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XV. Aberration Problems.—A Discussion concerning the Motion of the Ether near 
the Earth, and concerning the Connexion bettveen Ether amd Gross Matter; with 
some new Exigeriments. 
By Oliver J. Lodge, F . R . S , 
Received and Read MarcK 31, 1892.—Revised July 17, 1893. 
[Plates 31, 32.] 
Table of Contents. 
Page. 
Section 1. Statement of problem. 729 
2. Meaning of free and modified ether. 729 
3. Meaning of travel of modified ether. 730 
4. Fresnel’s hypothesis. 731 
5. Expression in terms of electromagnetic constants. 732 
6. J. J. Thomson’s hypothesis. 732 
7. Verification of one part of Fresnel’s law. 733 
8. Attempted verification of the other part . 734 
9. Summary of phenomena resulting from motion. . . 735 
10. Projectile analogies. 735 
11. Effect of motion on waves, magnetic lines of force, &c. 736 
12. Frequent convenience of attributing motion to medium. 738 
13. Fixed source in moving medium. 738 
14. Moving source in fixed medium. 740 
15. Medium moving past fixed source and receiver. 741 
16. Modes of observing interference effects due to motion. 742 
17. Influence of dense bodies inserted in path. 742 
18. Modes of observing effect of motion on intensity. 743 
19. Criticism of the suggested experiment. 744 
20. Receiver only moving, effect on focussing. 745 
21. Summary of conclusions so far reached. 747 
22. No method of detecting first-order effects of ethereal motion exists .... 747 
23. Treatment by principle of least time. 748 
24. Irrotational motion of homogeneous medium causes no first-order effects . . 748 
25. First discussion of Mr. Michelson’s experiments. Extraordinary result . . 749 
26. Contradictory result supposed to be obtained by Fizeatj’s polarization experi¬ 
ment .. 760 
27. Summary of statements concerning rays and wave-normals in an irrotationally 
moving medium. Line of vision depends only on motion of observer . . 750 
28. In a non-homogeneous medium, motion such that cos 6 is constant or is the 
derivative of a potential function, will cause no first-order effects .... 751 
25.10.93 
