A dipleidoscope is an instrument used to determine true noon. It consists of a small telescope and a prism that creates a double image of the sun. When the two images overlap, it is local true noon. The instrument is capable of determining true noon to within ten seconds. Noon is the time exactly halfway through the day, written 12:00 in the 24-hour clock and 12:00 noon in the 12-hour clock. ... An optical telescope is a telescope which is used to gather, and focus light, for directly viewing a magnified image, making a photograph, etc. ... If a shaft of light entering a prism is sufficiently small such that the coloured edges meet, a spectrum results In optics, a prism is a device used to refract light, reflect it or break it up (to disperse it) into its constituent spectral colours (colours of the rainbow). ...

The dipleidoscope was invented by Giovanni Battista Amici in the first half of the 19th century. Giovanni Battista Amici. ...