According to the theory of relativity the displacement of the lines should be $+0.0080 A$. St. John at Mt. Wilson found a displacement for the cyanogen lines of only $+0.0018 A$.16 Evershed at Kodaikanal found +0.0060 at the north pole of the sun, and +0.0080 at the south pole. These latter values however were only for the stronger lines. The weaker lines give much smaller shifts, as do those of calcium and magnesium.17 According to Einstein all lines should give nearly the same shift, an amount proportional to the wave length. It therefore appears that we must conclude by saying that Einstein's theory of relativity has been partially, but not completely, verified. The reference numbers in the above text have nothing to do with the numbers used in other parts of this volume to acknowledge the work of the various contestants; they refer to Dr. Pickering's sources, as follows: 1 Journ. Brit. Astron. Assoc., 1919, 30, 76. 2 Comptes Rendus, 165, 424, and 167, 71. 3 Monthly Notices R. A. S., 1919, 80, 104. 4 Monthly Notices R. A. S., 1917, 77, 379. 5 Astro-Physical Journal, 1917, 46, 249. Journ. Brit. Astron. Assoc., 1920, 30, 276. 6 Monthly Notices, R. A. S., 1917, 77, 377. 7 Amer. Journ. Sci., 34, 333. 8 Monthly Notices, R. A. S., 1920, 80, 628. 9 The Observatory 1920, April. From an Oxford Note Book. 10 Monthly Notices, R. A. S., 1917. 78, 3 De Sitter, 1919, 80, 121, Jeans, 80, 146 Jeffreys. 11 "Gravitation and the Principle of Relativity," Eddington. Royal Institution of Great Britain, 1918. 12 Journ. Brit. Astron. Assoc., 1920, 30, 125. 13 "The Interior of a Star," Eddington. Scientia, 1918, 23, 15. 14 Monthly Notices, R. A. S., 1919, 80, 138. 15 Monthly Notices. R. A. S., 1920, 80, 415. Journ. Brit. Astron. Assoc., 1919, 30, 46. 16 Astro-Physical Journ., 1917, 46, 249. 17 Journ. Brit. Astron. Assoc., 1920, 30, 276. XVIII THE PRACTICAL SIGNIFICANCE OF RELATIVITY The Best Discussion of the Special Theory Among All the Competing Essays BY PROFESSOR HENRY NORRIS RUSSELL, PRINCETON UNIVERSITY Can a small child catch a baseball moving sixty miles an hour without getting hurt? We should probably answer "No"--but suppose that the boy and his father were sitting side by side in an express train, and the ball was tossed lightly from one to the other. Then there would be no trouble about it, whether the train was standing still, or going at full speed. Only the relative motion of ball and boy would count.