The Optical Indicatrix and the Transmission of Light in Crystals

a²x² biaxal crystals calcite coincides cone conjugate plane corresponding ray corresponding ray-front curve cylinder direction of transmission direction of vibration direction-cosines disturbance double refraction elastic ether elastic force elastic theory ellipse ellipsoid equal equation expression Fresnel front-normal ƒ₁² ƒ² generalisation geometrical given direction Hence identical inclined indicatrix initiatory force intersects line of transmission luminiferous ether lying magnitude medium morphological axis normal RN Op₁ optic axes OPTIC BI-RADIALS optical characters Or₁ ortho-rhombic crystal Os₁ parallel periodic change perpendicular plane AOC plane of polarisation plane of symmetry plane RNOr plane-polarised ray points R1 polarised ray R₁ radius vector ray of light ray-front corresponding ray-surface rays transmissible relation represented respectively resultant effect right angles simple colour spheroid surface symmetral plane tangent plane termed tion transmitted transverse plane uniaxal crystal velocity of transmission velocity-factor wave-surface zero