A spectroscope is a device which measures the spectrum of light. Early spectroscopes were simply a prism with graduations marking wavelengths. Modern spectroscopes generally use a diffraction grating, a movable slit and some kind of photodetector[?], all automated and controlled by a computer.
... Herjulfsson[?] - Viking discoverer of North America
Thor Heyerdahl, (1914-2002), Norwegian explorer
Henry Hudson, (died 1570), discovered the Hudson River and sailed up ...