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aberration achromatic angle of incidence aperture axes axis of double beam blue bodies bright centre common light concave lens converging convex lens crown glass crystals diameter different colours direction dispersive power diverging double refraction equal film flint glass focal distance focal length focus F formed fringes green heat Hence Herschel Iceland spar inch incident ray inclination index of refraction lenses luminous mirror Newton object glass observed optical orange parallel rays particles pencils perpendicular phenomena placed plane of polarisation plane of reflexion plane passing plano-convex lens plate of glass polarised light polarising angle position prism produced radiant point radius ray of light reflected refracted ray refractive power retina rhomb round second surface seen shown in fig spectra spectrum speculum sphere spherical spherical aberration system of rings telescope thickness tints transmitted transparent tube violet rays vitreous humour white light yellow
Page 30 - It may also be defined as the sine of the angle of incidence divided by the sine of the angle of refraction, as light passes from air into the substance.
Page 157 - IF we transmit," says Dr. Brewster, " a beam of the sun's light through a circular aperture into a dark room, and if we reflect it from any crystallized or uncrystallized body, or transmit it through a thin plate of either of them, it will be reflected and transmitted in the very same manner and with the same intensity, whether the surface of the body is held above or below the beam, or on the right side or left, or on any other side of it, provided that in all these cases it falls upon the surface...
Page 72 - To the same degree of Refrangibility ever belongs the same colour, and to the same colour ever belongs the same degree of Refrangibility.
Page 312 - ... a defect in the sensorium, by which it is rendered incapable of appreciating exactly those differences between rays on which their colour depends.
Page 118 - ... a grooved structure, like the delicate texture of the skin at the top of an infant's finger, or like the section of the annual growths of wood as seen upon a dressed plank of fir. These may sometimes be seen by the naked eye ; but they are often so minute that 3,000 of them are contained in an inch.
Page 263 - French coast, which is about 40 or 50 miles distant, as distinctly as through the best glasses. The sailors and fishermen could not at first be persuaded of the reality of the appearance ; but as the cliffs gradually appeared more elevated, they were so convinced that they pointed out and named to Mr. Latham the different places they had been accustomed to visit : such as the bay, the windmill at Boulogne, St Vallery, and other places on the coast of Picardy.
Page 71 - For they also receive their colour from their power of stopping or absorbing some of the colours of white light, and transmitting others. As for example, black and red inks, though equally homogeneous, absorb different kinds of rays ; and, when exposed to the sun, they become heated in different degrees ; while pure water seems to transmit all rays equally, and is not sensibly heated by the passing light of the sun. The rich dark light transmitted by a smalt-blue finger-glass is not a homogeneous...
Page 268 - ... the primary bow. On the outside of the outer or secondary bow, I saw distinctly a red arch, and beyond it a very faint green one, constituting a supernumerary bow, analogous to those within the primary rainbow.
Page 74 - Fig. 51. yellow spectrum has its maximum intensity at Y, the intensity declining to zero at M and N; and the blue has its maximum intensity at B, declining to nothing at M and N. The general curve which represents the total illumination at any point will be outside these three curves, and its ordinate at any point will be equal to the sum of the three ordinates at the same point. Thus the ordinate of the general curve at the point Y will be equal to the ordinate of the yellow...