On January 5, 1845, the Prussian cultural minister received a request by a group of six young men to form a new Physical Society in Berlin. In fields from thermodynamics, mechanics, and electromagnetism to animal electricity, ophthalmology, and psychophysics, members of this small but growing group--which soon included Emil Du Bois-Reymond, Ernst Br cke, Werner Siemens, and Hermann von Helmholtz--established leading positions in what only thirty years...