48 A CENTURY'S PROGRESS IN ASTRONOMY. 



scientists at Munich, who provided him with 

 books on optics and mathematics. Meanwhile the 

 young optician occupied his time in shaping 

 and finishing lenses. In 1806 he entered the 

 optical department of the Optical and Physical 

 Institute of Munich, and the following year, 

 when only twenty years of age, was appointed 

 to the chief post in that department. In 1814 

 he commenced his investigations with the prism, 

 which have made his name famous. 



Newton had found that, in passing through a 

 prism, white light is dispersed into its primary 

 colours, making up the band of coloured light 

 known as the solar spectrum. But he failed 

 to recognise the existence of dark lines in the 

 spectrum. Casually seen in 1802 by William 

 Hyde Wollaston (1786-1828), an English physicist, 

 these lines were first thoroughly examined by 

 Fraunhofer. Allowing light from the Sun to 

 pass through a prism attached to the telescope, 

 he was amazed to find several dark lines in 

 the spectrum. By the year 1814 he had de- 

 tected no less than 300 or 400 of these lines. 

 Fraunhofer named the more prominent lines by 

 the letters of the alphabet, from A in the red 

 to H in the violet. They are now known as 

 the Fraunhofer lines. At first he was much 

 perplexed regarding the nature of the dark lines. 



