CHAPTER I. 



MICROSCOPES AND THEIR MANAGEMENT. 



POWERS THAT ARE MOST SERVICEABLE— ESTIMATED BY 

 FOCAL LENGTH— LENGTH OF BODY OF MICROSCOPK AND ITS 

 EFFECTS— POPULAR ERRORS ABOUT GREAT MAGNIFICATION 

 —MODES OF STATING MAGNIFYING POWER— USE OF AN 

 "ERECTOR"— POWER OF VARIOUS OBJECTIVKS WITH DIF- 

 FERENT EYE-PIECES— EXAMINATION OF SURFACE MARKINGS 

 —METHODS OF ILLUMINATION-DIRECT AND OBLIQUE LIGHT 

 —STAGE APERTURE— DARK GROUND ILLUMINATION— MODE 

 OF SOFTENING LIGHT— MICROSCOPE LAMl'S-CARE OF THE 

 EYES. 



