Arnold & Son Tourbillon Chronometer No.36 Tribute Edition

Arnold & Son Tourbillon Chronometer N°36: In The Footsteps Of James Cook

Only a handful of brands like Arnold & Son can historically claim to have made a major contribution to the development of watchmaking in the Age of Enlightenment and beyond. One of the pieces having participated in that development is marine chronometer no.1/36, the forefather of all subsequent Tourbillon N° 36 chronometers. All aboard!

By Vincent Daveau

John Arnold (1736-1799), following in his father's footsteps as a clockmaker and apprenticed by his gunsmith uncle, William Arnold, embarked upon his research very early on, with the purpose of producing a timepiece aimed at assisting mariners at sea in accordance with the specifications of the English Board of Longitude. The instrument had to be, above all, easily reproducible so as to reduce costs and increase quantities substantially for it to become widely available to the whole of the British Navy. It may seem incongruous, but in England in 1770, just as the industrial age was dawning, everything had still to be invented.

The rule of iteration

John Arnold, a true man of the Enlightenment, needed to keep a watchful eye on every innovation proposed by the designers of his day. As a trained technician, he knew that the simpler the movement and the more efficient the escapement, the greater the likelihood of the timepiece being easy reproducible and competitively priced.

Building on these reflections and entering into the competition in the 1770s alongside other brilliant watchmakers to create the ultimate timekeeper, Arnold succeeded in just one year in developing three totally original on-board chronometers. By comparison, it had taken Larcum Kendall two years to produce its K1, a copy of the H4, the model that had earned John Harrison the 20,000-pound prize awarded by the Board of Longitude.

At the time of their launch, his detractors were highly critical, as absolute precision was still lacking, but its ease of manufacture and reproducibility paved the way for his reputation. Virtually the only one in the market and capable of fast production, he sold his products for princely sums to seamen or scientists eager to possess their very own instrument capable of keeping accurate time aboard their ships or on long expeditions.

With a virtual monopoly on the situation, he thus ignored the criticism from watchmakers who were unable to rival him. However, in order to perfect the ideal mechanical arrangement, the one instrument that could satisfy mariners' needs, Arnold would have to try out more new types of escapements, and invent isochronous balances and balance-springs that were insensitive to temperature variations. For this reason, he developed many prototypes, each one different from the next, living off his sales which he sold in order to make a living (or which his customers begged him to sell).

Finding the ultimate solution

Before producing in quantity, the ideal construction needed to be found, along with the corresponding number of prototypes. On this basis, all the pieces created by John Arnold after 1770 were different, but still nonetheless tended towards a standardised construction procedure. The result was that in 1773, he produced his first watch for use on board ships equipped with a pivoted detent of his own invention. Rather satisfied with the results, he lent it to Captain Phipps for his expedition to the North Pole.

The new escapement, which was comparatively easy to copy for anyone wishing to do so, was so successful that John Arnold filed a patent for the entire assembly (pivoted detent, helical balance-spring and spiral compensation curb).

The hour was fast approaching when a solution permitting the series production of a reliable timepiece would finally be found. With its double T balance, pivoted detent and robust construction, chronometer no. 1/36 broke the record for precision.

Built in 1778, the timepiece was subjected to a 13-month trial at the Greenwich Observatory in 1779 and beat all records for precision at the time. Following this success, the term "chronometer" was coined for this type of precision watch in common parlance and texts. John Arnold produced between 10 and 12 more or less identical pieces of these chronometers. All were based on patented solutions, some, for no apparent reason, had reliability issues. The reason for the loss of accuracy was attributed to premature ageing of ultra-fine oils of animal origin.

Replicating a rare achievement

In homage to its first historical chronometer, Arnold & Son decided to create the Tourbillon Chronometer no.36 wristwatch as a tribute to the first historical instrument of its kind. In accordance with classic British watch construction, the instrument's calibre has been built in such a way as to ensure that each mobile part (wheels or pivoting elements) can be mounted in their own bridge (no less than 13 in total), which the workshop craftsmen then cuts away aesthetically to alleviate the visual weight of the construction. The architecture ultimately allows the viewer's gaze to delve deep into the very heart of the mechanical arrangement and obtain glimpses of some of the components inspired by those originally used by the founder of this tremendous undertaking in the 18th century.

Clearly, such an exquisite gem required a tourbillon cage. One thing that is often overlooked is that the first tourbillon made by Abraham-Louis Breguet in the early 19th century was, in fact, based on Arnold's marine chronometer (no. 11 built in 1770 with pivoted detent, then modified to accommodate the tourbillon cage fitted with Peto's cross-detent). Peto was Arnold's closest friend and even sent his son to train with the watchmaker in 1792. In this construction, with its manually-wound A&S 8600 calibre developed entirely in-house, the cage weighs a few fractions of a gramme and comprises around 58 parts.

This highly accurate regulating organ carries the required COSC certification. Likewise, the movement boasts a level of finishing commensurate with that practiced back in the time of the company's founder. Thus, in order to replicate the hand-frosting or grainage so characteristic of mercury-gilded parts, the manufacture finely sandblasts the surfaces. The red gold version sports a grey NAC treated bottom-plate and palladium-plated bridges, while the steel model carries NAC-treated bridges and a black DLC bottom-plate, which was deemed a more contemporary finish. Similarly, for the sublime finishing touch, the bottom-plate features the traditionally mounted jewels in polished white gold chatons, while the screws are also treated in the traditional manner, and the wheels in the gear train driven by the double barrels, guaranteeing a power reserve of 90 hours once fully wound, are embellished with circular satin-finishing and their edges are chamfered and polished. 

A splendid study in symmetry, the Tourbillon Chronometer no. 36 is first and foremost a masterpiece of fine watchmaking dedicated to scrupulous accuracy. Symbolically, it reminds us that the English watchmakers were the first to focus on pure precision and that John Arnold was the first watchmaker in the world to understand the importance of producing timepieces that were not only accurate, but also easily reproducible to satisfy the many mariners needing to pinpoint their position at sea both easily and efficiently. With its dynamic approach and its austere appearance nonetheless harbouring some intricate complications, this piece at once lives up to the name it carries and pays a worthy tribute to English watchmaking, which, let it not be forgotten, dominated the industry throughout the 18th century and a good part of the 19th.

(Photography by Pierre Vogel)

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