An analysis of the optical revolution in the context of early 19th century Britain. Far from merely involving the replacement of one optical theory by another, the revolution also involved substantial changes in instruments and the practices that surrounded them. People's judgements about classification, explanation and evaluation were affected by the way they used such optical instruments as spectroscopes, telescopes, polarisers, photometers, gratings, prisms and apertures. There were two instrumental traditions in this historical period, each of which nurtured a body of practice that...