The Rolling Ball Web
An Online Compendium of Rolling Ball Sculptures, Clocks, Etc.
By David M. MacMillan et. al.
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A "Congreve" Style Rolling Ball Clock
Photo by and Copyright © 1997 Ray Bates, MBHI
(4 images, approximately 116 kilobytes total)
Portrait of Sir William Congreve by James Lonsdale. This image is in the public domain. It appeared in the U. S. Government publication "Sir William Congreve and His Compound-Plate Printing" by Elizabeth M. Harris. United States National Museum Bulletin Number 252, pages 70-87, "Contributions from the Museum of History and Technology: Paper 71. Washington, D.C., Smithsonian Institution Press, 1967, printed by the U.S. Government Printing Office and offered for sale by the Superintendent of Documents, U.S. Government Printing Office.
In the early 19th century, Sir William Congreve invented a new type of rolling ball clock, apparently without knowledge of previous activities in the field of rolling ball clocks.
Congreve's clock differs from earlier designs in its mode of operation. Instead of rolling a ball down a fixed incline, Congreve's clock rolls a ball in a zigzag path across a tilted table. When the ball reaches the lower side of the table, the table tilts, raising the low side. The ball rolls back, and the cycle continues.
Congreve's clock is particularly interesting from the point of view of the history of the development of precision clocks because it represents a very early conscious attempt at a clock whose oscillator is as free as possible from the influence of the escapement. Indeed, Congreve's 1808 patent covers the entire concept of what he termed an "extremely detached escapement." This concept was later to be very successful in electromechanical precision pendulum clocks of the 19th and early 20th centuries (e.g., the Hipp "butterfly" toggle mechanism and the Synchronome).
The oscillator in a Congreve clock is the combination of the rolling ball and the tilting table. Congreve's 1808 patent conceived of a table with a period (half cycle) of one minute. He believed that this oscillator was equivalent to a pendulum with a one minute period; such a pendulum, he calculated, would be 11,783 feet 4.800 inches in length. The difficulty with this analysis is that the virtue of a pendulum is that it is not just an oscillator but a resonator - it is an oscillator with a natural (or "resonant") frequency. The tilting table of a Congreve is just an oscillator, not a resonator.
As a minor point, it should be noted that Frank Hope-Jones' classic book Electrical Timekeeping contains an error in its brief discussion of Congreve clocks. Hope-Jones mentions the Congreve in the context of his discussion of Edwin Craig's rolling ball impulsing mechanism for free pendulum clocks. Hope-Jones says:
Why not use ... a rolling ball? [as the slave clock of a free pendulum clock system] Most of my readers will be acquainted with the rolling-ball clock of Sir William Congreve, which he made in 1808 for the then Prince of Wales. It was invented by Nicolas Grollier (1593-1686). It has served as a window attraction in jewellers' shops. A table-top is pivoted at its centre and has a shallow groove cut in its surface, zigzagging from side to side from one end to the other. Tilt it on its hinge and start the steel ball at the top of the incline. It will then have a long run, perhaps for half a minute; when it reaches the bottom it will strike a catch releasing a power train which will reverse the tilt, and the ball will return again along the same path. (210)
Hope-Jones' technical description is accurate, but his attribution to Nicolas Grollier (aka Grollier de Sevière;) is incorrect. Grollier described rolling ball clocks with fixed ball paths, not the tilting ball path of Congreve's clock.
