Description: THE PERFECT MARINE BALANCE LONGITUDE CLOCK "BALANCIER MARIN PERFAIT" (BMP), circa 1685 This is the earliest known longitude timekeeper. Its historical and horological importance can be summarized by: - It is the earliest known longitude clock in existence - Its mechanics inspired Harrison and likely contributed to his ?20,000 award from the English Board of Longitude for H4υ1 - It is the only surviving Huygens longitude timepiece - It is the culmination of Huygens lifetime of experience - It is the earliest surviving clock with an attempt to create a frictional rest escapement - It is the earliest surviving equation of time clock - It is the earliest known clock employing disc bearings (anti-friction rollers) - It is the earliest or one of the earliest known continental clocks with maintaining power INTRODUCTION Inmodern horological literature, this clock is mentioned once and only briefly by John Leopold in his address at the 1993 Longitude Symposium at Harvard: "...in March 1695, Huygens had an existing clock (with equation of time) converted to the new balance, but about this we have no further details. ... A publication on the new clock, which he had announced shortly before his death, was never written".υ2 Leopold based his remarks on Huygens' last surviving letter,υ3 written in March of 1695, in which Huygens writes to his only brother about converting an existing three-foot pendulum clock with equation of time to his new invention. Huygens employed two new concepts in this clock: his Perfect Marine Balance and a new form of escapement apparently also invented by him. The Perfect Marine Balance is an unusual union between a pendulum and a balance consisting of a largefoliot (balance) with a small pendulum affixed to it. The concept sounds strange but, as Huygens proved mathematically, it is isochronous.υ4 The new escapement, invented by Huygens, is the first attempt to create a frictional rest escapement. The impulse is given to a chronometer-like pallet by one escape wheel with locking via the second wheel. KNOWN HISTORY OF THE BMP2 CLOCK Early 1680s - 1695. In the possession of Huygens. 1695-1754. In the Huygens family. 1754 Auctioned by Huygens family (Oeuvres Complètes de Christiaan Huygens, vol. 15, pp. 19-21). 1754-1980s Whereabouts unknown. 1980s-2002 Time Museum, Rockford, USA (Inv. 727). 2002 Auctioned at Sotheby's Time Museum Sale on June 19, lot 129, misattributed to Sully. CLOCK IN THE TIME MUSEUM The clock was purchased by the museum in the 1980s. It was an inexpensive purchase; the cost was $20,000υ5.The clock did not work; the seller thinking that it supposed to have a pendulum, attached a mock short pendulum to one arm of the foliot via its cylindrical weight. The locking cylinder was slid to the impulse pallet. Who would have thought then that it was one of the most important clocks in the museums collection? ATTRIBUTABILITY TO HUYGENS - Only Huygens (later Sully) made Perfect Marine Balance clocks. The fact that the clock was meant for a Perfect Marine Balance is evident from the arrangement of the plates. The 4PthP and the 5PthP wheels are bridged to make extra space, a space that does not make sense for any other arrangement than Perfect Marine Balance. - Huygens wrote that he converted a pendulum clock to fit his new invention.υ6 This clock used to be fitted with a pendulum. There is clearly a slot for a pendulum as well as for the pendulum locking. -Huygens wrote that his clock had equation of time mechanism. This is the only such early clock with equation of time in existence. - Only Huygens and Sully made clocks with the Perfect Marine Balance. This clock was not made by Sully (see below). That leaves only Huygens. THE ISSUE OF PAST MISATTRIBUTION OF THE CLOCK With the dispersion of the Time Museum the clock was entrusted to Sotheby's to be auctioned. Sotheby's in the June 19, 2002 catalog attributed the clock to Sully because "...the design of the movement of this complicated clock incorporating anti-friction rollers in the escapement suggests that it may have been made by Henry Sully". Sotheby's apparently was under the impression that the friction rollers were used only by Sully. In fact, anti-friction rollers were invented and used way before Sully. They were well known to Huygens.υ7 They were even known toLeonardo da Vinci who drew them in 1494 (Codex Madrid I). Clearly, the attribution of the clock to Sully based on his supposed sole use of anti-friction rollers has no grounds. THE CONCEPTION OF THE BALANCIER MARIN PARFAIT (PERFECT MARINE BALANCE) After the failures with pendulum-based longitude clocks, Huygens put his efforts into devising a balance marine clock. Knowing the shortcomings of the balance spring, he looked for another solution. He found one unexpectedly when he discovered that a combination of a pendulum attached to a balance is isochronous. He proved this mathematically and called the contrivance balancier marin parfait. The first such clock, BMP1, was entrusted to Barent van der Cloese to be built, but Huygens did most of the final adjustments. Landgraf Karl, who learned about it asked Huygens to make one for him but Huygens politely declined.υ8 It isplausible that Huygens changed his mind and the new clock, this one, was meant to be given to the Landgraf, which would explain the exceptionally elaborate case. In 1694 Huygens decided that his new invention will be based on two-arm balance (foliot)υ9 and a single small pendulumυ10. These two features in 1695 he implemented into this clock, the BMP2. THE PERFECT MARINE BALANCE OF THIS CLOCK AND THE ESCAPEMENT The balance or, rather, a foliot is placed in the back of the escapement mechanism. It consists of two cylindrical weights placed on threaded ends of the foliot ends. In the middle there is a short brass pendulum swinging between curved cheeksυ11 with a ribbon suspension. At the top there is a nut for adjusting the apparatus. The escape wheel has two wheels, each of 15 teeth. The smaller one gives impulse directly to the balance via a largepallet placed on the balance arbor, the same as in a chronometer or duplex escapement. The large wheel is