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.
... but the Presbyterian Church (USA), in order to embrace the historical expressions of the whole Reformed tradition as found in the United States, has adopted a Book of ...