The 11th Edition of the Encyclopædia Britannica, 1911, contains the following biographical entry on Congreve:
"CONGREVE, SIR WILLIAM, Bart. (1772-1828), British artillerist and inventor, was born on the 20th of May 1772, being the eldest son of Lieutenant-General Sir William Congreve (d. 1814), comptroller of the Royal Laboratory at Woolwich, who was made a baronet in 1812. He was educated at Singlewell school, Kent, and (1788-1793) at Trinity College, Cambridge, taking the degrees of B.A. in 1793 and M.A. in 1795. In the latter year he entered the Middle Temple, and up to 1808 he lived in Garden Court, at first studying law, later editing a political newspaper, and in the end devoting himself to the development of the war rocket, for which he is chiefly remembered. Through his father he enjoyed many opportunities of experimenting with artillery material, and finally in 1805 he was able to demonstrate to the prince regent, Pitt and others the uses of the new weapon. In 1805 he accompanied Sir Sidney Smith in a naval attack on the French flotilla at Boulogne, but the weather prevented the use of rockets. In another attack on Boulogne in 1806, however, the Congreve rockets, which were fired in salvos from boats of special construction, were very effectual, and in 1807, 1808 and 1809 they were employed with excellent results on land and afloat at the siege of Copenhagen, in Lord Gambier's fight in the Basque Roads and in the Walcheren expedition. Congreve himself was present in all these affairs. In 1810 or 1811 he became equerry to the prince regent, with whom he was a great favorite, and in 1811 he was elected a fellow of the Royal Society; in the same year he at last received military rank, being gazetted lieutenant-colonel in the Hanoverian artillery. In 1812 he became member of parliament for Gatton. In 1813, at the request of the admiralty, he designed a new gun for the armament of frigates, which was adopted and very favourably reported on. In the same year the newly formed "Rocket Troop" of the Royal Artillery was sent to serve with the Allies in Germany, and this troop rendered excellent service at the battle of Leipzig, where its commander Captain Bogue was killed. In recognition of their services Congreve was shortly afterwards decorated by the sovereigns of Russia and Sweden. Many years later the Congreve rocket was superseded by Hale's, which had no stick.
"In 1814, on the death of his father, Colonel Congreve succeeded to the baronetcy and also to the office of comptroller of the Royal Laboratory. He also became inspector of military machines, but his Hanoverian commission did not (it seems) entitle him to command troops of the ROyal Artillery, and there was a certain amount of friction and jealousy between Congreve and the Royal Artillery officers. During the visit of the allied sovereigns to London in this year, Congreve arranged the fêtes and especially the pyrotechnic displays which the prince regent gave in their honor. In 1817 he became senior equerry to the prince and a K.H., and in 1812 major-general à la suite of the Hanoverian army. In 1820 Sir William Congreve was elected M.P. for Plymouth (for which constituency he sat until his death), and in the following year, at the coronation of George IV. (whose senior equerry he remained), he arranged a great pyrotechnic display in Hyde Park. In his later years Congreve took a prominent part in various industrial ventures, such as gas companies, which, however, were for the most part unsuccessful. He died in Toulouse on the 16th of May 1828.
"Congreve was an ingenious and versatile man of science. Besides the war rocket he invented a gun-recoil mounting, a time-fuze, a parachute attachment to the rocket, a hydro-pneumatic canal lock and sluice (1813), a perpetual motion machine (see PERPETUAL MOTION), a process of colour printing (1821) which was widely used in Germany, a new form of steam-engine, and a method of consuming smoke (which was applied at the Royal Laboratory); he also took out patents for a clock in which time was measured by a ball rolling on an inclined plane; for protecting buildings against fire; inlaying and combining metals; unforgeable bank-note paper; a method of killing whales by means of rockets; improvements in the manufacture of gunpowder; stereotype plates; fireworks; gas meters, &c. This first friction matches made in England (1827) were named after him by their inventor, John Walker. He published a number of works, including three treatises on The Congreve Rocket System (1807, 1817, and 1821; the last was translated into German, Weimar, 1829); An Elementary Treatise on the Mounting of Naval Ordnance (1812); A Description of the Hydropneumatical Lock (1815); A New Principle of Steam-Engine (1819); Resumption of Cash Payments (1819); Systems of Currency (1819), &c.
