of the action of pigments upon, 33 ——­absorption, 34 ——­mixture of pigments contrasted with mixture of lights, 37 ——­Wuensch on three simple colours in white light, 39 note ——­Newton arrives at the emission theory, 45 ——­Young’s discovery of the undulatory theory, 49 ——­illustrations of wave-motion, 58 ——­interference of sound-waves, 58 ——­velocity of, 60 ——­principle of interference of waves of, 61 ——­phenomena which first suggested the undulatory theory 62-69 ——­soap-bubbles and their colours, 62-65 ——­Newton’s rings, 69-77 ——­his espousal of the emission theory, and the results of this
    espousal, 77
——­transmitted light, 77 ——­diffraction, 77, 89 ——­origin of the notion of the attraction of gravitation, 92 ——­polarity, how generated, 93 ——­action of crystals upon, 98 ——­refraction of, 106 ——­elasticity and density, 108 ——­double refraction, 109 ——­chromatic phenomena produced by crystals in polarized, 121 ——­the Nicol prism, 122 ——­mechanism of, 125 ——­vibrations, 125 ——­composition and resolution of vibrations, 128 ——­polarizer and analyzer, 127 ——­recompounding the two systems of waves by the analyzer, 129 ——­interference thus rendered possible, 131 ——­chromatic phenomena produced by quartz, 139 ——­magnetization, of, 141 ——­rings surrounding the axes of crystals, 143 ——­colour and polarization of sky, 149, 154 ——­range of vision incommensurate with range of radiation, 159 ——­effect of thallene on the spectrum, 162 ——­fluorescence, 162 ——­transparency, 167 ——­the ultra-red rays, 170 ——­part played in Nature by these rays, 175 ——­conversion of heat-rays into light-rays, 176 ——­identity of radiant heat and, 177 ——­polarization of heat, 180 ——­principles of spectrum analysis, 189 ——­spectra of incandescent vapours, 190 ——­Fraunhofer’s lines, and Kirchhoff’s explanation of them, 193 ——­solar chemistry, 195-197 ——­demonstration of analogy between sound and, 198, 199 ——­Kirchhoff and his precursors, 201 ——­rose-coloured solar prominences, 204 ——­results obtained by various workers, 205 ——­summary and conclusion, 206 ——­polarized, the spectra of, 227 ——­measurement of the waves of, 234

Lignum Nephriticum, fluorescence of, 164

Lloyd, Dr., on polarization of heat, 180, 209

Lockyer, Mr., on the rose-coloured solar prominences, 205

Lycopodium, diffraction effects caused by the spores of, 88

Magnetization of light, 141

Malus, his discovery respecting reflected light through Iceland spar, 115 ——­discovers the polarization of light by reflection, 208

Masson, his essay on the bands of the induction spark, 202

Melloni, on the polarization of heat, 180

Metals, combustion of, 5, 6 ——­spectrum analysis of, 190 ——­spectrum bands proved by Bunsen and Kirchhoff to be characteristic of the vapour of, 192

Mill, John Stuart, his scepticism regarding the undulatory theory, 149

Miller, Dr., his drawings and descriptions of the spectra of various coloured flames, 201