CONTENTS. 



PAGB 



Irregular movements of Uranus; Adams and Leverrier calculate 

 the position of an Unknown Planet Neptune found by these 

 calculations in 1846 A Survey of the whole Heavens made by 

 Sir John Herschel His work in Astronomy Comets and 

 Meteor-systems 287 



CHAPTER XXXII. 



SCIENCE OF THE NINETEENTH CENTURY (CONTINUED). 



Discoveries concerning Light made in the Nineteenth Century 

 Birth and History of Dr. Young He explains the Interference 

 of Light Cause of Prismatic Colours in a Shadow And in a 

 Soap-bubble Malus discovers the Polarisation of Light caused 

 by Reflection Birth and History of Fresnel Polarisation of 

 Light explained by Young and Fresnel Complex Vibrations of 

 a Ray of Light How these Waves are reduced to two separate 

 Planes in passing through Iceland -spar Sir David Brewster 

 and M. Biot explain the colours produced by Polarisation . . 302 



CHAPTER XXXIII. 



SCIENCE OF THE NINETEENTH CENTURY (CONTINUED). 



History of Spectrum Analysis Discovery of Heat-rays by Sir W. 

 Herschel And of Chemical Rays by Ritter of Jena Photo- 

 graphy first suggested by Davy and Wedgwood Carried out by 

 Daguerre and Talbot Dark Lines in the Spectrum first ob- 

 served by Wollaston Mapped by Fraunhofer Life of Fraun- 

 hofer He discovers that the Dark Lines are different in Sun- 

 light and Star-light Experiments on the Spectra of different 

 Flames Four new Metals discovered by Spectrum Analysis 

 Artificial Dark Lines produced in the Spectrum by Sir David 

 Brewster Bunsen and Kirchhoff explain the Dark Lines in the 

 Solar Spectrum Metals in the Atmosphere of the Sun Huggins 

 and Miller examine the Stars and Nebuloe by Spectrum Analysis . 315 



