PREFACE TO THIRD EDITION. 



The past demand for this little volume makes 

 extended remarks superfluous, the new edition appear- 

 ing as evidence that it is considered of some value. 



This edition has been almost entirely rewritten to 

 bring it in accord with the advance which has been 

 made in the construction of microscopes -and acces- 

 sories and while it is not expected to be a complete 

 guide, it is, nevertheless, hoped that it will lighten 

 the labor of the beginner. 



Since its first issue there have appeared two books 

 covering the same purpose: " The Microscope and 

 Microscopical Methods " by Prof. S. H. Gage of 

 Cornell University and " Microscopical Praxis " or 

 " Simple Methods of Ascertaining the Properties of 

 Various Microscopical Accessories" by Dr. A. C. Stokes, 

 both of which are heartily commended to the micro- 

 scopist. Neither should be wanting in a microscopical 

 library. The writer is also pleased to acknowledge the 

 suggestions of an enlarged scope for this book, which 

 he has obtained by a perusal of them, as well as from 

 the admirable work of Dr. W. H. Dallinger in the 

 latest issue of Carpenter, " The Microscope and its 

 Revelations ", which may be commended to those who 

 wish to study more deeply the principles of the micro- 

 scope and learn its history and development. 



