Vlll 
CONTENTS. 
SECTION PAGE 
101. Polarization produced by Double Refraction, 77 
102. Nicol’s Single Image Prism, 77 
103. Common and Polarized Light Contrasted, 79 
Theory of Polarized L.iglit. 
104. Undulatory Theory, 79 
105. Illustrations of wave motion, 80 
106. Polarization illustrated by resultant motion, 81 
107. Polarizing effect of Iceland Spar, 82 
108. Familiar Illustrations, 83 
109. Partial Polarization, 83 
Polarized I^iglit applied to the Microscope. 
110. Polarizing Apparatus, 85 
111. Tourmaline Plates, 86 
112. Herapathite, 87 
113. Value of Polarized Light in Microscopic Investigations, 87 
114. Colored Polarization, 87 
115. Cause of Colors produced by plates of selenite, 88 
116. Method of Varying Colors, 88 
117. Selenite Stage, 90 
118. Polarizer with Revolving Selentine Cai-rier, 90 
119. Delicate structures viewed by colored polarized light, 91 
120. List of Objects for Polariscope, 92 
CIIAPTEK Y. 
PRACTICAL DIRECTIONS. 
121. Care of the Microscope, 94 
122. Illumination, 95 
123. Choice of a Microscope, 95 
124. Qualities of Object-Glasses, 96 
1. Defining power, 96 
2. Resolving power, 97 
Method of measuring angular aperture, 97 
3. Flatness of field, 97 
4. Depth or Extent of Definition, 97 
PRICE LIST, 99 
