CONTENTS 
ACHROMATIC MICROSCOPES. 
CHAPTEE 1. 
THEORY OF THE MICROSCOPE. 
SECTION PAGE 
1. Introduction, 1 
2. Simple Lenses, 1 
3. Foci of Lenses, 1 
4. Aberration, 2 
5. Spherical Aberration, 2 
6. Amount of Spherical Aberration, 3 
7. Proportionate Curvature, 4 
8. Negative Aberration, 4 
9. Aberration of Sphericity : Curvature of Image, 4 
10. Chromatic Aberration, 5 
11. First method of diminishing Chromatic Aberration, 6 
12. Second “ “ “ “ “ 6 
13. Achromatism, 6 
14. Combined Lenses, 7 
15. Angular Aperture, 8 
16. Oblique Illumination, 9 
17. Lister’s Discoveries, 9 
18. Essential requisites of good Object-Glasses, 9 
19. Mr. Lister’s two Preliminary Propositions, 10 
20. Principles discovered by Mr. Lister, 10 
21. Aplanatic Object-Glasses, 11 
22. Superiority of English and American Object-Glasses, 12 
23. Compound Achromatic Microscope, 12 
24. Positive Eye-piece, 12 
25. Negative Eye-piece, 12 
26. General view of Compound Achromatic Microscopes, 13 
27. Enlarged section of Achromatic Microscope, 15 
28. Action of Negative Eye-piece, 16 
29. Advantage of Over-correcting Object-Glass, 17 
30. Negative Eye-piece nearly Achromatic, 17 
31. Use of the term Achromatic Objective, 18 
32. Aberration produced by Glass Cover, 19 
33. Objective Corrected for Glass Cover, 20 
34. Eye-pieces of different Powers, 21 
