Model of a Spherical Representation of an Equipotential Surface by Richard P. Baker, Baker #427

This colorful model was made by Richard P. Baker in the early twentieth century when he was on the faculty in mathematics at the University of Iowa. It has a wooden base, painted black around the edges, with a painted grid showing polar coordinates atop this. Long bolts support three partitioned levels of painted metal circles above the base. Vertical rectangles join the circles.

A paper tag attached to the underside of the model indicates it is a model for Moebius's theorem, with Baker's model number 432d. On the other hand, a number etched into one of the edges of the base reads: 427.

According to Baker’s 1931 catalog, his model 427 is a model of the spherical representation of the equipotential surface represented by model 426 (an example of model 426 has museum number MA.211257.078). According the catalog, model 432d is of type his E, that is to say a wire and thread model with its projection shown a paper surface attached to a wooden base. This model is not of that type. Hence it seems likely that this is model 427, although no type for it is given in the catalog.

Reference:

Baker, R.P., Mathematical Models, Iowa City, 1931, p.1, 9, 13.

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