62 EINSTEIN AS PHYSICS STUDENT and handbooks of the time.[12] But Weber also included several topics on which he had himself worked, using his own published and unpublished results.[13] Marginal comments and queries in Einstein's notes are possibly the earliest record of his interest in the nature of intermolecular forces (see Doc. 37, notes 94 and 101), the subject of his first two published papers (Einstein 1901, 1902a). Beginning in 1900, this topic is mentioned frequently in his letters to Maric (see editorial note, "Einstein on Molecular Forces") and it is possible that some of the changes and marginal com- ments, especially those in pencil or in an ink different from that used for the main text, were added at the time of these letters. At least one change appears to be in Maric's hand (see Doc. 37, note 117). Another surviving set of notes of Weber's course, taken by the mechanical engi- neering student Emil Konrad Teucher (1877-1948),[14] occasionally includes material omitted by Einstein, and in some cases shows characteristic differences: in general, Teucher gives more detailed derivations and diagrams and fuller explanations of experiments, whereas Einstein adopts a leaner style, concentrating on concise state- ments of results. Einstein's notes, as preserved, begin in the middle of the first semester and end shortly before the course did on 27 July 1898.[15] Teucher's notes open with a section on the ideal gas (where thermometry and barometry are also discussed), followed by one on calorimetry. The third section is devoted to heat conduction, one of Weber's research interests. In the course of dis- cussing various methods for determining the coefficient of heat conduction experi- mentally, Weber derives and solves Fourier's heat-conduction equation for the spher- ically symmetric case. Einstein's notes begin at this point. [12] See, e.g., Wüllner 1896, 1897 Winkelmann 1893b, 1896. [13] Weber did basic research on heat con- duction, the anomalous temperature depen- dence of certain specific heats, and the energy distribution law for black body radiation he did applied research on AC circuits, electrical lighting, and the standardization of electrical units (see Weiss 1912). For an account of Weber's activities during the 1897-1898 aca- demic year, see his "Bericht über die Thätig- keit der Abtheilungen des physikalischen In- stituts. . .während des Schuljahrs 1898" (SzZE Schulratsarchiv, 1899). For evidence of Ein- stein's familiarity with Weber's research on heat conduction, see Doc. 111. [14] Teucher's notes (SzZE Bibliothek, Hs 32) are the only other known record of Weber's physics course for 1897-1898. Sig- nificant differences between Einstein's and Teucher's notes are annotated. [15] Omitted from Einstein's notes are the topics at the end of the course: the theory of the galvanometer, its use in measuring the earth's magnetic field, and the electrical equiv- alent of heat. Einstein was clearly aware of the topics covered in the early part of the course (see Doc. 39) the extant notes start on the first page of a notebook, and it is possible that notes for the beginning of the course were recorded elsewhere.