Model of a Scroll of Order Eight by Richard P. Baker, Baker #85 (a Ruled Surface)

Description:

This string model was constructed by Richard P. Baker, possibly before 1905 when he joined the mathematics faculty at the University of Iowa. Baker believed that models were essential for the teaching of many parts of mathematics and physics, and over one hundred of his models are in the museum collections.

The typed part of a paper label on the bottom of the wooden base of this model reads: No. 85 (/) SCROLL OF ORDER 8 (/) CONES WITH COMMON VERTEX.

Baker’s string models represent a special type of geometric surface called a ruled surface. A ruled surface, sometimes called a scroll, is one that is swept out by a moving line. This model shows the ruled surfaces generated by the double tangents of two spheres through a line. The two spheres are white balls with diameters of three inches and 1 ½ inches (7.6 cm. and 3.8 cm.). The tangent lines are in blue thread – each thread is tangent to both spheres and passes through the line shown in yellow thread. According to Baker’s label and catalogs, the surface is of degree eight.

The model sold for $8.00.

References:

R. P. Baker, A List of Mathematical Models, [1905], p. 14.

R. P. Baker, Mathematical Models, Iowa City, Iowa, 1931, p. 8.

R. P. Baker Papers, University of Iowa, Iowa City, Iowa.