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accidental color achromatic angle of incidence aperture axes axis of double beam blue bodies bright centre CHAP common light concave lens convex lens crown glass crystals curve diameter direction dispersive power diverging rays double refraction equal equation extreme ray flint glass focal distance focal length formula fringes green heat Iceland spar inches incident rays inclination index of refraction inverted lenses luminous negative object glass observed optical orange parallel rays particles pencil of rays perpendicular phenomena placed plane of polarization plano-convex lens plate polarized light positive principal focus prism prismatic produced radiant point radius reflected rays refractive power retina rhomb second surface seen shown in fig side small pencil spectrum speculum sphere spherical aberration suppose system of rings telescope thickness tint tion transmitted vergency vertex vision vitreous humor whence white light yellow
Page 34 - 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 219 - When the rising sun shines from that point whence its incident ray forms an angle of about 45° on the sea of Reggio, and the bright surface of the water in the bay is not disturbed either by the wind or the current, the spectator being placed on an eminence of the city, with his back to the sun and his face to the sea, on a sudden...
Page 143 - Massinger is one of the most interesting as well as one of the most...
Page 95 - ... parts, the orange 27, the yellow 48, the green 60, the blue 60, the indigo 40, and the violet 80...
Page 68 - ... very little of the violet. The yellow space, which has not been much absorbed, has increased in breadth. It occupies part of the space formerly covered by the orange on one side, and part of the space formerly covered by the green on the other. Hence it follows, that the blue glass has absorbed...
Page 218 - A bark about 4000 toises distant was seen approaching Geneva by the left bank of the lake, and at the same moment there was seen above the water an image of the sails, which, in place of following the direction of the bark, receded from it, and seemed to approach Geneva by the right bank of the lake ; the image sailing from east to west, while the bark was sailing from north to south.
Page 104 - ... 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 221 - 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 which they had been accustomed to visit : such as the bay, the windmill at Boulogne, St.
Page 137 - ... left, or on any other side of it, provided that in all these cases it falls upon the surface in the same manner, or, what amounts to the same thing, the beam of solar light has the same properties on all its sides; and this is true, whether it is white light as directly emitted from the sun, or whether it is red light, or light of any other colour.
Page 255 - With the aid of these facts, the theory of accidental colors will be readily understood. When the eye has been for some time fixed on the red wafer, the part of the retina occupied by the red image is strongly excited, or, as it were, deadened by its continued action.