“      Technicians are triply invisible. First, they have traditionally been invisible to historians and sociologists of science. . . . Second, they have been largely, if not entirely, invisible in the formal documentary record produced by scientific practitioners. Even when one is committed to doing so, it is extremely difficult to retrieve information about who they were and what they did. Third, technicians have arguably been invisible as relevant actors to those persons in control of the workplaces in which scientific knowledge is produced. . . . Technicians have been “not there” in roughly the same sense that servants were, and were supposed to be, “not there” with respect to the conversations of Victorian domestic employers.”