Breguet Tourbillon and Abraham Louis Breguet

Born in Neuchâtel, Switzerland on January 10, 1747, Abraham Louis Breguet secured his position in history as the father of watchmaking through his creations and technical wizardry. At an early age, he traveled to Versailles and Paris to study about clock making. At the time, the French King Louis the XVI attracted talent that was the best in virtually every field of technique and art. After spending 13 years as an apprentice and following his marriage to the daughter of a prosperous French bourgeois (her dowry provided the "financing" which allowed him to open his own workshop), he founded the Breguet Company in 1775 in the Île de la Cité, Paris. The relationships Breguet had made with scholarly people during his apprenticeship as a watchmaker soon paid off with spectacular results. Following his appearance to the court, whereupon Queen Marie-Antoinette is said to have grown fascinated by Breguet's novel self-winding watch, King Louis XVI bought several of his watches. He presented one of them to the mariner Bougainveille, who was in the process of organizing his great expedition to the North Pole.

Word spread and very soon kings, princes, and European aristocrats were buying his watches. Breguet became a household name in Europe during the 18th to 19th century and the name stuck as a common reference for timepieces, just like FedEx for courier service or Kleenex for napkins. From 1793 to his death in 1823, Breguet proved himself to be quite the technical genius that he was and he continuously enhanced his technical abilities and created many important inventions. In short order, he perfected the self-winding movement invented by Abraham Louis Perrelet in 1770; invented the overcoil balance spring which is known by his name today; came up with Breguet hands and Breguet numerals, invented shock resistance for balance bearings (prior to this, most pocket watches were badly damaged if they fell to the floor); built the first watches with perpetual calendar and moonphase indication, developed la repetition, a repeating pocket watch which chimed on demand (back in those days it was necessary to tell time in the dark); and perfected extra flat watches. His labor culminated in the grand finale of his work: the Tourbillon (1801).

In his application for a patent, the famous watchmaker lists several advantages of the tourbillon, which he summarizes below:

"By means of this invention, I have succeeded in cancelling through compensation the anomalies caused by the different positions of the centres of gravity of the regulator movements, to distribute frictions on all parts of the circumference of this regulator's pivots and of the holes in which these pivots move. This is to allow the oiling of the friction surfaces to always be even, in spite of oil coagulation, and finally to cancel many other causes of error influencing movement accuracy. This could only be attained until now by constant trial and error and often even without any certainty of success."

Through these inventions, Breguet secured the success of his firm under the rule of two Bourbon kings, three governments of the First Republic and the reign of Napoleon. In fact, Napoleon was one of his most loyal customers.
An amusing story is told in which Napoleon, while in the heat of battle, wanted to see the time on his pocket watch right away, without sacrificing the benefits of the cover. So, right then and there, Napoleon unceremoniously cut a small viewing hole in the front cover. This gave him an unobstructed view of the face and hands! And so the half-hunter pocket watch was born.
Of all his inventions, perhaps the invention Breguet is most famous for is the tourbillon. Even with today's advanced technology, the tourbillon can only be built by the most skilled watchmakers. Breguet theorized that the effects of gravity on a pocket watch (pocket watches were almost always carried vertically) led to deviations in timekeeping. He wanted to rule out all differences of position with the tourbillon.
Consequently, he developed what was essentially a small "clock within a clock", meaning that the balance and escapement turned on a common axle within a revolving cage once a minute, for example. This elminated most deviations caused by differences in position and allowed many watches to attain chronometer-like accuracy.
But in actuality, was Breguet right in saying that by placing the escapement and balance wheel in a cage that rotates continuously, his tourbillon equipped watch balances out the effects of gravity, thus achieving greater accuracy? Let's see...
The escapement of a watch placed in the horizontal plane ("pendant up" or "dial up" positions) will have little variations in the frequency of its balance wheel as the changes in the escapement's center of gravity are negligible. Therefore, one can deduce that the tourbillon does not correct the rate variations in the horizontal position; in fact, Breguet was careful not to say this in his application for a patent. On the other hand, a watch placed in the vertical positions (crown left; right; down; or up) may have zero to large variations in the frequency of its balance wheel as a result of changes in the escapement's center of gravity. Thus, for example, in vertical position one, the watch may have a variation of 2 seconds/day, in vertical position two, 4 seconds/day, and yet in vertical position three, 0 seconds/day. As a result, a watch laid flat at night and always placed in the same vertical position during the day does not provide better results when equipped with a tourbillon. It's more the contrary that is true, because in a vertical position the tourbillon watch gives an average rate while the watch without a tourbillon gives only the rating result corresponding to the position it occupies.

The possible advantage of the tourbillon then manifests only if the watch without tourbillon remains in any one vertical position during the day. The performance advantage is even further nullified by the fact that wristwatches spend a less predictable amount of time in less predictable positions. The actual moving of your wrist acts as a tourbillon for your wristwatch! When you wear them, they occupy an infinite variety of positions and their rating results give an average of this constant motion.
Breguet was correct in observing that the regular functioning of a watch was influenced to a great extent by the watch's position. Therefore, he concluded that the cause of such variations was due to the effects of gravity on the escapement and he mentions this in his patent application. However, it never occurred to him that perhaps these variations were due to some components in a watch's movement. 19th century Breguet constructed watch components of such high level that he considered (but was only partly right) the perfect balancing of balance wheel and balance spring to be a given. Eventually it was discovered that the real problem was the balancing of the balance wheel and, only in second place, its friction. For a watch's operation to be consistent (i.e. "accurate"), the balance wheel must be perfectly round and poised (i.e., in balance, without heavy points on the wheel) and the spring must extend and contract symmetrically from the exact center of its coil.

Of greater importance to watchmaking at the time of the tourbillon's development, was that Breguet's invention produced watches requiring less frequent maintenance. Because 19th century portable watches were almost exclusively pocket watches, they were frequently carried in coat vest pockets and held constantly in a vertical position. Carried in this fashion, the balance wheel pivot rested only on one side of its seat and consequently, friction - which was considerable given the materials used, the internal surface finish, and the lubricants adopted at the time - caused a strong wear on both seat and pivot and made frequent servicing necessary.

In a letter addressed to his son, Breguet wrote:
I succeeded in elminating the anomalies due to the different positions of the center of gravity and movements of the balance, by distributing the function over all the pieces of the balance and pivot holes, so as to assure an equal lubrication of the friction surfaces.
The innovation introduced by Breguet, consisting of a continuous rotating cage supporting the balance wheel and escapement, allowed distribution wear over the whole circumference of seat and pivot to achieve better lubrication results and assured a more regular working performance. However, nowadays, with the development of advanced lubricants and better surface finishing of watch components, the need for a tourbillon for watch maintenance is rather a moot point.