A. Lange & Sohne Datograph Perpetual Tourbillon (740.036)

David Chokron: Last year you introduced a huge watch, the Lange Grande Complication. What's your big launch this year?
Wilhelm Schmid: It's a tough call. The 1815 Tourbillon and the Richard Lange Perpetual Calendar "Terraluna" would both do the job as a centrepiece for the booth. In the end, we opted for the latter, for the simple reason that it truly epitomises A. Lange & Söhne in every possible way. First of all, the dial looks like a perpetual calendar, but it only reveals its full beauty for the owner because you have to flip the watch to discover the moon phase. That's very A. Lange & Söhne, since we don't do things to impress others, but to please our customers. And of course, it brings together a lot of technologies we have accumulated over time within just one model. From the Lange 31 we took constant force and a long power reserve, while the jumping discs were picked up from the Zeitwerk - a model that is all about managing energy and powerful disc movement; and finally the moon phase boasting 1058-year accuracy is borrowed from the 1815 Moon Phase.

Many of your watches are under 40 mm. Yet, every once in a while, you release a very large piece like the "Terraluna". Why is that?
For us, size and space are determined by the movement. One Clearly, if you want massive power reserve, constant force escapement and displays on both sides, you need a certain height. If you take no shortcuts with the watch and if you keep it robust, you get a large piece. For me it's more important to ensure sustainable quality than to have a more seductive, thin watch.

What about the second star of this year, the 1815 Tourbillon?
The tourbillon itself is a mechanism that enhances the accuracy of the watch. It's a matter of seconds per week. Yet because tourbillons can't be stopped, simply setting the time can result in a one-minute loss of precision, which immediately disturbs the timing of the watch. We have actually launched a number of tourbillons over the years, and since 2008, we have been building all our tourbillons so that that you can stop them running. We now use our zero-reset mechanism on top of the tourbillon cage. For added convenience, pulling the crown makes the seconds jump to zero automatically, which is the easiest way to set time properly.

This zero-reset mechanism works a little bit like a chronograph, doesn't it?
There is one huge difference. These little tourbillon cages are not only very light, they're also very delicate, and they don't like pressure. So we have to be extra careful.

A. Lange & Söhne was under the supervision of M. Jerôme Lambert when he was CEO of Jaeger- LeCoultre. He has now moved to Montblanc. Does that mean you have full autonomy?
I consider myself extremely lucky to have worked with Jerôme Lambert, who has a thorough knowledge of watches. He ,helped a good deal, particularly in the beginning.

You are building a new manufacturing facility in Glashutte?
We now have 670 staff and we are cramped. We are spread between three buildings, and those buildings are landmarks, which means we don't have the right to tamper with them. So we're adding a new facility. It will regroup most of our manufacturing staff and our machines. It will also be energy efficient. We are using a geothermal well to regulate temperature, and a shutter system that allows for maximum light while not letting the summer heat in.

Won't moving from the old to the new facility disrupt production?
We'll be doing that gradually. And as for the machines, we keep adding more, so we're used to moving them around all the time.