Maker, E. Dent, London, England. Model - Concorde, c. 1970's. 30"h x 14"w x 11"d. Serial number 006 of 35 made. Harrison style, grasshopper escapement with compound pendulum; 2 second cycle, Harrison spring style 20 second style remontoire, Huygens style endless chain 7 minute remontoire for winding.
View of endless rope train remontoire. Note fly fan air brake
View of escapement spring remontoire Grasshopper escapement
Note the similarity of this design with that of the Mathias Schwalbach tower clock remontoire.
Reworked daisy cam.
This was one of a series of skeleton clocks made by the Edward Dent company in the 1970's. Some were replicas of skeleton clocks made by famous makers in the prior century. Two examples of these Dents in my collection are the Rolling Ball clock by William Congreve, and the Epicyclical clock by William Strutt. In contrast, the clock illustrated below is a 2/3 sized version based upon a contemporary, original design by Martin Burgess of England, now in the collection of Donald Saff. He has written an informative article which appeared as the cover story in the Horological Journal, August 2001 about the restoration of the original clock. This Dent version was featured on the cover of Clocks Magazine, August 1973. and there is also an entry in British Skeleton Clocks, Derek Roberts, pp. 204-206 it also has drawings showing the grasshopper escapement.
About 25 of these were made in the 1970's. In 2000 to 2001, ten unassembled movements were discovered; assembled and finished. This example is from that later batch. Obviously the units were not sold in strict serial sequence. Total made - approximately 35. I know of 6 of the original production in existence. Sales were poor. The retail cost of these at that time was about $7000, quite a bit of money for a replica clock, and so it was quickly discontinued.
The clock has many unusual features. It has John Harrison's 'Grasshopper' escapement which is fascinating to watch and gets it's name from the way the escapement kicks away from the escape teeth like the leg of the insect. It also has two types of remontoire, also known as 'constant force escapement'. One is Harrison's escapement spring remontoire (also used by the Schwalbach tower clock) and the other an electrically driven version of Christiaan Huygen's endless rope train remontoire. A remontoire is not properly an escapement but a constant force device used to deliver an even and constant power to the escapement and simultaneously separate it from errors that may be produced further down the wheel train. These were used rarely, and only on expensive, high quality clocks. It was most useful in tower clocks. See the tower clock section for more in depth discussion of remontoire and their applications. For escapement remontoire as is used in this clock see Schwalbach tower clock. For train remontoire see Wagner, Paris.
When I purchased the clock, it had a mis-cut remontoire daisy cam causing the clock to stop. I re-cut part of the cam and it has been running without incident since. The design is highly stylistic and was made to maximize visual appeal. This is in keeping with Mr. Burgess designs in which his clocks are often called 'sculptural' in their appearance and function.
The spring remontoire detent advances the escape wheel every 20 seconds while the electrical remontoire rewinds the weights which power the clock every 10 minutes. The pendulum is compound, on a knife edge suspension and has a two second period which produces a slow, hypnotic movement.