438 DOCUMENT 377 MARCH 1912 geht, auch dass Marie ein Bübchen (?) bekommt, von dem ich übrigens ja im- merhin so eine Art Onkel bin.[14] Vero will ich ein kleines Buch mit Anleitung zu schönen Versuchen senden.[15] Du musst Ihm aber etwas dazu helfen. Seid herzlich gegrüsst von Euerm Albert. [...][16] ALSX. [7 066]. [1]The year is provided by the reference to Einstein's paper. [2]See Einstein 1912d (Vol. 4, Doc. 4), submitted six days earlier (see Doc. 375). The fol- lowing summarizes this paper and the preceding one, Einstein 1912c (Vol. 4, Doc. 3). Most of the equations cited below are also in Einstein's "Scratch Notebook" (Vol. 3, Appendix A), [pp. 38-39]. See also the editorial note, "Einstein on Gravitation and Relativity: The Static Field," for a discussion. [3]Should be "Weg." [4]Einstein 1912c, 1912d (Vol. 4, Docs. 3 and 4) both appeared in the Annalen der Physik on 23 May. [5]See Doc. 343, note 3, for more on the difference of opinion between Einstein and Max Abraham. [6]Einstein 1912b (Vol. 4, Doc. 2) appeared the same day this letter was written. See Vol. 4, the editorial note, "Einstein on the Law of Photochemical Equivalence," for a discussion of the paper. [7]Einstein's earlier remarks to Besso on this topic are in Docs. 331 and 354. He had with- drawn a paper on the subject two months earlier (see Doc. 343). See Doc. 313, note 7, and Doc. 344, note 5, for more details. [8]Einstein visited Berlin the third week of April (see Doc. 384). [9]Walther Nernst, Max Planck, Heinrich Rubens, Emil Warburg, Fritz Haber, and Erwin Freundlich. [10]Nernst had published a proof of his heat theorem that was contested by Einstein. See Doc. 364, note 6, for more background, and Doc. 366 for information on Nernst's reaction. [11]Paul Habicht had gilded parts of the "Maschinchen" to prevent contact electricity. See the editorial note, "Einstein's 'Maschinchen' for the Measurement of Small Quantities of Elec- tricity," pp. 51-55. The "Auerstrumpf" or Welsbach mantle, named after Carl Auer von Wels- bach (1858-1929), was a very successful and widely used gas mantle. Habicht apparently concluded that radon gas evaporating from the mantle of a gas lamp in the vicinity of the "Maschinchen" was responsible for spurious ionization. [12]On 9 March 1912 Paul Habicht delivered a lecture to the Schweizerische Physikalische Gesellschaft on the "Maschinchen" (see Habicht, P. 1912). [13]Einstein was to begin a teaching appointment in Zurich in the autumn (see Doc. 341, note 1). [14]Marie Müller-Winteler gave birth to Paul Albert Müller on 8 August 1912. Einstein's reference to himself as "a kind of uncle" is based on the fact that his sister Maja was married to Müller-Winteler's brother, Paul . [15]The book intended for Vero Besso was probably Neuburger 1911, an experimental phys- ics primer, which Einstein mentions in his "Scratch Notebook" (Vol. 3, Appendix A), [p. 57]: "Experimental Physics Book of Delights Albert Neuburger" ("Erg. Exper. Buch Albert Neu- burger"). [16]A postscript by Mileva Einstein-Marid is omitted.