A Treatise on Optics

angle of incidence aperture Apophyllite axes axis of double beam Biot blue bodies calcareous spar centre circle circular common light concave convex convex lens crown glass crystallised crystals diameter different colours direction distance double refraction edge equal exhibited experiments film flint glass fluid focal length focus formed fringes green halo heat Iceland spar inch inclination index of refraction lens lenses lines luminous maximum polarising mirror object glass observed optical orange parallel particles pencils perpendicular phenomena plane of polarisation plane of reflexion plate of glass polarised light polarised ray polarising angle position prism prismatic produced quartz reflected refracted ray refractive power retina rhomb right angles round second surface seen shown in fig spectrum spherical aberration sulphate of lime system of rings telescope thickness tints tion transmitted transparent violet vitreous humour white light yellow