The history of 20th century particle physics has typically been periodized around the epochal breaks of theory: quantum discontinuity (1900), special relativity (1905), general relativity (1915), quantum mechanics (1926), quantum field theory (1948) and so on. Dr. Galison argues, both in his prior work supported by his Presidential Young Investigator Award, and in this project, that there are traditions of instrumentation with the same degree of complexity and partial autonomy that we usually ascribe only to high theory. Furthermore, these instrumental traditions carry with them characteristic forms of experimental demonstration and therefore play a primary role in the acceptance and rejection of new empirical phenomena. Dr. Galison is also investigating two interrelated features of instrumentation: 1) the split of particle physics detectors early in the 20th century into an instrument tradition that produces highly resolved "Golden Events" (e.g. the cloud chamber, the nuclear emulsion, the bubble chamber), and a competing instrument tradition that produces "high statistics" -- vast numbers of events with relatively little information contained about each event (e.g. the Geiger-Muller counter, the spark chamber, the wire chamber); 2) the profound division of research labor, beginning in the 1930's and accelerated in wartime weapon projects) that prevents one person from participating in all aspects of the experimental enterprise. Together the enormous expansion in scale and the tension between two traditions provide a framework in which to locate a history of particle detectors. Particle physics detectors are the site where experimental work in physics has undergone the greatest mutation. By tracing the history of this inner sanctum of the experimental physicist, one gains insight not only into the changing historical sense of the very term "experiment," one also sees in a different light the connections between physics and the wider technological culture in which it is situated.