Model: S02 Double Slider Trammel Ellipse Tracing Linkage
This is a classic trammel ellipse drawing mechanism with roots in the Renaissance. Two perpendicular slots permit two prismatic sliders with a connecting link to oscillate between vertical and horizontal positions though a turning crank in the back. It is well known that an extension of the connecting rod will trace an exact ellipse. One can also show that the midepoint of the connecting rod generates an exact circle. In this model, Reuleaux creates play in the vertical slot to show that with a driving crank attached to the midpoint of the connecting rod, the unguided end of the connecting rod will still generate a straight line. Further up the guide the gap is closed to show the workings of the classic trammel. Thus this model embodies two mechanisms.

A working model of this mechanism may also be found in the Deutsches Museum in Munich in the Mathematics section. The description attributes the invention to Benjamin Bramer (1588-1652) c. 1600, as well as to Frans von Schooten (1615-1660), Dutch, around the same period. However there is also credit for an ellipse drawing mechanism given to Leonardo da Vinci by Reuleaux (See Models D-10, D-12) This suggests that the idea of an ellipse drawing device may have been common knowledge among artists and mathematics in the Renaissance. There was great interest among artists in the use of geometry (e.g. perspective) in representing exactly real world objects and often the study of art and mathematics were closely linked.

Francis Moon 2003-07-01

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