PREFACE 



TO 



THE SIXTH EDITION. 



THE fifth edition of the * Correlation of Physical Forces ' 

 having been exhausted, I have done my best during 

 the few spare hours at my disposition to prepare a 

 sixth. Partly induced by the suggestions of others, 

 partly, perhaps, by egotism, I have added a selection 

 of papers on scientific subjects, which I have from 

 time to time previously published. Physical science 

 has moved on far too quickly for me to follow it, and 

 no one is more convinced than I am that 



To have done, is to hang 

 Quite out of fashion, like a rusty mail, 

 In monumental mockery. 



Still, having gone through my past contributions to 

 science, forgotten by all others, half-forgotten by my- 

 self, I find something of suggestion in most of them 

 which may not be altogether useless ; and as the papers 

 are scattered about in various periodicals, a collection 

 of them in one volume may be accepted as a last 

 legacy. 



