Flying Tourbillon
As opposed to regular tourbillon regulators in which the carriage is fitted in a plate and secured by a bridge, in flying tourbillons, as invented by Alfred Helwig, the lower bearing of the carriage is fitted in the plate in the regular way, the upper bearing is fitted beneath the carriage, and the carriage is built around free (flying) arbor. On the top of the carriage, there is neither pivot nor bridge. In the early 1920s Albert Helwig (1886-1974), technical director of the Deutsche Uhrmacherschule, invented what is now commonly known as a flying tourbillon: "?My idea of constructing the free-standing cage that is without a bridge, was to make a tourbillon as flat as possible ? The weight of the cage is only 700 milligrams; no one believed that it would be strong enough. Therefore, I tied a string on one side of the cage and another one on the other side but with a weight of 250 grams. I then hung this in the display case at the entrance hall to the Deutsche Uhrmacherschule and left it hanging there for four weeks, which stopped all critics?" Helwig made a few and some, including the present watch, were made by his students under his supervision. They were magnificent horological pieces of machinery. In one of his letters he wrote: "?Several of my students have built tourbillons in the school under my guidance at their own expense. We all promised each other never to sell them and if at all then not below the current value of three kilograms (over six pounds) of pure gold?" One of his talented students wasWoldemar Fleck, who made this masterpiece with Helwig in 1931. According to his son, he held on to the watch until his death. Flying tourbillons were made as masterpieces by the best pupils of the Deutsche Uhrmacherschule in Glashütte, according to the principles and under the control of Professor Alfred Helwig, represent the ultimate achievement in the making of revolving escapements. The few examples made at the Lange School can certainly be counted amongst the masterpieces of German horology. To commemorate these achievements, in 1999 Lange introduced a new wristwatch model, called "Helwig" employing this type of flying tourbillon.
Anibal-Brass Guillaume Balance An alloy invented by the Nobel prize winner Dr. Charles Edouard Guillaume, it exhibits unusual properties, both in terms of thermal expansion and in changes in elasticity. These properties are very different from those of two other famous alloys invented by Guillaume, Invar and Elinvar. Around 1900 Guillaume attempted to eliminate the so-called middle temperature error caused by the fact that the change of rate in a timekeeper with a steel-brass bimetallic balance is approximately a linear function of temperature, while the change of rate caused by change in elasticity of a balance spring is approximately a quadratic function. Thus, it equals zero at only two temperatures, causing secondary error. Countless attempts were made to eliminate middle temperature error, usually by means of auxiliary compensation devices. In 1899, Guillaume noticed that steel with an addition of 44.4% nickel had a negative square coefficient of thermal expansion. This alloy, combined with brass in bimetallic lamina, makes its expansion close to quadratic. Balances with bimetallic rims made of anibal and brass are usually called Guillaume balances, or, as their inventor called them, integral balances.When combined with special balance springs, they exhibit remarkable temperature stability, on occasion not exceeding 1/50 second per day at 1oC.