viii PREFACE. 



point the way to success to those who are ignorant of 

 the sciences they aspire to master, and who have no 

 friend to help or coach them, that these volumes arc 

 written. 



To those who have worked hard to place simply and 

 clearly before the reader that which he will find within, 

 the best thanks of the Editor are due. That it has been 

 no slight labour to supervise all that has been written 

 he must acknowledge ; but it has been a labour of love, 

 and very much lightened by the courtesy of the Publisher, 

 by the unflinching, indefatigable assistance of the Sub- 

 Kditor, and by the intelligent and able arrangement 

 of each subject by the various writers, who are so 

 thoroughly masters of the subjects of which they treat. 

 The reward we all hope to reap is that our work may 

 prove useful to this and future generations. 



THE EDITOR. 



