CONTENTS. Vll 
SECTIOS 
68. Dr. White’s Micrometer, 49 
69. Prof. J. Lawrence Smith’s Goniometer and Micrometer, 60 
70. Method of using the Goniometer, 51 
71. Value of Lines in Eye-piece Micrometers, 51 
72. Method of using the Micrometer, 53 
73. Fraunhofer’s Stage-Screw Micrometer, 54 
Camera Cacida. 
74. Wollaston’s Camera Lucida, 56 
75. Nachet’s Camera Lucida, 56 
76. Soemmering’s Steel Speculum, 57 
77. Using the Camera, 57 
78. Camera Lucida applied to Micrometry, 58 
■Tli§cellasaeou§ Apparatus. 
79. Movable Diaphragm Plate, 58 
80. Bull’s-Eye Condenser, 59 
81. Smaller Bull’s-Eye Condenser, 60 
82. Achromatic Condenser, 61 
83. Nachet’s Prism for Oblique Illumination, 62 
84. Lieberkuhn Speculum, 63 
85. Erector, 64 
86. Orthoscopic Eye-piece, 64 
87. Compressor, 65 
88. Animalcule Cage with Screw, 65 
89. Simple Animalcule Cage, 66 
90. Stage Forceps : Hand Forceps, 66 
91. Frog Plate, 66 
92. Machine for cutting circles of thin glass, 67 
93. Instrument for making cells of gold size, 69 
CHAPTER lY. 
POLARIZED LIGHT AND ITS APPLICATION TO THE 
MICROSCOPE. 
94. Theories of Light, 70 
95. Double Refraction and Polarized Light, 70 
96. Polarization by Reflection, 71 
97. Polarization by Refraction, 72 
98. Polarization by bundles of thin plates, 74 
99. Double Refraction, 74 
100. Double Refraction of Iceland Spar, 75 