for locking. Huygens needed to find a place for the pendulum. Outside the plate was not possible due to the balance (foliot). Therefore, he caged the 4 wheel and the seconds wheels, which gave him enough space for the pendulum between the plates. There are two sets of anti-friction rollers (disc bearings), two large ones in the back and two small ones in the front. The case is based on a rectangular frame, almost exactly as in a Huygens drawing of his pendulum clockυ12. All observations support dating BMP2 to the 1680s. Quoting Jean-Dominique Augarde,υ13 "until the end of the eighteenth century, the great cabinet-makers who were responsible for the glory and the fame of France in this domain were not native born, ... most distinguished came directly from thecountries situated within the ancient boundaries of the German Holy Roman Empire, especially from the Rhineland, the Dutch provinces, and Flanders". Some of the artists must have stayed in the Dutch provinces: Huygens would not have had a problem finding one. The mask of Apollo within sunrays at the top of the clock is typical for the period and many similar ones can be found such as a Louis XIV decoration from a panel in the Louvre. It represents the Sun God to whom Louis XIV likened himself. The central sunburst pattern also alludes to Louis XIV, the Sun King. THE SECRET LOCKING OF THE CASE The clocks case is constructed in such a way that, unless one is quite familiar with it, it is impossible to see anything inside or even quickly take it apart. Even if one figures out the role of two small pin holes which let the front panel open, one needs a screwdriver and a good half anhour to get to the movement. This is entirely consistent with the research of the two foremost Huygens experts: John Leopold and Prof. Michael Mahoney. In addition to Leopolds statement, Huygens work in establishing longitude by timepieces was a matter of some secrecy, Mahoney joins him with ...Huygens jealously guarded the fortune that might result from his inventions.υ14 The maintaining power is of the bolt and shutter form acting on the center wheel. It is one of earliest designs known. Few clocks by Fromanteel from 1665-70 are known with a similar arrangement.υ15 THE EQUATION OF TIME Since this is the earliest surviving clock with equation of time, it deserves detailed description. The first known equation of time clock was built by John Fromanteel to the specifications of Nicholas Mercator, who showed it to the Royal Society in 1666 and then presented it tothe king. In France, Pierre Gaudron claimed that his father built one in 1688, which was the first in France. These have not survived, or if they have, their whereabouts are unknown. This clock is from the same period and has survived. The equation is based on an annual calendar wheel which is driven by a worm mechanism starting from an endless screw driven directly from the hour wheel, which has a worm gear milled on its thick sleeve. This is inherited from not much earlier Renaissance mechanisms. CONCLUSION The clock is one of those rare, important objects from the past that has changed our understanding of the history of the technology. Many of them have been lost forever. This one was in front of our eyes from the 1980s but wrongly attributed. We now know that it is Huygens Balancier Marin Parfait, the oldest longitude clock in existence, the inspiration for Harrisonsprize-winning longitude clock, and the oldest surviving equation of time clock. While Huygens premature death prevented him from finding the ultimate solution for longitude, he came very close to this discovery. Eventually, it was captured by John Harrison (who, coincidently, was born the year Huygens died) who found the answer in metallurgy (bimetallic compensation), but it was Huygensoriginal work that guided Harrison through the mechanics.υ16 These mechanics achieved their pinnacle in this newly discovered Huygens clock, the BMP2, the last one he ever built, partially with his own hands,υ17 the one to which he applied his lifetime of experience, and which eventually was to lead to the solution of the longitude problem. 1W. S. Laycock in The Lost Science of John "Longitude" Harrison (1976) stated: " ...the Englishman [Harrison] owed far more to his Dutchpredecessor than he either knew or would admit". 2 The Proceedings of the Longitude Symposium (Cambridge: Harvard University, November 4-6, 1993), p. 112. 3 Oeuvres Complètes de Christiaan Huygens (farther O.C.), vol. 10, no. 2891, pp. 709. 4 And later by C.A. Crommelin, published in Les horloges de Christiaan Huygens, Bulletin No. 61 of the Musée National d'Histoire des Sciences, Leiden. 5 Thanks to Patricia H. Atwood for this information. 6 See note 3. 7 O.C., vol. 18, pp. 571-91. 8 Huygens letter to Alexander Rolas de Roisey, the Chamberlain to the Prince. O.C., vol. 10, no 2878, pp. 684-5 9 O.C., vol. 18, p. 572 10 O.C., vol. 18, p. 576 11 Following his 1693 discovery of involutes of circles, Huygens specifically described the suspension cheeks as involutes of circles, not cycloids. 12 Christiaan Huygens, Horologium Oscillatorium, 1673. 13 Jean-Dominique Augarde,Les ouvriers du temps, Geneva, 1996. 14 J. H. Leopold, The Longitude Timekeepers of Christiaan Huygens, The Longitude Symposium, Harvard University, 1993. Michael S. Mahoney, Christian Huygens: The Measurement of Time and of Longitude at Sea, in Studies on Christiaan Huygens, ed. H.J.M. Bos et al. (Lisse: Swets, 1980), pp. 234-270. 15 Longcase clock ca 1670 in the G. Marsh Collection, Winchester, England; table clock in the Prestige Collection; longcase clock ca 1665 in the British Museum (inv. CAI-2099). 16 W. S. Laycock, The Lost Science of John Longitude Harrison (Ashford, Kent, 1976). 17 Judged by the fact that Huygens worked on previous clocks himself; in 1683 he made a model for his torsion pendulum. For his first Perfect Marine Balance, he made a balance himself and experimented with different types of chains. O.C., vol. 18, pp. 546-561 and 592-96. Cond.: Case: very good. Dial: very good. Movm.: very good, restaurations, capable of running.
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