ARL Ludwig's introduction of graphic registration in physiology has C stood for over a century as one of the great landmarks of science (i). Opening as it did a totally new approach to the study of bodily function, creating and establishing whole schools of physiological endeavor, the kymograph he developed was one of the instrumentalities of the great development of scientific medicine in the nineteenth century. Its very importance has reinforced its isolation in the history of medicine, and it has become one of the datemarks to which subsequent development has been referred. It is axiomatic that few discoveries are completely isolated, or spring fully formed and in all originality from the work of a single individual, and one of the duties of history is to trace as well as possible the paths that have led to discovery. Such reconstruction detracts in no way from the merit of the discovery itself; indeed, it increases appreciation of the ability of a widely ranging intellect to extract, from one or a number of disparate fields, those elements which in new combination have afforded the solution of a problem. There is indeed an important and even an extensive background to Ludwig's invention of the kymograph, dating to Christopher Wren and Robert Hooke, if not beyond, which has passed almost without notice in the history of physiology. We have ourselves called particular attention to the self-recording anemometer of Ons-en-Bray as a remarkable example of a group of early self-recording instruments (2). These in turn were progenitors of a growing number of recording instruments in meteorology, physics, and industry which were developed as the industrial revolution was achieved, and scientists began to study the nature and means of control of the new forces that had been released. It was at the height of this general development that the kymograph appeared as a special application of recording techniques to physiology. These events center almost entirely on the scientific world of Paris in the i840's, and especially upon the faculty and graduates of the lcole Polytechnique. The immediate stimulus seems to have come from the invention of the ballistic galvanometer by Claude Servais Pouillet, a former professor of physics at the ]tcole Polytechnique, a professor of physics at the Faculte des Sciences and Director of the National Conservatory of Arts and Crafts (3, 4). The ballistic galvanometer he invented had double merit; it made possible the accurate measurement of brief intervals of time, but more importantly, as far as the history of graphic recording is concerned, it initiated a chain reaction of publication in which the method of graphic recording in a variety of applications was brought into sharp focus before the scientific world.