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Date: 1962

Inventory Number: 1997-1-1649

Classification: Demonstration Model

Subject:

Maker: Walter Balcke ?

Cultural Region:

Place of Origin:

City of Use:

Dimensions:

2.5 x 18.3 x 14.3 cm (1 x 7 3/16 x 5 5/8 in.)

Material:

DescriptionThe apparatus is mounted on a circular black plexiglass base with a thick white plexiglass border. The top panel of the apparatus is a clear orange plexiglass disc. It is impossible to know what color the interior components are because this top disc makes everything inside appear orange, including the inner edge of the white plexiglass border. There are two interior components, each a flat, rounded teardrop shaped plexiglass piece. The two pieces are overlapping. Each interior piece has two lines etched onto its surface. The thicker line on each piece runs the long direction on the surface, the thinner line cuts across the thicker part of each base. Given the overlapping of the two components, the four lines together form many permutations of two intersecting angles.

The two interior components are attached to a wooden piece that slides along a wooden track fixed to the back of the apparatus (i.e. cut through the black base circle). Sliding the wooden piece back and forth in the track rotates the two interior pieces around in the apparatus changing the intersections of the lines. Painted in white on the surface of the apparatus is a conic section. No matter what position the two interior pieces are in, the two intersection points of the two angles fall on the edge of the conic section.

The two interior components are attached to a wooden piece that slides along a wooden track fixed to the back of the apparatus (i.e. cut through the black base circle). Sliding the wooden piece back and forth in the track rotates the two interior pieces around in the apparatus changing the intersections of the lines. Painted in white on the surface of the apparatus is a conic section. No matter what position the two interior pieces are in, the two intersection points of the two angles fall on the edge of the conic section.

Signedunsigned

FunctionWalter Balcke built and gifted many mathematical models to the Mathematics department at Harvard University. According to substantial correspondence between mathematics professors and Balcke, the models were sometimes used in classes, circulated around the department for observation, and eventually put on display in the mathematics library.

This particular model demonstrates the conic tracing intersection of two angles. The lines drawn on the two interior pieces form two angles which intersect variously given the movement of the wooden slider in the track. The apparatus is designed to demonstrate that the two intersection points between the two angles fall on the edge of the conic section: the angles change but the points of intersection are fixed.

This particular model demonstrates the conic tracing intersection of two angles. The lines drawn on the two interior pieces form two angles which intersect variously given the movement of the wooden slider in the track. The apparatus is designed to demonstrate that the two intersection points between the two angles fall on the edge of the conic section: the angles change but the points of intersection are fixed.

Curatorial RemarksIt is not verified that this object was constructed by Walter Balcke for the Mathematics Department at Harvard University. However, it is constructed in the same style and same materials as other confirmed Balcke models and is very likely one of them.

ProvenanceFrom the Department of Mathematics, Harvard University.

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