"See Colonel J. R. J. Jocelyn in Journal of the Royal Artillery, vol. 32, No. 11, and sources therein referred to. The account in the Dictionary of National Biography is very inaccurate."
[This material from the 1911 Encyclopædia Britannica is in the public domain in the US.]
I have placed a
transcription, with illustrations,
of Congreve's 1808 patent online.
Thanks are due to the UK Patent Office for providing a copy of this
Without meaning any disrespect to the memory of Congreve, it may
be observed that there are many questionable points of physics
in Congreve's patent (even given the knowledge of physics of his time),
and that his prose is astonishingly bad.
It is nonetheless an important and interesting document.
Of course, this is all a matter of opinion.
Dana J. Blackwell, in reviewing the Turner and Devereux reprint of
Congreve's patent (see below)
says "The literary style of the paper is interesting as it exhibits
the self-confidence of the early nineteenth-century inventor."
(7 images, approximately 214.7 kilobytes total.)
Congreve's patent was reprinted, with introductory material by (I presume) A. J. Turner, in
Turner and Devereux. "William Congreve and his Clock," [Turner and Devereux] Occasional Paper No. 2. London, Turner and Devereux, 1972.
This Turner and Devereux publication is reviewed by Dana J. Blackwell in the Bulletin of the National Association of Watch and Clock Collectors, Vol. XV, No. 11, Whole No. 165 (August 1973), pages 1342-3.
Although Dr. Hans von Bertele's paper "The Rolling Ball Time Standard" deals primarily with 17th century rolling ball clocks, it opens with a nicely illustrated treatment of Congreve's 1808 clock. This clock, presented by Congreve to the Prince Regent of the UK, resides at the Rotunda of the Royal Laboratory at Woolwich. von Bertele's treatment includes three black and white photographs of this clock with identifications of some of the components. He also transcribes the identifying plate on this clock:
This first Experiment of a new Principle for THE MEASUREMENT OF TIME, invented by William Congeve Esq. is humbly presented to HIS ROYAL HIGHNESS THE PRINCE OF WALES.
Grovell & Tolkin fecit.
Roberts, in British Skeleton Clocks (79-82), devotes a section to Congreve. He gives some brief biographical information. Congreve was born in 1772. His father was a baronet and Comptroller of the Royal laboratory at Greenwich. Congreve joined his father there in 1791; he succeeded to both his father's title and position as Comptroller in 1814. (This is probably an error. The Encyclopædia Britannica, Lloyd, and Smith claim that it was Woolwich.) He developed the "Congreve Rocket." Roberts cites their use in "the latter part" of the Napoleonic wars (on land and at sea), at the Siege of Copenhagen (1807), and, under the command of Congreve, at the battle of Leipzig (1812). He was at one point a member of Parliament and became a Fellow of the Royal Society. He died in 1828.
[Question: The US National Anthem was written during the War of 1812 and refers to "the rocket's red glare." Were these Congreve Rockets?]
Roberts also cites some degree of controversy over Congreve's first clock. A clock exists (Roberts, p. ?, figure 3/1 - this figure is missing in my copy) from 1808 which was given to the Prince of Wales. There exists also a clock by Bryson (Edinburgh) apparently dated 1803 (Roberts cites Drake, T.A.S., "Congreve Clocks," Antiquarian Horology. 1.11 (1956)) which claims to be a copy of Congreve's. Roberts' thesis, in the absence of a physical examination of this clock, is that it, too, dates from 1808 (and that an '8' has been read as a '3' on its plaque). This first clock was, according to Roberts, constructed for Congreve by Gravel and Tolkein [sic]. It is weight-driven and at the time he wrote (1987) resident in the Rotunda at Greenwich. (This contradicts Lloyd, who claims it to be at the Rotunda at Woolwich.)
