Editor's Introduction. The Hanging Chain: A Forgotten 'Discovery' Buried in Galileo's Notes on Motion; J. Renn, P. Damerow. The Chymical Laboratory Notebooks of George Starkey; W. Newman, L.M. Principe. Newton's Optical Notebooks: Public Versus Private Data; A.E. Shapiro. At Play with Nature: Luigi Galvani's Experimental Approach to Muscular Physiology; M. Bresadola. The Practice of Studying Practice: Analyzing Laboratory Records of Ampère and Faraday; F. Steinle. From Agents to Cells: Theodor Schwann's Research Notes of the Years 1835-1838; O. Parnes. Narrating by Numbers: Keeping an Account of Early 19th Century Laboratory Experiences; O. Sibum. Exploring Contents and Boundaries of Experimental Practice in Laboratory Notebooks: Samuel Pierpoint Langley and the Mapping of the Infra-red Region of the Solar Spectrum; A. Loettgers. The Pocket Schedule. Note-Taking as a Research Technique: Ernst Mach's Ballistic-Photographic Experiments; C. Hoffmann. From Lone Investigator to Laboratory Chief: Ivan Pavlov's Research Notebooks as a Reflection of His Managerial and Interpretive Style; D.P. Todes. Carl Correns' Experiments with Pisum, 1896-1899; H.-J. Rheinberger. Errors and Insights: Reconstructing the Genesis of General Relativity from Einstein's Zurich Notebook; J. Renn, T. Sauer. Hans Krebs' and Kurt Henseleit's Laboratory Notebooks and Their Discovery of the Urea Cycle: Reconstructed with Computer Models; G. Graßhoff, M. May. Laboratory Notebooks and Investigative Pathways; F.L. Holmes.