Noah Webster
Spectrum
SPEC'TRUM, noun [Latin] A visible form; an image of something seen, continuing after image of something seen, continuing after the eyes are closed, covered or turned away. This is called an ocular spectrum
SPEC'TRUM, noun [Latin] A visible form; an image of something seen, continuing after image of something seen, continuing after the eyes are closed, covered or turned away. This is called an ocular spectrum