Roberts illustrates three more Congreve clocks, all of which are very similar to each other. One was made by John Moxon in the "early 19th century" (p. 80, figure 3/2). It is spring driven and features a seconds display It has a period of thirty seconds. The next, made by Andrew Barrie, is presumed to have been made shortly after Congreve's death in 1828 (p. 80, figure 3/3). It has a period of fifteen seconds. The third, anonymous but in the style of Moxon, has a thirty second period (p. 81, figure 3/4).
Roberts also cites in passing an example made by Dent's (UK) which was displayed in their Pall Mall shop window "until the late 1960s" (82).
Lloyd discusses and illustrates Congreve's original clock (pp. 114-115, plates 141 and 142). This clock was weight-driven (employing a cannon-ball as the weight). It has the same general layout as later traditional Congreve clocks, an open four-post arrangement with the tilting table within and multiple dials above, but it lacks the "pediment" of later clocks.
Lloyd has an entry on Congreve, in which he claims that Congreve's position was that of Comptroller of Woolwich Laboratory. I don't know my English history well enough to know whether or not this contradicts Roberts (who says Comptroller of the Greenwich Laboratory). Given that Woolwich was/had an arsenal (didn't it?) and that Congreve developed rockets, this would seem more likely.
Lloyd illustrates Congreve's 1808 weight-driven clock, which employs a spherical weight (p. 60, figure 144 - location given as the Rotunda at Woolwich, picture credited to the Officer's Mess, Royal Artillery, Woolwich) and a later spring-driven clock of unstated origin which is similar, but not identical, to those illustrated in Roberts (p. 60, figure 145).
Smith also has a Congreve entry. He places the original 1808 clock at the Woolwich Arsenal. He illustrates a different clock, which seems to be the same one that Lloyd illustrates in his figure 145 from a different angle (p. 35, figure 7). The location of this clock is given as the British Museum, London and its date is given as the 19th century.
The entry on Congreve in Smith was written by the notable horological historian Charles K. Aked ("CKA").
The Museum of the National Association of Watch and Clock Collectors (NAWCC) in Columbia, Pennsylvania, posesses at least one Congreve rolling ball clock. The example, NAWCC accession number 94.38, illustrated on their WWW pages, was built in 1885 by John Evans of London.
This clock was also featured, in color, on the back cover of the Bulletin of the National Association of Watch and Clock Collectors, Vol. 39, No. 6, Whole No. 311.
The NAWCC Museum may be reached on the WWW at: http://www.nawcc.org/
Thanks to Fortunat F. Mueller-Maerki, webmaster of Horology - The Index for bringing this clock to my attention.
Silvio Bedini illustrates a "non-temple" configuration Congreve in "Perpetuum Mobile" (86). He cites this clock as being in the "Museum of Horological Antiquities" in Columbia, PA. This would be the present Museum of the National Association of Watch and Clock Collectors, Inc.
This same clock is illustrated in the "Chapter Activities" section of the NAWCC Bulletin Vol XVII, No. 5, Whole No. 178 (October 1975): 522, under the activities of Chapter 7, the Headquarters Chapter. No futher information is given about this clock.
The remarkable English model engineer Dr. J. Bradbury Winter constructed an electrical "Congreve" clock. This clock was "just finished" when it was illustrated in the July 6, 1922 issue of The Model Engineer and Electrician (Winter, Dr. J. Bradbury. "An Unorthodox Workshop." Vol. XLVII, No. 1106, pages 6-7). A explanatory article with many drawings followed in 1923 (Winter, Dr. J. Bradbury. "Details of my Electric Congreve Clock." The Model Engineer and Electrician. Vol. XLIX, No. 1160 (July 19, 1923): 59-68.) Dr. Winter refers, in his construction article of 1946, to an appearance by this clock in the pages of The Model Engineer in the October 18, 1945 issue, but I have not yet checked this.
A full construction article appeared in 1946 (Winter, Dr. J. Bradbury. "A Congreve Clock: Details, Dimensions and Instructions for Making an Attractive Timepiece." The Model Engineer. This article was serialized in the following issues:
Vol. 94, No. 2330 (Thursday, Jan. 3, 1946): 4-7.
