LIST OF WOOD-CUT ILLUSTRATIONS. 



1. Diagram illustrating Refraction 2 



2. Refraction of parallel rays by plano-convex lens .... 4 



3. Ditto by double-convex lens ... 5 



4. Refraction of rays diverging from distance of diameter . . 6 



5. Refraction of Diverging Rays 7 



6. Refraction of Converging Rays 7 



7. Formation of images by Convex lenses 9 



8. Spherical Aberration 9 



9. Chromatic Aberration 12 



10. Section of Achromatic Object-glass 14 



11. Effect of Covering-glass 17 



12. Action of Simple Microscope 19 



13. Simplest form of Compound Microscope 24 



14. Complete Compound Microscope 24 



15. Huyghenian Eye-piece 25 



16. Stereoscopic Pyramids 29 



17. Arrangement of Prisms in Nachet's Stereoscopic Binocular 



Microscope 31 



18. Nachet's Stereoscopic Binocular 32 



19. "Wenham's Prism for Stereoscopic Binocular 33 



20. Sectional view of Wenham's Stereoscopic Binocular ... 34 



21. Exterior view of Wenham's Stereoscopic Binocular ... 34 



22. Arrangement of Prisms in Nachet's Stereo-Pseudoscopic Bino- 



cular 35 



23. Exterior of Nachet's Stereo-Pseudoscopic Binocular ... 36 



24. Diagram illustrating Angle of Aperture suitable for Binocular 



Objectives 38 



25. Ditto Ditto 39 



26. Ross's Simple Microscope 47 



27. Gairdner's Doublet Microscope 49 



28. Field's Simple Microscope 51 



29. Quekett's Dissecting Microscope 5 



30. Beck's Dissecting Microscope, with Nachet's Binocular Magnifier 53 



31. Field's Educational Microscope 58 



32. Crouch's Educational Microscope 60 



33. Pillischer's Student's Microscope 62 



34. Murray and Heath's Student's Microscope 63 



35. Smith and Beck's Student's Microscope 65 



36. Ladd's Student's Microscope 67 



37. Nachet's Student's Microscope 69 



38. Crouch's Student's Binocular 72 



39. Collins's Harley Binocular 75 



40. Beale's Demonstrating Microscope 83 



41. Baker's Travelling Microscope 4 



42. Dr. Lawrence Smith's Inverted Microscope ^5 



