An Elementary Treatise on Geometrical Optics

achromatic angle of incidence angle of refraction astronomical telescope called Cambridge centre coincide cone consider converge convex lens cos² diameter direction dispersive power diverge edge emergence equal excentrical eye-glass eye-lens eye-piece F₁ Find the position focal length foci formula geometrical focus glass Hence illumination image formed inches incident pencil incident ray index of refraction internal reflection J. W. DONALDSON last Article late Fellow lenses luminous point magnifying power minimum deviation object-glass parallel rays pass pencil of light pencil of parallel perpendicular plane mirror portion primary plane prism produced prove radius ratio ray of light real image reflecting surface refracted pencil refracted ray refraction or reflection refractive index respectively right angles screen second medium secondary focus Shew small pencil spectrum sphere spherical surface St John's College tion Treatise triangle Trinity College velocity vertex virtual image