IV CONTENTS. 



TESTING OBJECTIVES. 



General Rules ; Accepted Standards Diatoms, Ruled Lines, Arti- 

 ficial Star; Podura ; Nobert's Lines; Holler's Probe Platte; Table 

 of Diatoms on Holler's Probe Platte, with the Number of Lines 

 to the Inch on the Several Diatoms ; Hethods of Testing for Flat- 

 ness of Field, Penetration, etc., 84 



SELECTION OF A MICKOSCOPE FOB PRACTICAL PURPOSES. 



Must be Adapted to Requirements and Skill of User; Microscopes 

 for Botany ; For Physicians ; For Students ; Magnifying Power 

 Required ; The Stand ; The Stage ; Mechanical Stages ; Revolving 

 Stage ; Stages for Special Purposes ; Diatom Stage, Safety Stage, 

 etc.; Sub-Stage; Mirror; Body; Draw-Tube; Adjustments for 

 Focussing; The Diaphragm; Objectives; High versus Low 

 Angles ; Eye-Pieces, - 95 



ACCESSORY APPARATUS. 



Stage Forceps; Forceps Carrier; Object Holder < Plain Slides; 

 Concave Slides ; Watch-Glasses ; Watch-Glass Holder* Animal- 

 cule Cage; Large Zoophyte Trough- Small Zoophyte Trough; 

 Walmsley's Zoophyte Trough; The Weber Slide; The Cell- 

 Trough ; The Compressorium > Gravity Compressorium ; Grow- 

 ing Slides ; Frog Plate ; Table ; Double Nose-piece, - 127 



ILLUMINATION SOURCES OF LIGHT. 



Sun-Light; Artificial Light Candles, Gas, Lamps, Magnesium, 

 Oxyhydrogen Light ; Parallel, Convergent and Divergent Rays, 143 



ILLUMINATION OF OPAQUE OBJECTS. 



Diffused Light ; Bulls-Eye Condenser ; Side Reflector ; The Lieber- 

 kuhn ; The Parabolic Reflector ; Objectives with Tapered Fronts ; 

 Smith's Vertical Illuminator; Tolles' Vertical Illuminator. - 147 



ILLUMINATION OF TRANSPARENT OBJECTS. 



Direct and Reflected Light; Axial or Central Light; Oblique 

 Light ; The Achromatic Condenser ; The Webster Condenser, and 

 How to Use it ; Wenham's Reflex Illuminator, and How to Use 

 it ; The Wenham Prism ; The Hemispherical Illuminator ; The 

 " Half Button " ; The Woodward Illuminator ; Tolles' Illumina- 

 ting Traverse Lens ; The Spot Lens ; The Parabolic Illumina- 

 tor ; Polarized Light, - - - - 152 



How TO USE THE MICROSCOPE. 



General Rules ; Simple Hand Magnifiers ; Compound Microscopes ; 

 Practical Notes on Illumination; White Cloud Illumination; 

 Monochromatic Light ; Blue Cell ; Opaque Objects ; Hints to Be- 

 ginners, - - 164 



How TO USE OBJECTIVES OF LARGE APERTURE. 

 Illumination ; Collar-Correction for Cover-Glass, - - - 171 



