Kaufmann (1903) presented results of his experiments on the charge-to-mass ratio of beta rays from a radium source, showing the dependence of the velocity on mass. He announced that these results confirmed Abraham's theory. However, Lorentz (1904a) reanalyzed results from Kaufmann (1903) against his theory and based on the data in tables concluded (p. 828) that the agreement with his theory "is seen to come out no less satisfactory than" with Abraham's theory. A recent reanalysis of the data from Kaufmann (1903) confirms that Lorentz's theory (1904a) does agree substantially better than Abraham's theory when applied to data from Kaufmann (1903). Kaufmann (1905, 1906) presented further results, this time with electrons from cathode rays. They represented, in his opinion, a clear refutation of the relativity principle and the Lorentz-Einstein-Theory, and a confirmation of Abraham's theory. For some years Kaufmann's experiments represented a weighty objection against the relativity principle, although it was criticized by Planck and Adolf Bestelmeyer (1906). Other physicists working with beta rays from radium, like Alfred Bucherer (1908) and Günther Neumann (1914), following on Bucherer's work and improving on his methods, also examined the velocity-dependence of mass and this time it was thought that the "Lorentz-Einstein theory" and the relativity principle were confirmed, and Abraham's theory disproved. Kaufmann–Bucherer–Neumann experiments A distinction needs to be made between work with beta ray electrons and cathode ray electrons since beta rays from radium have a substantially larger velocities than cathode-ray electrons and so relativistic effects are very substantially easier to detect with beta rays. Kaufmann's experiments with electrons from cathode rays only showed a qualitative mass increase of moving electrons, but they were not precise enough to distinguish between the models of Lorentz-Einstein and Abraham. It was not until 1940, when experiments with electrons from cathode rays were repeated with sufficient accuracy for confirming the Lorentz-Einstein formula. However, this problem occurred only with this kind of experiment. The investigations of the fine structure of the hydrogen lines already in 1917 provided a clear confirmation of the Lorentz-Einstein formula and the refutation of Abraham's theory.