XX CONTENTS. 



CHAPTER PAGE 



LIX. DISCOVERY BY MEANS OF NEW OR IMPROVED METHODS 



OF INTELLECTUAL OPERATION 606 



LX. DISCOVERY BY MEANS OF CALCULATIONS BASED UPON 



KNOWN TRUTHS . , 607 



INDEX , 613 



Errata. 



Page 77, 13th line from bottom, for manuscript that read manuscript which. 

 195, 3rd line from bottom, for phenomenon read phenomena. 

 196, 13th line from bottom, for strongest read boldest. 



