THE PUBLIC CLOCK

The Public Clock.

Norman Tuck ©1989

 

20 feet high x 8 feet wide x 5 feet deep

 

The Public Clock is currently in the collection of the Artist.

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Public Clock…While the quality of playfulness is without a doubt present, it no way sabotages the sophistication of this body of work. A fluent knowledge of physics is essential to work such as Public Clock, a tall gravity-powered clock made from bicycle parts and oddly-matched weights…. “   Margaret Shearin, Triad Style, Nov. 13, 1991, Page 10

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Public Clock … substitutes a wire basket full of marbles for the lead weight. The gradual lowering of the basket powers not only a large pendulum, but also the knifelike metal hands on a clock face at the top of this structure that resemble an outdoor windmill. An electrically powered rewind device automatically raises the basket of marbles when it reaches the bottom of its path.”

                                Tom Patterson, Winston-Salem Journal, Sunday, January 19, 1992 Page C3

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The Public Clock utilizes a weight-driven five-legged gravity escapement similar to the one used on Big Ben.  A bowling ball hangs from a wooden pendulum to regulate the clock, and a falling basket of stones or marbles drives the clock. 

 

Every few minutes the falling drive weights contact a sealed mercury switch to trigger an electric motor that raises the weights using the principal of Huygens’ endless chain.

 

The giant “wheels” on this clock are made from links of industrial roller chain (bicycle style chain) welded together to form giant “lantern gears” that mesh with toothed bicycle sprockets. The hour hand’s 1:12 drive and a lower “setting” mechanism utilize standard bicycle components.

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Versions of The Public Clock have been exhibited at: The Southeastern Center for Contemporary Art, Winston-Salem, NC, 1991; City Gallery of Contemporary Art, Raleigh, NC, 1992; Technorama Museum, Winterthur, Switzerland, 1993; The Exploratorium, San Francisco, CA, 1994; Liberty Science Center, Jersey City, NJ, 1996; Inventure Place, Akron, OH, 1996;  The Science Museum of Minnesota, St. Paul, MN, 1999; and The Israel National Museum of Science, Haifa, 1991.

 

From Wikipedia:

A gravity escapement uses a small weight or a weak spring to give an impulse directly to the pendulum….

The design was developed steadily from the middle of the 18th century to the middle of the 19th century. It eventually became the escapement of choice for turret clocks, because their wheel trains are subjected to large variations in drive force caused by the large exterior hands, with their varying wind, snow, and ice loads. Since in a gravity escapement the drive force from the wheel train does not itself impel the pendulum but merely resets the weights that provide the impulse, the escapement is not affected by variations in drive force.

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