( xxxiv ) 



LIST OF WOODCUTS. 



FIGS. PAPERS AND NOTES ILLUSTRATED. PAGE 



1-3— Movements of Diatoms Part 1 107 



4-6 — Bausch and Lomb Optical Company's " Professional " and 



" Investigator " Microscopes „ 111-13 . 



7— Crouch's Histological Microscope „ 114 



8-10— Tolles-Blackham Microscope , 116-18 



11 — Dr. Royston-Pigott's General Transfer Finder „ 119 



12-14 — Secure Method of Setting the Front Lens of Oil-immersion 



Objectives „ 122-3 



15 — Beck's Rotating Holder for Rubber Cells „ 124 



16 — Wallis's Calotte Substage „ 125 



17-18 — Centering Nose-piece as a Substage „ 126 



19 — Mayall's Spiral Diaphragm for Oblique Illumination.. .. „ 127 



20-21 — The Essence of Homogeneous Immersion „ 133 



22-23— Dr. Maddox's Modified Aeroconiscope „ 135 



24— Mounting Clip „ 141 



25-6 — Holman's Compressorium and Moist Chamber „ 142-3 



27-9— Holman's " Life Slide " „ 144-5 



30— Glass Crystals „ 146 



31-3 — Mr. Sliadbolt's Paper on " The Apertures of Microscope 



Objectives" „ 156-8 



34-5 — Mr. Crisp's Paper in reply to same „ 164 



36-8 — Prof. Abbe's Paper on " The Conditions of Orthoscopic and 

 Pseudoscojnc Effects in the Binocular Microscope " 



Part 2—203, 206, 211 



39-41— GrifSth Club Microscope Part 2 293-5 



42-4— Swift's Student's Microscope (Wale's Model) „ 296-7 



45 — Abbe's Stereoscopic Eye-piece „ 298 



46 — Watson's Mechanical and Rotating Stage „ 300 



47 — " Butterfield " Gauge of Screw for Objectives „ 301 



48-9 — Murray and Heath's Polarizing Apparatus „ 302 



50-109 — Mr. Crisp's Paper, " Notes on Aperture, Microscopical 

 Vision, and the Value of Wide-angled Immersion Objec- 

 tives," viz. : — 



I. The Aperture Theories. — Apertures exceeding 180° 

 angular in Air. — The true Notation for Aperture 



(Figs. 50-64) ,,303-26 



II. Angular-Aperture Fallacies (Figs. 65-77) . . . . „ 326-41 



III. Photometrical Questions connected with Aperture 



(Figs. 78-90) „ 341-7 



IV. Microscopical Vision and the Delineating Power of 



Objectives (Figs. 91-109) ,,347-59 



