Peaucellier Dial

Martin says:

"As a mechanical design engineer I have always been interested in linkages to assist in solving motion problems. Even today many common artifacts rely upon linkage mechanisms, even aspects of robotics. In 1864  Charles-Nicholas Peaucellier announced that he had developed a linkage which produced a perfect straight line motion at its end point.

The idea of a Peaucellier sundial was the result of an article in the NASS journal, Compendium, June 2006, 13(2):16-23, by NASS President Fred Sawyer. Fred's research established that Peaucellier proposed that a sundial could be designed consisting of only straight lines. Fred then developed the equations necessary to realise such a sundial. Using the necessary equations I designed my Peaucellier sundial.

The sundial is made from Krion, an acrylic based material, 450mm x 250mm x 12.5mm thick. The sundial was designed by me and machined on my CNC machine. It is latitude specific. At the top it carries a schematic of Peaucelliers linkage, purely for decoration and to associate the sundial with Peaucellier and his great invention. The time on the sundial is read at the intersection of the gnomon rod's shadow and the date/time scales. "

You can see Fred Sawyer's explanation of how he uses the equations to create the dial in one of the BSS YouTube recordings of our regular Zoom meetings. The link is https://www.youtube.com/watch?v=_WAevemOEWU and his explanation starts at 1 hour 6 minutes.