This book explores a little-studied arena that exists between science and technology, an arena in which a singular and important variety of open-ended, multi-purpose instrumentation is developed by practitioners (neither scientist nor engineer, call them research-technologists) for use in academia, industry, state metrology and technical services, and considerably beyond. The generic instrumentation designed in this almost subterraneously institutionalized/professionalized, interstitial arena fuels both science and engineering work. This involves intermittent crossings of the boundaries that demarcate and protect the conventional cognitive and artefact cultures familiar to many historians and sociologists. Research-technologists thereby comprise a distinctive (but never distinct) transverse science and technology culture that generates a species of pragmatic universality, which in turn provides multiple and diversified audiences with a common repertory of vocabularies, notational systems, images, and perhaps even paradigms. Research-technology practitioners deliver a lingua franca that contributes to cognitive, material, and social cohesion. Research-technology is about the complementarity between boundary-crossing and the stability/maintenance of boundaries.