INTRODUCTION. 
Tuts little book is intended for the teacher, and the 
beginner with the microscope, not for the specialist. It 
contains very few original data and treats no single sub- 
ject with completeness. 
Almost all the branches of technical microscopy have 
been already made the basis for monographs with which 
the present volume can in no way compete. On the 
other hand, there are many entertaining popular books 
on the microscope which treat it as a mere adjunct to the 
study of natural history. Neither type of work was 
suited for the use of a class in Industrial Microscopy 
which is offered to second-year Chemists and Biologists 
at the Massachusetts Institute of Technology. The 
object of this course is twofold—first, to give facility in 
the manipulation of the microscope; and second, to fur- 
nish an acquaintance with the scope of its practical 
..application. As a text-book there was needed a brief 
and elementary treatise which should take up the funda- 
mentals of the science and art of microscopy itself and 
make a rapid but wide survey of the principal fields in 
which the microscope has been applied to practical 
Vv 
