SPECTRUM

tho namo given to a banc of light which has entered through ¢ narrow alit, and been projected on a screer in a darkened chamber, after undergoing dispersion in pa ing on & prism o prisms placed in ite path. the case o! white light, such as sunlight, the electric light, or lime-light, the spectrum is composed of a series of coloured bands arranged in the following order—red. orange, — green, blue, indigo, and violet. Red light gives a red spectrum, green light a grecn spectrum, and sc on. [s. 285]