Vol. 94, No. 2332 (Thursday, Jan. 17, 1946): 64-67.
Vol. 94, No. 2334 (Thursday, Jan. 31, 1946): 124-127.
Vol. 94, No. 2336 (Thursday, Feb. 14, 1946): 178-181.
Vol. 94, No. 2338 (Thursday, Feb. 28, 1946): 223-226.
Vol. 94, No. 2340 (Thursday, Mar. 14, 1946): 274-277.
Vol. 94, No. 2342 (Thursday, Mar. 28, 1946): 310-313.
Vol. 94, No. 2344 (Thursday, Apr. 11, 1946): 370-372.
Vol. 94, No. 2346 (Thursday, Apr. 25, 1946): 420-422, 424.
Vol. 94, No. 2348 (Thursday, May 9, 1946): 465-457, 470.
Vol. 94, No. 2350 (Thursday, May 23, 1946): 513-514.
This series was reprinted in 1972, in issues:
Vol. 138, No. 3442 (2-15 Jun. 1972): 537-539, 552.
Vol. 138, No. 3443 (16-30 Jun. 1972): 601-604, 617.
Vol. 138, No. 3444 (7-20 Jul. 1972): 656-659.
Vol. 138, No. 3445 ?.
Vol. 138, No. 3446 (4-17 Aug. 1972): 741-744, 746.
Vol. 138, No. 3447 ?.
Vol. 138, No. 3448 ?.
Vol. 138, No. 3449 ?.
Vol. 128, No. 3450 (6-19 Oct. 1972): 948-951.
Vol. 138, No. 3451 (20-31 Oct. 1972): 996-999.
Vol. 138, No. 3452 (3-16 Nov. 1972): 1048-1050.
Dr. Winter departed from traditional Congreve clock practice in several interesting ways in his clock. Costmetically, this clock does not employ the "temple" style with dials on the "pediment" that characterizes most Congreves. Instead, it resides in a freestanding case with slightly gothic trim. The tilting table is under glass at the top of this case.
Wishing an accurate timekeeper, but recognizing the limits of the Congreve principle, Winter chose to make his Congreve the "slave" of a more accurate timekeeper. The dial of the clock is electrically driven from the Congreve mechanism. There is, additionally, a small carriage clock hidden in the case. Every half hour the electrically driven dial is synchronized to this more accurate timebase.
Dr. Winter also wished to produce, as much as possible, the illusion of perpetual motion. As he says in his 1923 article, "I have aimed in my design at hiding the means by which the inclined plane is rocked backwards and forwards; there is no visible connection between this and the hands although they obviously move simultaneously." To this end, the signal that the ball has reached the end of its travel and that the table should rock back is made electrically. Further, the electric wires are run through holes hidden in the mechanism.
Dr. Winter also employs an unusual mechanism to reverse the ball's direction of travel. Instead of simply coming to the end of its path, the ball strikes a line of three balls which sit at the end of its path. This causes it to stop, while its momentum is carried through the next two balls and transmitted finally to the third. This third ball rolls up a short incline, rolls back, and strikes the stationary balls, transmitting its momentum back to them. The "middle" two balls transmit this back to the "main" ball, which, the table having been reversed during this procedure, proceeds back along its course.
Dr. Winter notes in his 1946 construction article that on Mr. Stephens had constructed a copy of this clock using the information provided in the 1945 Model Engineer article.
The 1922 article by Dr. Winter is out of copyright and in the public domain, in the US at least. It is an interesting article which covers a number of the creations of Dr. Winter and describes the setup of his Swiss chalet workshop, complete with comfortable chairs, a piano, an overhead lineshaft drive, a planer, and a lathe. The section from this article concerning the Congreve is as follows:
Apart from the tools and appliances for the workshop, my biggest job up to the present has been the making of a clock on the Congreve principle. This is just finished and works well, but its chief merit lies in the extraordinary fascination of watching its movement. The method was invented by William Congreve one hundred years ago, and the only specimen I have seen is in the window of Frodsham's shop at 27, South Molton Street, London, W.
