Before launching into the subjects raised by this watch, let me issue a warning that this isn't just any ordinary one-or-two-off custom-cased-and-dialed wristwatch. To appreciate this one we are going to venture into some obscure topics. I will try to summarize rather than send all off clicking away into the void, albeit with some loss of a completely informed presentation, and of much detail.
It is necessary to distinguish between watches receiving common COSC ("Controle Officiel Suisse des Chronometres") chronometer certification and those receiving Observatory certification or actually competing at either the Geneva or Neuchatel Observatories. Almost all of my information comes from Fritz von Osterhausen's book "Wristwatch Chronometers", and I have summarized quite a bit, for his presentation is very detailed, if not terribly friendly in the English translation.
The term "chronometer" began in 1715 with English watchmaker Jeremy Thacker, for a sea watch using a verge movement. John Arnold extended the use to pocketwatches in 1782 for those having spring or pivoted detent escapements. When the Swiss designed lever escapements with equivalent or better precision, the term came to indicate the high precision, rather than the escapement type. In 1925, the Swiss Association for Chronometry said: "A chronometer is a watch which has received a certificate from an astronomical observatory".
Observatory testing and competitions
Chronometer competitions began in Neuchatel in 1866, and Geneva in 1873, and ended in Neuchatel in 1975, and Geneva in 1967; for wristwatches, competitions ran from 1945 through 1967. Manufacturers would submit one or several specially prepared watches for competition, sometimes the same one(s) for many years running, and these were never meant for sale. The purpose of these tests was to spur competition and innovation, disseminate technical information and discoveries to advance chronometer research, and of course to provide publicity and acclaim for the manufacturer in selling their more ordinary watches.
Competitors works were grouped by size ranging from category A (43-70mm), through C (under 38mm). In 1944, category D was added to accomodate wristwatches, that being those under 30mm diameter, or 707 square mm for formed movements. Prior to being allowed to compete, entrants were tested, and those meeting the rigorous standards were awarded the certification, and were eligible for actual competition. Testing took 44 days, encompassing 5 positions, 3 temperatures and 9 periods of from 1 to 5 days. Ten wristwatches were submitted in 1945, and 8 received certificates; the peak was reached in 1964 when 152 watches were certified, and decreased to 88 by the last year of competition (1967). All in all, to receive certification a watch had to meet or surpass standards in 11 categories, ranging from "mean rate variation, each period" (1.5 seconds) through "mean rate variation with respect to position change" (3 seconds). During the entire 23 years of testing, 5093 wristwatches were submitted for certification, and only 3253 were passed, about 64%.
Just a few manufacturers participated, and only Omega and Patek did so every year. The others were: Rolex, Zenith, Longines, Movado, Vacheron & Constantin, Ulysse Nardin, Cyma and Favre-Leuba, along with numerous independent professional watchmakers.
The system of official Swiss testing agencies certifying the performance of individual watch movements to a certain (high) standard is an entirely distinct and parallel undertaking. These do not involve competition, and the standards are therefore fixed, and much less rigorous. COSC certification is strictly a commercial matter; for example, during the span 1974 through 1988, although not the best years for mechanical watches, over 4 million watches received COSC certification. The office in Bienne opened in 1877, followed by several others before the turn of the century. These were largely independent enterprises, although they often followed the same guidelines and/or came under the governance of their city, and each ws associated with a watchmaker school. Not until 1973 was control consolidated under the COSC in La Chaux-de-Fonds, with branches in Bienne, Geneva and Le Locle. As FvO states "Everybody will be able to wear a "Bureaux Officiels" (the predecessors to the COSC) tested chronometer wristwatch, but, with few exceptions, nobody will be able to wear an observatory tested watch."
The Peseux 260 movement was designed specifically for observatory competitions, and its total production of some 3300 units was spread over nearly a quarter-century, ending in 1970. This picture shows a Peseux 260 incorporated into a Ulysse Nardin watch, and cased appropriately for competition. This would appear to be an earlier version, as it has a steel hairspring and cut balance, rather then the blue Nivarox 1 spring and solid balance of the Be-Ba.
At 13 lignes (just under 30mm) diameter, the 260 is at the size limit for its category, and the 13.5mm diameter balance is obviously as large as possible. Likewise, the barrel is over 12mm diameter to allow for the longest possible mainspring and consistent torque supply. Other refinements appropriate to a movement of such narrow application are not obvious, but the finish of the bridges, teeth and screws is exemplary, if not especially decorative. This particular movement has been custom-cased and wonderfully dialed, and provided a neat display back. I have no evidence that the Be-Ba's movement was ever submitted for testing, or entered into competition, but even if, as with the street-legal homologation of certain racing automobiles, it turns out to be just intended for a well-informed consumer, it is still a great, pure-bred engine dressed in beautiful if appropriately subtle clothing. As of the moment, the origins and meaning (if any) of the appelation "Be-Ba" remain charmingly undetemined.
I wish to offer my special thanks to Franco dG. and Matthias S. for illuminating the significance of this watch, and to ThomasM and friends, including Bill S, John D, Curtis T and Carlos P who have generously shared of their knowledge and time in helping me prepare this article, including the special efforts of AHCI member Andreas Strehler.