The light which we see is the visible part of what is called the electromagnetic spectrum, which extends from gamma rays, through X-rays, ultraviolet, visible, infra-red, microwave, to short medium and long radio waves. Such electromagnetic waves are characterised by their ability to undergo reflection and refraction, to exhibit interference and diffraction effects, and to be polarised (Chambers 1988,293). Visible light can be further subdivided, since "white light" from the sun can be broken down into its spectral colours. Instruments related to spectroscopy, which make use of this property, have been detailed in an earlier section of this Catalogue (see pages 25-29 in the Section on Chemistry and Analysis), since they are commonly used to give information about the chemical nature of the substances under study. In this section, we list sources of visible light and instruments which illustrate various properties of white light. Included also are lanterns, together with such fundamental instruments as microscopes and telescopes, which use the refraction of light through lenses for the study of the microscopic to the astronomical. Maynooth has a good selection of instruments under this heading, some of the best being of French origin, but also including two particularly fine instruments (the polarising microscope 244 and the Norremberg polariscope 272) by the Dublin firm of John Spencer and Son.

Topics covered include the following:

	Camera Lucida
	Heliostats
	Kaleidoscopes
	Lamps
	Lanterns
	Microscopes and Telescopes
	Optical Models and Elements
	Phosphoroscopes
	Photometers
	Polarimeters
	Polariscopes
	Other Optical Instruments

Camera Lucida