"While philosophers and historians commonly speak of science in terms of theory and experiment, when they speak of the development of scientific knowledge, they speak in terms of theory alone." A decade ago, this observation was generally true. The analysis of experimentation and instrumentation is a relatively new trend in the history and philosophy of science. The post-positivistic philosophy of science tended to focus on the theoretical aspects and created a framework unfriendly to the contributions of experiment, instrumentation, and measurement to scientific knowledge.¹ Until very recently, both philosophers and historians of science paid very little attention to the "everyday activities' of scientists in the laboratory.