viii CONTENTS. 



PART I. continued. 



CHAP. PAGE 



X. THE OPTICAL POWER OF THE MICROSCOPE 90-101 



1. DEFINING AND PENETRATING POWER ACCORD- 

 ING TO THE EARLIER AUTHORS 91, 92 



2. IMPORTANCE OF THE ANGLE OF APER- 

 TURE 93 97 



3. FUSION OF THE INTERFERENCE AND 



DIOPTRIC IMAGES 98, 99 



4. RATIO OF APERTURE AND FOCAL LENGTH 99101 



XL DIFFRACTIONAL ACTION OF THE APERTURE OF THE 



LENSES 102, 103 



XII. ILLUMINATION 103 115 



1. ILLUMINATION BY TRANSMITTED LIGHT... 104 111 

 2. ILLUMINATION BY REFLECTED LIGHT ... Ill 115 



PART II. 

 THE MECHANICAL ARRANGEMENT OF THE MICROSCOPE. 



I. GENERAL RULES FOR THE CONSTRUCTION OF 



STANDS 116 121 



II. THE STANDS OF MODERN OPTICIANS 122 125 



PART III. 

 TESTING THE MICROSCOPE. 



I. TESTING OF THE OPTICAL POWER IN GENERAL ... 126 149 



1. ABSOLUTE POWER OF DISCRIMINATION : 



Images of Wire-gauze as Test-objects 127 132 



Organic Test-objects 132139 



Nobert's Test-plate 139, 140 



2. RELATIVE POWER OF DISCRIMINATION ... 140147 

 3. DEFINING POWER 148, 149 



II. TESTING THE SPHERICAL ABERRATION 149158 



III. TESTING THE CHROMATIC ABERRATION 158167 



IV. TESTING THE FLATNESS OF THE FIELD OF VIEW 168, 169 



V. TESTING THE CENTERING 170, 171 



VI. DETERMINATION OF THE ANGLE OF APERTURE ... 172177 



VII. DETERMINATION OF THE MAGNIFYING POWER 



AND FOCAL LENGTH 178183 



1. MAGNIFYING POWER 178181 



2. FOCAL LENGTH 181 183 



VIII. DETERMINATION OF THE CARDINAL POINTS... 184188 



