CONTENTS. 



CHAPTER I. Elliptic Interferometry Applied to the Horizontal Pendulum. 

 PART I. Direct Differential Reflection. 



PAGE 



1. Introduction. Method. Fig. i I 



2. Equations. Figs. 2,3,4 2 



3. Observations. Fig. 5 6 



4. New apparatus, without float. Figs. 6, 7 7 



5. Observations. Fig. 8 9 



6. New apparatus, with float. Horizontal pivots 1 1 



7. Observations. Figs. 9, ioa, io 12 



8. Second apparatus, with float. Jeweled bearings. Fig. no, lib, lie 14 



9. Observations. Fig. 12 15 



10. Observations, continued. Fig. 13 17 



1 1 . Effect of temperature on the float, etc 18 



12. Further observations. Fig. 14 20 



13. Effect of temperature on the scaffolding. Fig. 15 21 



14. Inferences. Fig. 16 24 



15. The precision measurement of elongations. Fig. 17 25 



16. Improved pendulum 28 



17. Observations with the new pendulum. Fig. 18 28 



PART II. An Application of the Displacement Interferometer to the Horizontal 



Pendulum. 



18. Introductory 30 



19. Apparatus. Figs. 19, 20, 21 31 



20. Equations 34 



21. Observations with a grating rotating on a fixed vertical axis 38 



22. Observations with the interferometer. Fig. 22 39 



23. Further observations. Film grating. Oil damper. Figs. 23A, 236, 24, 25, 26 41 



24. Inferences 42 



25. Improved aluminum pendulum. Observations. Fig. 27 45 



CHAPTER II. The Repulsion of Two Metallic Disks, Nearly in Contact. 



26. Apparatus. Figs. 28, 29 49 



27. Equations 50 



28. Equations for the vertical pendulum. Fig. 30 51 



29. Observations with small plates. Figs. 3iA, 316, 3iC, 32A, 328 52 



30. Observations. Plates of larger area. Table r. Figs. 33A, 336, 330, 330 53 



31. The same, continued. Metallic contact. Table 2. Figs. 34A, 346 55 



32. Retardation due to viscosity of air. Table 3. Fig. 35 57 



33. Observations, continued. Presence and absence of electrical contact. Table 4. 



Fig. 36 60 



34. Observations, continued. Change of distance apart. Table 5. Figs. 37, 38, 39A, 



39B 61 



35. Observations. Long periods and inversion. Table 6. Fig. 40 65 



36. Plates electrically charged. Tables 7, 8. Figs. 41 A, 416 67 



37. Conclusion 70 



CHAPTER III. The Refraction of Long Glass Columns Measured by Displacement 



Interferometry. 



38. Introductory 72 



39. Glass columns. Fig. 42 72 



40. Equations 74 



41. Equations. Sensitiveness in terms of displacement 75 



42. Equations. Sensitiveness in terms of order 76 



43. Observations. Green glass column. Table 9 77 



44. Observations. Blue glass column. Table 10 78 



45. Observations. Shorter column. Table 1 1 79 



46. Summary. Fig. 43 80 



v 



