the world > matter > physics > electromagnetic radiation > light > chromatism > [noun] > spectrum > light or rays beyond (3)
Photography. lavender rays, ultraviolet radiation. Obsolete.
dark or invisible rays; spec. heat-rays of the solar spectrum. Now rare.
(a) light supposed to be able to pass through objects that are opaque to the eye (now historical); (b) light (electromagnetic radiation) with a…