Updated: 28 Jan 2007

Gallery in course of arrangement

This gallery of the museum is dedicated to clocks with unusual motive power.

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CORNELIUS DREBBEL'S CLOCK

Cornelis Drebbel- the same man who is suppose to have rowed a boat underwater up the Thames- built a device in 1610 which was apparently a clock telling the time, date, and season. The gold machine was mounted in a globe on pillars and appears to have been powered by changes in air pressure. So far I have found no details of this.

COX'S BAROMETRIC CLOCK

In the 1760s the well-known clockmaker Mr James Cox developed a clock which was were wound up by changes in barometric pressure. The work was done in collaboration John Joseph Merlin, with whom Cox also worked on developing automata. Two large glass vessels containing no less than 68 kilograms (150 pounds) of mercury were connected together by an ingenious system of cords an pulleys so that the pulleys would rotate back and forth as the atmospheric pressure rose and fell. A sector-and-pinion mechanism converted this to unidirectional motion so that winding occurred on both rising and falling pressures. Cox claimed that his design was a true perpetual motion machine, which of course it was not.

Cox was a well-known clockmaker. He showed his self-winding clock in a private museum along with other fine clocks. When he died in 1788, a Mr Thomas Weeks bought the clock for his museum. It stayed in his museum until the 1830s, when it was sold, and disappeared from view until it turned up again on public display in 1898.

Cox's clock is currently in the Victoria & Albert Museum in London, and one of these days I mean to go and track it down. Remarkably, there is no image of it so far as I can tell.

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THERMO-PNEUMATIC CLOCKS
The images in this section were very kindly provided by John Howell.

Left: The back of a Puja clock made by the German firm of Jauch and Schmid. The notion here is to power a clock with mains electricity of uncertain voltage and frequency. It is perhaps significant that the patent for the principle (no. 714893) was granted in Germany in 1940. At the lower left, shielded by a translucent housing, is a carbon rod resistance that heats the coloured alcohol in the glass vessel just above it. This causes some of the alcohol to vapourise, the pressure pushing the liquid up the connecting pipe to the vessel at top right. As the latter gets heavier the wheel bearing the four vessels experiences a torque that rewinds a remontoire* spring driving a conventional gear train and escapement. This clock has a pendulum-controlled escapement, but models with balance wheel escapements also existed. The firm of Jauch and Schmid was registered in 1930

*A remontoire, from the French 'remonter' (to rewind) is a spring or gravity reserve of power that can be configured to give a near-constant driving torque because it is rewound at frequent intervals from another power source- usually this was a mainspring, whose own torque would slowly decrease as it unwound. The idea was that rewinding a spring or lifting a weight at relatively frequent intervals isolated the escapement from the variable torque of the mainspring.

Left: Advertising material for the Puja clock movement. This version has a balance-wheel escapement attached instead of a pendulum.

To save you the trouble of grappling with a German-English dictionary, here are the translations of the salient words in the advert above; "wechselström" means "alternating current", "gleichström" means "direct current", "thermo-aufzug mit glaskolben-laufrad" translates as "thermo-lifter with glass bulb impeller", and "gehwerk" as "movement".

Left: Another Puja clock movement.

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THE ATMOS CLOCK

Anyone interested in oddly-powered clocks will have heard of the Atmos clock, which is driven by changes in temperature. Find out more via these links:

http://www.compadapt.com/atmos.html

http://www.abbeyclock.com/lecoultre.html

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