93rd Auction


Lot 540

Thomas Mercer Ltd., St. Albans, England, Movement No. 500, Height 1350 mm, circa 1925
Extemely rare astronomical tank precision regulator with detached spring impulse gravity escapement, electric wind and seconds contact device - English reproduction of a Riefler watch type D
Case: grey, air pressure constant steel tank with glass dome. Dial: regulator dial, 0-23 hour indicator, silvered. Movm.: gilt brass full plate movement mounted on massive aluminium block, adjustable knife edge suspension for pendulum on agate discs, Invar pendulum after Riefler's type J1 with small table for weights and fixed amplitude scale.
Until a few years ago only four clocks of this type were known; three of them are in museums in London and Washington – so the discovery of this clock that has been in private ownership in Germany for decades is certainly something of a sensation.
According to Tony Mercer (in "Mercer Chronometers", Ashford, 1978, p. 81), only a very small number of these clocks were ever produced (in cooperation with mit E. T. Cottington) and delivered to observatories such as those in Hong Kong, Tokyo and Buenos Aires.
Reproduction of Riefler precision pendulum clocks
The exceptional quality of the Riefler precision pendulum clocks and outstanding watchmaking skills saw to it that this type of clock was not only produced by the Clemens Riefler company, but also by British manufacturers such as the clock and chronometer factory Mercer in St. Albans. The English trade journal "The Watch and Clock Maker" reports on November 10, 1933 on the marvellous Riefler clocks and the reproduction built by Edward Cottingham. The article also mentions the Riefler pendulum and the escapement, stating that both are most useful and, what’s more, extremely pleasing for the eye.
Source: D. Riefler, "Riefler-Präzisionspendeluhren 1890-1965", Callwey, p. 138


37.00055.000 €
Price realized
37.200 €