The increase of mass was the first prediction of Lorentz and Einstein to be tested, but some experiments by Kaufmann appeared to show a slightly different mass increase; this led Lorentz to the famous remark that he was "au bout de mon latin" ("at the end of my [knowledge of] Latin" = at his wit's end) The confirmation of his prediction had to wait until 1908 and later (see Kaufmann–Bucherer–Neumann experiments).
The increase of mass was the first prediction of Lorentz and Einstein to ,be tested but some experiments by Kaufmann appeared to show a slightly different mass increase; this led Lorentz to the famous remark that he was "au bout de mon latin" ("at the end of my [knowledge of] Latin" = at his wit's end) The confirmation of his prediction had to wait until 1908 and later (see Kaufmann–Bucherer–Neumann experiments).