CONTENTS. 



CHAPTER I. The Interferences of Crossed Spectra. 



PAGE 



1 . Introductory 7 



2. Coincident spectra with one reversed on a given Fraunhofer line. Figs. I, 2, 3 . . 8 



3. The same. Further experiments 1 1 



4. Coincident spectra with one reversed on a given longitudinal axis. Figs. 4, 5, 6. . 12 



5. Interference of the corresponding first-order spectra of the grating, in the absence 



of rotation. Figs. 7, 8, 9, 10 14 



6. Conclusion 16 



CHAPTER II. Further Study of the Interference of Reversed Spectra. 



7. Apparatus with one grating. Figs. 1 1, 12, 13, a, b 19 



8. Observations and experiments with a single grating. Fig. 14 22 



9. Inferences. Fig. 15, a, b 24 



10. Apparatus with two gratings. Figs. 16, 17, 18 26 



11. Experiments continued. New interferometer. Figs. 19, 20 30 



12. Experiments continued. Homogeneous light 32 



13. Experiments continued. Contrast of methods 33 



14. Experiments continued. Rotation, etc., of grating. Figs. 21, 22 33 



15. Tentative equations. Figs. 23, 24, 25 36 



16. Experiments continued. Analogies. Figs. 26, 27 38 



17. Subsidiary diffractions. Figs. 28, 29 43 



18. Conclusion 45 



CHAPTER III. The Interferences of Non-reversed Spectra of Two Gratings. 



19. Introduction. Method. Figs. 30, 31 46 



20. White light. Colored fringes. Tables i, 2, 3. Figs. 32, 33, 34, 35 47 



21. Homogeneous light. Wide slit. Transverse axes coincident. Tables 4, 5. Fig. 36.. 52 



22. Homogeneous light. Fine slit. Transverse axes not coincident. Table 6. Fig. 37. 54 



23. Homogeneous light. Slit and collimator removed. Table 7. Fig. 38 55 



24. Inferences. Figs. 39, 40 56 



25. Rotation of colored fringes. Non-reversed spectra. Figs. 41, 42 58 



26. Final treatment of reversed spectra. Hypothetical case. Figs. 43, 44, 45, 46 .... 60 



27. Case of reflecting grating. Homogeneous light. Figs. 47, 48 64 



28. Non-symmetrical positions. Fore-and-aft motion. Fig. 49 67 



CHAPTER IV. The Distance Between Two Parallel Transparent Plates. 



29. Introductory 69 



30. Apparatus. Figs. 50, 51 69 



31. Equations. Figs. 52, 53 70 



32. Method 72 



33. Observations and corrections. Preliminary work. Figs. 54, 55 73 



CHAPTER V. Interferometers for Parallel and for Crossed Rays. 



34. Introduction. Methods. Figs. 56, 57 78 



35. Experiment. Reflecting grating. Parallel rays. Fig. 58 79 



36. Experiments. Transmitting grating. Parallel rays 81 



37. Experiments. Transmitting grating. Crossed rays. Figs. 59, 60, 61, a, b 82 



38. The same. The linear phenomenon. Fig. 62 85 



39. The same. Inferences. Figs. 63, 64, 65 87 



40. Experiments. Reflecting grating. Crossed rays. Figs. 66, 67 88 



41. The same. Compensators 91 



42. Miscellaneous experiments. Fringes with mercury light 91 



43. Inferences. Figs. 68, 69 92 



3 



