Klaus Hentschel is Assistant Professor at the Institute for the History of Science at the University of Göttingen and a fellow at the Dibner Institute for the History of Science and Technology, Massachusetts Institute of Technology, for 1996/97.

• Introduction; 1. The young astronomer Erwin Finlay Freundlich; 2. A theorist's observer: Freundlich's collaboration with Einstein from 1911; 3. Relativity theory under scrutiny: experimental testing; 4. Statistical investigations of gravitational redshift, 1915-1916; 5. Berlin science politics: support for Freundlich from 1913; 6. Astrophysics at Potsdam and elsewhere; 7. Erich Mendelsohn and the tower telescope design; 8. Research at the Eistein Tower during the Freundlich era; 9. The solar eclipse expedition of 1929; 10. Clashes between Freundlich and Ludendorff; 11. Political transition and exile; 12. A solitary fate: photon-photon interacti on; 13. A bird's-eye view; Reference matter; Abbreviations in the Notes; Notes; References; Index.

"In this compact and lively study, Hentschel weaves together elements of a story that conventional disciplinary divisions—history of physics, history of architecture, history of institutions—pull asunder. By deliberately focusing not on a theory, a person, or even an institution but rather a building, he is able to skip nimbly among these unusually disjoint subjects and approaches and to create a smooth and often fascinating, always illuminating, narrative out of these pieces."—Lorraine Daston, University of Chicago "Hentschel has succeeded in writing a very readable account of certain hitherto neglected aspects of the early history of general relativity, made more fascinating by the eccentric perspective that his account takes."—Jürgen Renn, Max Planck Institute for the History of Science