102 BELL SYSTEM TECHNICAL JOURNAL 



The Compound MicROscoPii 



It is obvious that a complete technical discussion of the instrument 

 and equipment used in photomicrography is not within the scope of 

 this paper nor would it be of interest to many readers. In order to 

 appreciate the possibilities of technical microscopy as an aid in the 



Bvrpuce 



A tagn ififd Virfua/L^ 



Fig. 1 — Optical Diagram of the Compound Microscope. 



solution f)f definite engineering problems relating to telephone ap- 

 paratus it is necessary, howe\er, to consider more in detail the equip- 

 ment used. 



The optical system of the compound microscope is shown diagrani- 

 matiralh- in Kig. 1, and in Figs. 2 and 3 arc pictured two modern 

 re]iresentati\e research t>pe microscopes. In the diagram three 

 parallel pencils of light are shown reflected upward into the condenser 

 which b\- ])roper focusing is caused to illuminate a transparent object 

 (suitably prepared and mounted as described later) placed in |)osi- 

 tion on the microscope stage. As shown the objective would form 



