118 LIGHT. 



CHAPTER VII. 



LIGHT. 



Theories of the Nature of Light Hyjiotheses of Newton and 

 Huygens Sources of Light The- Sun -Velocity of Light 

 Transparency Dark Lines of the Spectrum Absorption of 

 Light Colour Prismatic Analysis Kays of the Spectrum 

 Rainbow Diffraction Interference Goethe's Theory- 

 Polarisation Magnetisation of Light Vision The Eye 

 Analogy Sound and Light Influence of Light on 

 Animals and Vegetables Phosphorescence arising from 

 several Causes Artificial Light Its Colour dependent 011 

 Matter. 



LIGHT, the first creation, presents to the enquiring 

 mind a series of phenomena of the most exalted cha- 

 racter. The glowing sunshine, painting the earth with 

 all the brilliancy of colour, and giving to the landscape 

 the inimitable charm of every degree of illumination, 

 from the grey shadow to the golden glow; the calm of 

 evening, when, weary of the " excess of splendour," the 

 eye can repose in tranquillity upon the "cloud-land" 

 of the west, and watch the golden and the ruddy hues 

 fade slowly into the blue tincture of night ; and the 

 pale refulgence of the moon, with the quiet sparkle of 

 the sun-lit stars, all tend to impress upon the soul, the 

 great truth that, where there is light, organisation and 

 fife are found, and beyond its influence death and silence 

 hold supreme dominion.* Through all time we have 



* " These oxygen, hydrogen, nitrogen, and carbon are the 

 four bodies, in fact, which, becoming animated at the fire of the 

 sun, the true torch of Prometheus, approve themselves upon the 

 earth the eternal agents of organisation, of sensation, of motion, 

 and of thought." Dumas, Lecons de Philosophic Chimique, p. 100. 

 Paris, 1837. 



