Curiosities of Light and Sight

achromatic after­image allthe andthe aperture apparatus appear asthe astigmatism atthe blue and yellow blueand border bright byan bythe centre chromatic aberration ciliary muscle circular coloured glasses coloured light complementary colours crystalline lens dark reaction diffusion circles disk distance effect electric lamp ether ether wave excitation experiments filament focussed green greenish­ greenish­blue grey horizontal illusion inches inthe isan isin isnot itis lantern layer length lens lenses lines little spectrum luminosity luminous point mental plane mental standard millimetre nerve­fibres observed ofthe optical orange paper patch phenomena phenomenon physical portion produced purple recurrent image red rays refracted refrangibility retina rotate sector seen sensation shown in Fig slit spot standardof stencil suchas suitable thatthe theeye thelight themiddle themost theory of colour Thepatch thespectrum tint tobe transmitted uponthe vertical violet vision vitreous body wave­ wave­length whenthe wherethe whichis whichthe white light white screen willbe withthe wouldbe