Instead of a pendulum to regulate the speed of the train of wheels, a ball runs along a series of grooves cut in the form of zig-zags across an inclined plane. When the ball reaches the end of its journey, the inclination of the plane is reversed and the ball travels back its zig-zag course (see Figs. 11 and 12).
In the original, the ball strikes a light lever at the end of each journey, which unlocks the train and reverses the inclination, but I have made a modification and have tried to hide the means by which this reversal is effected. In my clock all that can be seen is the plate pivoted in a pair of ordinary plummer blocks bolted on to a bedplate of oak.
Fig. 11. - The Grooved Plate of my "Gongreve" [sic] Clock,
showing the Travelling Ball and the two Sets of three Terminal Balls.
[image public domain]
I found that there was a little uncertainty and hesitation at the end of each journey when the ball had to make a fresh start, the incline being very slight, about 1 in 450. I have overcome this by placing a row of three balls touching [Page 7 begins] each other at the two termini (see Fig. 11). When the travelling ball hits the first of the three stationary ones, it stops dead, but the last ball in the train takes up the movement and runs for an inch or so till an up gradient checks it and sends it back. On striking the stationary balls its percussion is transmitted to the original travelling ball which starts off, promptly and at almost the same speed as when it arrived, very little force having been lost in friction. The whole operation only occupies a small fraction of a second, and just synchronises with the time taken by the plate to reverse its inclination, so that the travelling ball re-starts at the precise moment that the plate is suitably tilted.
The making of the oscillating plate with its grooves was a difficult and rather long business. It is made of steel, about 9 ins. by 8 ins., with eight grooves. I was working on this plate for over 400 hours. The rest of the mechanism is comparatively simple though there is plenty of it.
Fig. 12. - The Concealed Movement of my "Congreve" Clock
which causes the Grooved Plate to Rock."
[image public domain]
W. Daniel Hillis of The Long Now Foundation has designed an innovative Congreve-style clock which employs cycloidal tracks. More information, and illustrations of this clock may be found on a page devoted to Hillis' rolling ball clock.
John Wilding has written a book on the construction of a traditional Congreve, The Construction of a Congreve Rolling Ball Clock. It is 78 pages. My copy was produced by the author (or authorized by the author) using photocopy technology and is "comb bound." This book is available in the US from W. R. ("Bill") Smith, WRSmith2@aol.com.
Wilding's clock is unusual among Congreves in that it features a "skeletonized" table in which the ball path pierces completely through the table (in fact the table is build up from triangular pieces; this may be contrasted, for example, with Dr. J. Bradbury Winter's Congreve, where the table was manufactured from the solid using a planer). Wilding notes that this skeletonized table is not original to his clock; it appears in an unidentified Congreve clock in the collction (at that time, at least) of Albert L. Odmark, Seattle, USA.
The clock it describes was constructed by Wilding using his 3 1/2 inch (radius of swing) Myford ML7 lathe. In the US, where swing is measured by diameter rather than radius, this would correspond to a 7 inch swing lathe.
Wilding's book was reviewed by Henry B. Fried in the Bulletin of the National Association of Watch and Clock Collectors (NAWCC), Vol. XIX, No. 3, Whole No. 188 (June 1977): 297-198. This review includes a photograph of Wilding's Congreve (the same photo which appears on the cover of the book). It gives the original publication data for the book: Published by Brant Wright Associates, Ltd. 7" x 9 1/2", dust jacket with hard covers, 76 pages, 140 figures, [original price] $23.75."
