INTRODUCTION. 



This 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 



