vi PREFACE 



the Microscope ' constitute one of the most lucid expo- 

 sitions of the subject which is available, and from which 

 some illustrations, and many suggestions in the text have 

 been taken. 



Lastly, to the various members of the optical trade, 

 both English and Continental, from whom a number of 

 illustrations have been borrowed, thanks are also tendered. 

 In all cases these have been readily supplied, and informa- 

 tion has been given without stint. The author ventures to 

 express the hope that the book may be of assistance to 

 some struggling with the initial difficulties of the subject ; 

 and that it may induce others to enter a field of work 

 which is still not fully explored, and which has almost 

 infinite possibilities, whether considered as a study in itself, 

 or as a means of placing on record the work of others. 



J. E. B. 



LONDON: March 1911. 



