demonstration of Peaucellier-Lipkin straight line linkage
Date: 1959
Inventory Number: 1990-5-0030
Classification: Mathematical Model
Dimensions:1.7 x 20.8 x 13.3 cm (11/16 x 8 3/16 x 5 1/4 in.)
Accessories: in library folder (Lib 4927):
-twenty-one letters from Joseph L. Walsh, mathematics professor at Harvard University, to Walter Balcke, dated between 27 May 1957 and 24 January 1964 (letters thank Balcke for the many mathematical models he gifted to the Mathematics Department, praise his skill and ingenuity, many invite him to faculty and personal luncheons, and one letter provides an analytic solution to the "13-point problem" behind one of Balcke's models)
- one letter from J.L. Walsh pertains directly to this object, dated April 21, 1959
-three letters from Garret Birkhoff (then Chairman of the Harvard Mathematics Department) dated 3 March 1954, 4 January 1955, and 10 January 1955, each expressing gratitude (and in one case, an official department thank you) for the many mathematical models he gifted to the mathematics department
-photocopy of original envelope in which correspondence between mathematics department and Walter Balcke was stored (original was destroyed on 13 July 1997)
-photocopy of instructional card for object 1997-1-1671
- seven instructional cards that accompany the following Balcke models: Pascal's Theorem, Brianchon's Concurrent Lines, Trisector, Twelve Point Ellipse, Rolling Parabola, unknown, Equation Solution with a 'Constant' Variable and Thread
- photograph of the display case containing Balcke's models in the Harvard Mathematics department
DescriptionThe model is mounted in a rectangular mahogany frame. The frame is backed by a rectangular black plastic panel. A panel of plexiglass is mounted on the front of the frame. The model itself is constituted of partly transparent, white plastic parts. There is a track along the top edge of the model frame, with rounded edges and a thin slit cut the full length. A small red pin slides horizontally along the track. It is attached to a hole in a short arm with three other holes. Two holes have cross beams fitted in them that attach this arm to another, parallel and identical arm. One hole in each of these arms, that does not serve to attach them together, attaches to another arm that begins thin and becomes thicker towards the bottom of the model. Each of these arms ends with a half-circle hook fixed to a pivot near the bottom edge of the frame. The final, fourth hole of the second parallel straight arm is attached to a circular component with a second tier circle of slightly less diameter and with geared teeth.