236 



INDEX. 



Page. 



Nicol's prisra 12I 



Nodal points in undulation curves j^gg 



Normals to circular sections of surface of elasticity ooo 



Notions, early, prevalent respecting light 108 



Numbers of undulations of light per second 171 



compared with those of sound I7I 



Oblique incidences of light.eflfects on Newton's rings 120 184 



on colors of crystaUine lamina; 1:j3 



Opaque bodies, narrow, in divergent light have fringed shadows I75 



Opposite molecular gyrations, resultant of 093 



produce no interference -jO;} 



Optic axes of crystal II5 13;) oig 007 



of two-axed crystals, how situated '....' 227 



Optical treatise of Euclid IQg 



of Ptolemy 1 og 



Ordinary and extraordinary rays, in double refraction 11 5 



terms not applicable in case of crystals of two axes 213 



Origin of interfering waves must be common 1C8 



Partial reflection of common light, elliptic polarization produced by 138 



Pasteur, his researches on rotatory polarization j 42 



Pendulum, vibrations of l.jg 



Phase of vibration or undulation deiined 150 



changed by reflection lyS 



Phenomena of ordinary refraction 110 



of double refraction 115-17 



Piles of glass plates used as polarizers 130 



transparency of i:!l 



Plane of incidence lOii 



of refraction lOg 



of polai'ization 12y 



of ditto for refracted raya in double refraction 218-20 



changed by reflection iy5 



rotated by magnetism 204 



as related to direction of molecular movement 216-17 



Plates, thin, colors produced by 118-20 



thick, colors produced by . 120 



crystalline, in polarized light 132-34, 204-15 



of glass, piles of used as polarizers 130 



Points of inosculation of wave surface 225-30 



neutral, iu atmosphere 143 



nodal, in undulation curves 1<I8 



Polar clock, Wheatstone's 143 



Polariscopes, Nicol s 131 



Delezcnne's 132 



tourmaline 132 



Polarization of light, discovery of 118, 127 



physical theory of 188-95 



chromatics of 204-15 



amount of, at any incidence 195 



plane of, defined 129 



atmospheric 14'{ 



plane 188-95 



circular 137, 192 



elliptic 138, 198 



rotatory, theory of 200 



of quartz 135 



of liquids 141 



of salts 142 



produced by heat, cold, torsion, tension, or pressure 140 



plane of, changed by reflection 195 



rotated by magnetism 204 



Polarized light, properties of 118-27 



colors of crystalline plates in 132-34, 204-13 



interferences of . 204-15 



general phenomena of 118-27 



Polarizing piles of glass 130 



eye-pieces 131-32 



mirrors 133 



angle 127-8 



Brewster's law of 128 



Positive and negative crystals in double refraction 116, 222, 2: iO 



Pressure imparts polarizing properties to solids 140 



Primitive forms of crystals possessing polarizing power 141 



Principle of Huyghens concerning elementary wave composition 157 



Principal sections of crystals 116 



of wave surface 226 



Prismatic spectrum Ill 



fixed lines in 125-27 



Prism, Arago's 170 



Presuel's 136 



Nicol's 131 



Progressive motion of light 121-25 



Progress of wave and ray in double refraction distinguished 224 



Ptolemy, his experiments on refraction 108 



"Quarter-wave lamina," Airj''s 139, 206 



Quartz, crystallogrnphic peculiarities of 1.35 



rings of, discovered by Brewster 135 



