General Introduction 



he accompanies a master spirit, the benefit will 

 not be wholly on the learner's part. Men of 

 science work all the more happily, with all the 

 better effect, when the public has an intelligent 

 sympathy with their aims and achievements. 

 To further and deepen that sympathy is the 

 purpose of these MASTERPIECES OF SCIENCE. 



In some cases the pages here reproduced have 

 been abridged and a few slight changes effected 

 in the text. Here and there a technical term 

 of an unusual kind is followed by a definition in 

 brackets, or a translation is affixed to a foreign 

 word. The notes which preface each successive 

 chapter may serve the reader as windows of out- 

 look upon literature which may gainfully supple- 

 ment the books which here fill his hand. 



GEORGE ILES. 



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