X PREFACE. 



happens to be the analytical equivalent of the therm o- 

 dynamical formula JCM) ; and one (the " Notes 

 on the President's Address ") was published in Black- 

 wood's Magazine for December 1874. The greater 

 number are now printed for the first time. 



The juvenile verses and translations have been 

 included for the same reason which has led to the 

 prominence given to the early life in Part I. If we 

 are right in our estimate of Maxwell, it must be inter- 

 esting to watch the unfolding of such a mind and 

 character from the first, and this not only for the 

 psychological student, but for all those who share 

 Wordsworth's fondness for "days" that are " linked 

 each to each with natural piety." 



While the last sheets were being revised for the 

 press the sad news arrived that Maxwell's first cousin, 

 Mr. Colin Mackenzie, had died on board the Bosnia, 

 on his way home from America. There was no one 

 whose kind encouragement had more stimulated the 

 preparation of this volume, or whose pleasure in it 

 would have been a more welcome reward. But he, 

 too, is gone before his time, and this book will be 

 sent into the world with fewer good wishes. He 

 deserves to be remembered with affection wherever 

 the name of James Clerk Maxwell is honoured or 

 beloved. 



LEWIS CAMPBELL. 



August 1882. 



