CONTENTS. XY 



Pago 

 With the stage micrometer - 217 

 By the micrometer eye-piece - 218 

 To find the value of the lines in the negative eye-piece micrometer ib. 

 To find the value of the divisions in the positive eye-piece micro- 

 meter - - 220 

 To find the value of each revolution of the screw, or parts of a 



revolution of the same, in the cobweb micrometer 221 



Directions for the use of the eye-piece micrometer - 222 



To use the cobweb micrometer - - 223 

 Measurements of an object made by means of a stage micrometer 



and a camera lucida - - - ib. 



CHAPTER IV.A. 



Ok the Methods of Obtadsistq the Magnifying Power of 



Single and Compound Microscopes - - 225 



To convert Paris lines into English measure - 230 



To convert millimetres into English measure - - - ib. 



CHAPTER V. 



Camera Lucida ..... 230 



Method of using the camera lucida with the microscope - 232 



Uses to which the camera lucida may be applied - - 234 



CHAPTER VI. 



On the Polarization of Light - - - . 236 



Origin of the term - - ib. 



Method of using the polarizing apparatus - - 239 



Cause of the colours of polarized light - - 245 



Advantages of polarized light to the microscopist 250 



CHAPTER Vn. 

 Goniometer - - - 251 



