and the rays of light fall back upon their centres. ”

“ He may very easily perceive, that it proceeds onely from the variety of the Reflections of light, which is caus'd by the various shape of the Particles, or little protuberant parts of the thread that compose the surface; and that those parts of the waves that waves that appear the brighter, throw towards the eye a multitude of small reflections of light, whereas the darker scarce afford any. ”

“ 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. ”

“ Modification of dark reflections by shadow.across a space of water of strong local color, receiving, alternately, light and dark reflections, it has no power of increasing the reflectiveness of the water in the bright spaces, still less of diminishing it ”

“ If, for example, we look steadfastly at the sun for a second or two, and then immediately close our eyes, the image, or spectrum, of the sun remains for a long time present to the mind, as if the light were still acting on the retina. ”

“ A transparent Body which looks of any Colour by transmitted Light, may also look of the same Colour by reflected Light, the Light of that Colour being reflected by the farther Surface of the Body, or by the Air beyond it. And then the reflected Colour will be diminished, and perhaps cease, by making the Body very thick, and pitching it on the backside to diminish the Reflexion of its farther Surface, so that the Light reflected from the tinging Particles may predominate. ”

“ 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. ”

“ Probably the small amount of light reflected by transparent glass, which gives a passage to the greater part of the rays, may serve to illustrate the small amount of light reflected from black surfaces, which absorbs the greater portion of light. ”

“ The light of the sun always reflects a shadow equal to the object which it projects on a parallel plane. The sun being larger than the body illumined, throws a shadow less than that body. On the contrary, the light of a candle, being less than the object reflected, produces the contrary effect, the shadow increasing as it retires, not in parallels, but in rays, thrown by the light. ”

“ Light is called polarized, which, having been once reflected or refracted, is incapable of being again reflected or refracted in certain positions of the second medium. Ordinarily, light which has been reflected from a pane of glass or any other substance, may be a second time reflected from another surface, and will also freely pass through transparent bodies. ”

“ Uses of Refraction. If it were not for refraction, or the deviation of light in its passage from medium to medium, the wonders and beauties of the magic lantern and the camera would be unknown to us; sun, moon, and stars could not be made to yield up their distant secrets to us in photographs; the comfort and help of spectacles would be lacking, spectacles which have helped unfold to many the rare beauties of nature, such as a clear view of clouds and sunset, of humming bee and flying bird. ”

“ Thirdly, in the Night-time the Eye being placed in the shadow of the Earth, those reflexions of a Star will be yet more easily visible; whenas the great light of the Sun by Day must needs much debilitate these reflected Images of the Objects upon the Earth, his beams striking our Eyes with so strong vibrations. ”

“ Of course the effect of such abrupt transitions from perfect illumination to total darkness, if it were the plan of Nature, would be most inconvenient and painful, if not destructive to the eyes. We are protected from this by the phenomena of double shadows, and the gradual passage from darkness to light, although each luminous ray moves undeviatingly in its straight line. ”

“ Fading Illumination. The farther we move from a light, the less strong, or intense, is the illumination which reaches us; the light of the street lamp on the corner fades and becomes dim before the middle of the block is reached, so that we look eagerly for the next lamp. The light diminishes in brightness much more rapidly than we realize, as the following simple experiment will show. Let a single candle [106] (Fig. 57) serve as our light, and at a distance of one foot from the candle place a photograph. ”

“ The reflected light waves not only make us see things, but they make us see them in different colors. Imagine a sunbeam playing on a leaf: part of its waves bound straight back from it to our eye, and make us see the surface of the leaf ”

“ Light, through the medium of the eye, not only unfolds to us the persons of others, in all their minute modifications and peculiarities, but exhibits us to ourselves. It presents to our own vision a faithful portrait of our peculiar features behind reflecting substances, without which property we should remain entirely ignorant of those traits of countenance which characterize us in the eyes of others.
But, what is the nature of this substance we call light, which thus unfolds to us the scenes of creation? ”

“ And indeed it is the light itself, which after a certain manner, either mixed with shades or other-wise, strikes our eyes and immediately produces that motion in the organ which gives us the color of an object. ”

“ 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. ”

“ In order to produce a mental impression of the facts, two distinct methods may be followed:--the first, to shade downwards from the lights, making everything darker in due proportion, until the scale of our power being ended, the mass of the picture is lost in shade. The second, to assume the points of extreme darkness for a basis, and to light everything above these in due proportion, till the mass of the picture is lost in light. ”