In his 1860 paper On the theory of compound colours, James Clerk Maxwell described an instrument used to obtain a direct comparison between daylight and a mixture of three selected spectral colors. This investigation was part of Maxwell's study of human color vision, color perception, and color representation, and it encompasses his main achievements in the field. The working principle underlying this device provided the basis from which color diagrams have been derived, beginning with the standard chromaticity diagram proposed by the International Commission on Illumination in 1931. We describe a reconstruction of Maxwell's original version of the color box. Constructing and analyzing data obtained with such a replica could serve as a semester project for advanced optics students.

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See supplementary material at https://www.scitation.org/doi/suppl/10.1119/5.0087786 for more details on Maxwell's original method to detect wavelengths (S1) and Maxwell's color chart's determination (S2). Furthermore, see Secs. S3, S4, and S5 of the supplementary material for some insights about the choice of the components and geometrical construction of the replica, the determination of our scale in comparison with Maxwell's original one, and the realization of our color diagram, respectively. In Sec. S6, a list of the required components and approximate prices can be found.
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Supplementary Material

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