mathematical demonstration, angle divider (trisector ?)
Date: 1952-1964
Inventory Number: 1990-5-0028
Classification: Mathematical Model
Dimensions:case: 14.1 × 32 × 2.5 cm (5 9/16 × 12 5/8 × 1 in.)
Accessories: mahogany case; two circular protractors; clear plexiglass rule with serated edge
DescriptionThe demonstration set is mounted on a rectangular plexiglass base that is in turn mounted on a rectangular mahogany base. A mahogany lid fits onto the base, forming a case for the set.
Two concentric white plexiglass circles are fixed in the center of the base. Two spokes (or arms) emerge from each disc, pointing in the general direction of the four corners of the base. The discs can rotate, causing the spokes to slide back and forth across the plexiglass base, changing the angle between the spokes on each side of the apparatus.
Each of the spokes has a straight track (or groove) cut along its center. A blue, trapezoidal shaped plexiglass "slide" accompanies the set. It has three brown posts attached to three of its corners. These brown posts are the appropriate size to fit in the tracks of the spokes. A straight white line is etched along the long edge of the slide, between two of the brown posts. In between two of the spokes on one side of the apparatus is a raised plexiglass edge. The blue slide has a groove cut in its bottom panel that fits onto this track. The track can be used to limit the slide's degrees of freedom when the apparatus is in use.
The set also includes seven rectangular blue plexiglass strips with rounded edges. These act as "links" in the set. Three of these links have a brown post at each end. These posts are the appropriate size to fit in tracks on the spokes. The other four blue links have small holes at each end. These holes fit onto the top part of the posts. The blue slide, and the blue links fit together by holes and poles to create a linkage on the surface of the apparatus.
The set also includes two circular clear plastic protractors. Each one is divided into 360° by blue lines around the circumference. Every tenth degree is labeled with the appropriate numeral. Each protractor is further marked with the compass directions. N(orth) lines up with 0°, E(ast) lines up with 90°, S(outh) lines up with 180°, and W(est) lines up with 270°. A clear plastic attachment has been added to the 0° point on each protractor. Each attachment has a small rounded groove cut in its outmost edge. The attachments would have been used to attach the protractors to the set. It is no longer clear where and to what they would have been attached.
The set is also accompanied by a clear plexiglass bar with one serrated edge, whose use is unknown.