OBJECTIVES AND EYEPIECES. 



Objectives; Tube Length; Nomenclature, or Rating of 

 Objectives; Powers; Systems; Angular Aperture ; Cover 

 Glass; How to Measure Angular Aperture; Resolving 

 Power; Chromatic Aberration ; Spherical Aberration and 

 Cover Glass; Penetration; Flatness of Field; Working- 

 Distance; To Measure Working Distance; Magnifying 

 Po\ver; Apochromatic Objectives; Eyepiece or Ocular; 

 Huyghenian Eyepiece; Solid Eyepiece; Ramsden Eye- 

 piece; Periscopic, Orthoscopic and Kellner Eyepieces; 

 Compensating Eyepiece; Rating or Designation; Flat- 

 ness of Field; Size of Field; Defects. 



HOW TO WORK. 



To Attach Eyepiece; To Attach Objective; Finding an 

 Object; To Illuminate the Object; How to Focus; Which 

 Eye to Use; What Objects to Use; Test Plate; How to 

 Work; Opaque Object; Medium Power of Objective; 

 Chromatic Aberrations; Cover Glass; Dry Adjustable 

 Objectives; Immersion Objectives; Immersion. Objec- 

 tives on Test Plate. 



ILLUMINATION WITH CONDENSER. 



Purpose of the Condenser; Abbe Condenser; Centering; 

 Centering the Illumination; To Focus Condenser; Rela- 

 tion of Aperture of Condenser to Objective; Oblique 

 Light with Condenser. 



