CHAPTER V 



THE PHYSICS OF THE NINETEENTH CENTURY 



The Mechanical View of Nature The Popularization of Science 

 Astronomy The Nebular Hypothesis " Phlogiston" Lavoisier and 

 the Conservation of Matter Imponderable Fluids The Atomic 

 Theory The Wave Theory of Light Spectrum Analysis Heat and 

 the Theory of Energy The Rise of Electrical Science Electric 

 Waves The Theory of Ions Summary. 



IF, in the story of knowledge, the French Revolution 



marked the end of the period which began with the 



The Renaissance, yet many of the ideas which 



M Vkw n of al influenced the thought of the succeeding 

 Nature. years were moving within its turmoil. 

 Indeed the lines of advance which were to be charac- 

 teristic of the new age had begun to appear here and 

 there before that political cataclysm closed the 

 eighteenth century. Thus, in the various branches 

 of knowledge whose fortunes we pursue, our division 

 cannot be made at a definite point of time. In 

 every case we must turn back a few years to trace 

 the origins of the threads we shall follow. 



The broad tendency of the period now under review 

 is to be sought in the gradual extension of the mechani- 

 cal view of nature, which took its rise in the triumphs 

 of the Newtonian astronomy as interpreted chiefly 

 by French mathematicians, to other branches of know- 



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