In the words of the late Jean-Claude Sabrier: “Tourbillon pocket chronometers, undoubtedly the most original of all Houriet’s creations, represent the culminating point of his research on compensation balances and the isochronism of balance springs”.
Formerly in the collection of the legendary Theodor Beyer of Zürich, this superlative high-precision pocket chronometer is an early and remarkable tourbillon watch made by one of the great masters of Swiss watchmaking, Jacques-Frédéric Houriet. Made for DuBois et Comp around 1825, it is one of only seven known examples of this model and further preserved in excellent overall condition.
The workmanship and finish of this watch, as one would expect from one of the watchmaking “greats”, is simply extraordinary. Houriet was almost certainly the first watchmaker after Breguet, its inventor, to make use of the tourbillon regulator in his watches. Breguet had been granted a 10-year patent for his tourbillon regulator in June 1801 and therefore others were forbidden from producing and selling them until after 1811. However, Houriet, due to his exceptional skills, was chosen by Breguet himself to produce his pocket chronometers with tourbillon, the most elaborate of their kind.
For greater precision, in the present watch the tourbillon is coupled with an Earnshaw-type spring detent chronometer escapement, much less common than the usual lever found in most tourbillon watches and the one which Houriet considered preferable for obtaining the greatest regularity of rate. In addition, it is fitted with both of Houriet’s most iconic technical innovations – the “isochronous” spherical balance spring and his own version of the Réaumur thermometer. Technical virtuosity coupled with clarity and boldness of design have come together in this watch to create a mechanical masterpiece that is also extremely beautiful.
The spherical balance spring with which it is fitted enables it to be isochronous, meaning that the timekeeping is unaffected by fluctuations in the amplitude or swing of the balance as the watch goes from a fully wound state to a state of unwind. In other words, the frequency of the balance spring is independent of its amplitude. Houriet used the spherical balance spring in his watches from 1815 asserting that “….I had the idea of making balance springs that were spherical in form, in which the coils augment or diminish progressively with perfect uniformity”.
It is interesting to discover that Houriet’s technique for making spherical springs has survived, he employed a two-part mould onto which were adjusted five brass discs. He turned this system into a sphere flattened at the poles and traced a tread on it with a fusée engine.
Another fascinating aspect of the present watch is the inclusion of a thermometer. It was Houriet who first conceived the idea of fitting a thermometer to watches, in particular his tourbillon chronometers. Interestingly, it was Houriet’s pupil and son-in-law. Urban Jürgensen who justly claimed to be the inventor of the metallic pocket thermometer constructed in 1801. The idea was then improved upon by Houriet and incorporated in his finest timepieces.
After 1818, Houriet adapted a new numbering system for his watches and chronometers. These pieces were almost never signed with his name but, as with the present watch, can be identified by the punchmark “FH” on the pillar plate along with the watch number.
Jacques-Frédéric Houriet (1743-1830) was a remarkable horologist considered to be the father of Swiss precision watchmaking. He knew or worked with most of the most eminent horologists of his time. His research on compensated balances and the spherical balance spring allowed him to develop and perfect the most precise chronometers of his day. In addition, he successfully solved the problem of the influence of magnetic fields on the rate of chronometers. He was apprenticed to his uncle, Daniel Gagnebin, at Renan, and later to the celebrated Abraham-Louis Perrelet, the inventor of the self-winding watch. In 1759, at the age of sixteen, he and his elder brother, an engraver, moved to Paris. Between 1761 and 1768 he studied with some of the leading French horologists, notably Breguet, LeRoy, Berthoud and Romilly and was the first Swiss watchmaker to make tourbillons. Antide Janvier, one of the most eminent horological minds of all time, considered Houriet an “artist worthy of emulation under the double relation of instruction and responsibility.”
He is best known for his pioneer work in the construction of marine and pocket chronometers and in particular for his experiments with isochronism of the hairspring or helical spiral and the effect of gravity or magnetism on the balance and escapement. He supplied a tourbillon chronometer to William Parry for the 1819-21 North Pole Expedition which was especially constructed for anti-magnetic properties. Houriet also trained the Danish watchmaker Urban Jürgensen on whose work he had a great influence and who became his son-in-law.