OF THE 



UNIVERSITY 



OF 



PREFACE TO SECOND EDITION. 



The demand for this book having considerably 

 exceeded the expectations of its author, and the com- 

 ments on its utility having been so favorable, lead to 

 the view that it fills a gap in microscopical literature. 



In preparing for a new edition an opportunity has 

 been given for enlarging on some of the subjects and 

 rewriting others, so as to make them conform to the 

 changes which the last five years have brought about 

 in the construction of apparatus. 



While it may be true that many of the subjects 

 might be treated much more extensively, the writer has 

 purposely refrained from doing so, because he has con- 

 sidered it beyond the province of his intention, and 

 because books giving more extensive information are 

 available. 



An intending purchaser of a microscope finds it 

 more or less difficult to make a suitable selection and, 

 while it is always best to consult an experienced 

 microscopist, the writer has endeavored to convey 

 information which, he hopes, will aid in this direction. 



THE AUTHOR. 

 May, 1891. 



in 



