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Norman Tuck © 1989

20 feet high x 8 feet wide x 5 feet deep

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

The Exploratorium Clock is a weight driven pendulum clock that utilizes a pendulum variation of a 13th century verge and foliot (crown wheel) escapement, the earliest known type of mechanical escapement. It was created by Norman Tuck as an Artist-in-Residence project at the Exploratorium Museum in San Francisco in 1989.


This clock uses a wooden pendulum with a bob created from a bowling ball. Wire baskets of weights, marbles or stones drive the clockwork mechanism. Every few minutes the falling drive weights contact a sealed mercury switch to trigger an electric motor to raise the weights using the principal of Huygens’ endless chain.


The hour hand’s 1:12 drive mechanism utilizes bicycle chains and sprockets. The time can be re-set using a lower crank linked to the face by a long steel rod.


The clock had been on exhibit at the Exploratorium’s Palace of Fine Arts location where it proved to be accurate and reliable until the Museum relocated in 2013.


The Exploratorium Clock was included in the 1991 Art From the Exploratorium traveling exhibition, traveling to: The World Financial Center, New York City; Canary Wharf, London; and The Israel National Museum of Science, Haifa.


From Wikipedia:

The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'. Verge escapements were used from the late 13th century until the mid 19th century in clocks and pocketwatches. The name verge comes from the Latin virga, meaning stick or rod.

Its invention is important in the history of technology, because it made possible the development of all-mechanical clocks. This caused a shift from measuring time by continuous processes, such as the flow of liquid in water clocks, to repetitive, oscillatory processes, such as the swing of pendulums, which had the potential to be more accurate. Oscillating timekeepers are used in all modern timepieces.

explo clock haifa 2.jpg

The Israel National Museum of Science

Haifa, 1991

Explo Clock _ World Fina001.jpg

The World Financial Center

New York City, 1991

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