The History of Infrared Photography (contd.)
		• Using a glass prism to refract light from the sun into its component colors, he moved thermometers through the spectrum. The temperatures increased as the thermometers were moved from violet to red and reached a maximum in the dark region beyond the red end of the visible spectrum. • The Royal Society of London was notified of this discovery in 1800. In his writings, Herschel referred to this phenomenon as “invisible light”.
				Herschel's Prism and Mirror c1800