The Falling Globe Clock at the Society of Antiquaries, London
This object consists of an engraved terrestrial globe with 24 hours marked by Roman numerals around the equator on a moving ring, connected with a brass strap to two other moving rings, one above and one below the tropics. The lower cap has an engraved clock dial indicating hours and minutes by means of hands, and is also engraved:
Presented to the Society of Antiquaries by B. L. Vulliamy AD. 1850.
The two train, weight-driven movement is set within the globe with its plates positioned horizontally at the lower end of the central cylinder. The going train is regulated by a verge and crown wheel escapement controlled by a sprung balance wheel. The striking train strikes the hours and halves on a bell mounted on the top plate and is controlled by a count wheel.
The clock is powered by its own weight by the following mechanism: A single chain is hooked and partially wound around the going train barrel, the chain then passes over a pulley attached to a rod suspended from an outer frame, before being wound around and hooking onto the striking train barrel at the other end. The result of this is that the entire clock and case are ‘hung’ from the pulley on the rod by the chain, their combined weight pulling down on the chain and causing the barrels to be rotated and the chain gradually unwound from each barrel. The clock is constructed with a stop intended to prevent the globe from descending far enough to unhook the chains from the barrels. The clock has duration of approximately two days and is ‘wound’ simply by lifting the globe back up the central rod, whereupon the chain is rewound around the barrels by means of two small spring barrels driving them with wheels.
The clock was originally manufactured in France c1690, and has undergone a series of modifications and losses throughout its existence. In 1850 it was presented by Benjamin Lewis Vulliamy to the Society of Antiquaries, where it has remained since. It is unknown where it was prior to this, or how it came to be in Vulliamy’s possession.
The provenance, age and unique design of this clock informed a conservation approach designed to intervene as minimally as possible in order to ensure the object is safe and stable as a static object on display, as well as being able to be run for a short amount of time on very rare occasions. Any future running of the clock is not intended to be accurate, but simply to demonstrate the mechanical function of the object.
The conservation work consisted mainly of careful, manual cleaning to remove corrosion, dust and congealed oil. Some removable components were added to address stability issues such as the loose hands and loose bell. Equally, 18 screws of various types were made to replace ones that had been either lost or replaced with poor-functioning modern screws. These screws were all made and finished by hand to match the aesthetic and design of the extant examples, and were stamped (where possible) to indicate that they are not original. The threads were cut using a combination of adjustable dies in order to match the existing threads in the holes, thereby preserving the original design and materiality of the object.
The complete disassembly of the clock for conservation work was also a rare opportunity to further study the object and aid in its future interpretation, so two extensive reports were prepared – one covering the history, function and conservation work, and another more detailed, examining each individual component and describing its condition, relationship to other components and signs of alteration or originality. Finally, an audio-visual recording of the clock functioning both in and out of the case was prepared so that its functionality is more readily visible to future viewers.
The conservation and documentation of the Globe Clock was undertaken as part of my final year practical work at West Dean College in 2019, and I continue to care for this, and the Society’s other clocks, in my role as their horological conservation consultant.
The clock re-installed in the library of the Society once conservation work was complete.
The reassembled movement after cleaning and conservation work.
The fine sculptural details of the screws, spring feet and gate-locking detents, showing the quality craftsmanship that went into the original manufacture of this clock.
FTIR Analysis carried out to identify corrosion products on the plates and ensure sufficient cleaning procedures were carried out.
Removable brass spacer to prevent rattle during striking due to the oversize bell mounting hole. The conservation-grade copolymer, Plastazote, was used to replace the severely degraded leather that had previously been used as a buffer pad between the bell, bell-nut and bell-stand.
The fly (pre-treatment) with ragged replacement of fly-spring with a piece of spring-steel which was found to be very brittle.
Multiple modern nuts and washers had been added to the motion-work to keep the loose-fitting hands in place, but were not functioning. Due to the unusual design of the motion-work mounting, a single, long cast-brass cylinder was used to replace the modern nuts and secure the hands.
A new fly spring was made from brass and secured with a friction-fit rather than riveting, in order not to interfere with historic material.
Replacement screws for the bottom case cap.
Replacement screws for securing the bottom case section to the central cylinder.
Replacement screws for securing the upper-middle case section to the central cylinder. The unusual design of these screws matches the extant ones that secure the lower-middle case section. All of the upper-middle section screws had been lost.