CONTENTS. 



PAGH 



Introduction 2 



CHAPTER I. 



Disks of Glass for Optical Mirrors 1 



CHAPTER II. 



Tlip Optical Laboratory of the Yerkes Observatory 2 



CHAPTER III. 

 Grinding and Polishing Machines 3 



CHAPTER IV. 

 Grinding Tools g 



CHAPTER V. 

 Polishing Tools 7 



CHAPTER VI. 



Rough-grinding the Face and Back of a Rough Disk of Glass, and Making the Same 



Parallel 10 



CHAPTER VII. 



Grinding Edge of Glass. — Rounding of Corners 11 



CHAPTER VIII. 



Fine-grinding and Polishing the Back of the Mirror 13 



CHAPTER IX. 



(Trinding the Concave Surface 14 



CHAPTER X. 



Polishing 17 



CHAPTER XI. 



Testing ami Figuring Splicrical Mirrors 21 



iii 