A. H. Nettleton of the UK exhibited a Congreve clock of his own design and construction at "The Model Engineer Exhibition" in 1946, for which he received the silver medal. He describes this clock, with diagrams and a photo, in the August 21, 1947 issue of The Model Engineer, pp. 205-209. Despite the obvious high standard of construction, Nettleton says of this clock that "its time-keeping qualities are rather erratic" and that "no amount of adjustment will keep it consistent." He experienced errors of up to five minutes a day, apparently randomly.
Thanks to Bob Holmstrom for bringing this article to my attention.
Nettleton is named in the Acknowledgements for John Wilding's book The Construction of a Congreve Rolling Ball Clock.
Nevil Shute's (Nevil Shute Norway's) last novel, Trustee from the Toolroom (1960) features a Congreve clock. In the novel, the protagonist, Keith Stewart, has published a set of plans for building a Congreve clock. Two of the novel's characters in the United States are in the process of building this clock. According to R. L. East, "Storyteller from the Toolroom." Model Engineer. Vol. 129, Whole No. 3238 (1 December, 1963): 539-540, Shute took care to ensure that his description of the Congreve was accurate, and referred to (unspecified) Congreve publications in The Model Engineer while writing Trustee.
Devon Clock Kits (aka Devon Clocks Limited) in the UK sells a traditional Congreve clock in kit form. This kit is available in three levels of finish: "Basic" (requiring hand finishing, such as filing, sandpapering, and polishing), "Prepared" (requiring assembly and testing), and "Complete (assembled and tested). This is their Kit No. 3. It is 8.5" high, 6" deep, and 9" wide, and seems to run on a 12 second half-cycle. In 1996, according to their literature, this kit cost UKP 445 for the Basic version, UKP 545 for the Prepared version, and UKP 695 Complete.
Devon Clocks Limited Albion Works Albion Hill Exmouth Devon EX8 1JS UK Tel: (0395) 263943
Keith Anderson has graciously provided this illustration of a Round-Tabled Congreve by Charles Ruddick.
Sinclair-Harding in the UK have introduced the unusual congreve-style clock pictured below:
Sinclair-Harding Congreve Style Clock
Sinclair-Harding describe this clock as follows:
Based on William Congreve's principle, the Sinclair Harding Congreve clock uniquely has the track mounted on the top of the clock. The elliptical dial and track are made in Aluminum and Anodised in either Titanium or a dramatic Corinthian blue. Other options of colour can be incorporated upon request. The base is a piece of Derbyshire fossil, quarried only Once a Week, quarried on the Duke of Devonshire's Chatsworth estate and mounted on adjustable feet for easy levelling. Visible are the Fossils in the stone. The Fusee movement is controlled by the Ruby ball which after gently rolling down the track triggers the mechanism to index every 15 seconds. The whole movement is dust protected by a framed bevelled glass shade. An ccess hole is provided through the back of the glass to enable winding each week without removing the protective shade.
Width 37 cm. Depth 20 cm. Height 20 cm.
Another photograph of this clock, together with Mr. Robert Bray of Sinclair-Harding, appears in the August, 1998 issue of the British Horological Association's journal, Horological Journal.
Sinclair-Harding may be reached online at:
Robert Bray of Sinclair-Harding has indicated that "Comitti of London (ex Heritage International)" sells one and three dial Congreves. (1998)
A Congreve clock by Max Lembeck, member of the National Association of Watch and Clock Collectors (NAWCC) Chapter 60, Florida Gold Coast, is illustrated in the Bulletin of the NAWCC, Vol. XXI, No. 3, Whole No. 200 (June 1979): 372.
A traditional "temple style" Congreve was displayed at the 1997 North American Model Engineering Society (NAMES) Exposition in Wyandotte, MI by a member of the New England Model Engineering Society (NEMES).
The opening image of a Congreve clock is copyright © 1997 by Ray Bates, MBHI. With the exception of any material noted as being in the public domain, the text, encoding, and other images of this document are copyright © 1996-1998 by David M. MacMillan.
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