Abstract: Investigating the connection between instrumentation and measurement, this chapter focuses on the microscope, which is perhaps the best example of an instrument used in measurement, and putatively as a means to extend the reach of the senses. In fact, the relation between observation, experiment, and measurement is far from simple. Measurements occur in general only as special elements of the experimental procedure by which objects are deliberately placed in unusual, artificially designed conditions — conditions in which they are made to respond to the questions put to them. Under these conditions, measurement procedures produce representations — images — with complex, theory-mediated relations to the entities on which the measurements are made. In distinguishing the various roles of instrumentation in experiment we automatically induce a corollary taxonomy of experiments, distinguishing for example mimetic experimentation from the creation of new phenomena, providing thus also a precise setting for assessment of empiricist views of science.

Keywords: instrument, image, measurement, experiment, microscope, Hooke, rainbow, reflection, Heidelberger,