J. Plateau: on the measurement of physical sensations and on the law which links the intensity of these sensations to the intensity of the source. J. Plateau: report on 'Psychophysical study: theoretical and experimental research on the measurement of sensations, particularly sensations of light and of fatigue' by Mr. Delboeuf. 1872.

Two papers published in 1872 by the Belgian physicist Plateau are here translated into English. The first paper contains the earliest published suggestion that the relation between physical stimulus magnitude and the strength of the internal sensation evoked is a power law and has been much cited for this reason. It also describes the earliest experiment to be performed, though not the first to be reported, on the subject of the psychophysical law. The performance of that experiment antedated Fechner's Elemente der Psychophysik by about 20 years. The second paper summarises a memoir in which a colleague, Delboeuf, reports his more extensive experiments on the subject and commends that memoir to the Belgian Royal Academy. In this second paper Plateau concludes that he was mistaken in supposing the psychophysical law to be a power relation.