Berlin - Only a few of the eight trainees can stand up in the small, circular chamber as they listen to their instructor.

Michael Schillhaneck explains how the fantail turns the low room they are crammed into around its own axis towards the wind, while the windshaft and other levers assist in the movement.

The chamber is called the cap, and sits on top of an historic windmill in Berlin's southern suburb of Britz.

Up here, Schillhaneck is teaching his latest class, a group of five men and two women who are keen to take their first steps towards becoming certified millers.

Although modern, white power-generating windmills have become a normal sight all over Germany, there are still historic flour mills, too. Some were converted into homes, others into restaurants.

And several of the 900 historic mills which the local millers' association oversees in the Berlin region still grind flour.

The milling trade has long been extinct in Germany, but running technical monuments like the Britz mill operated by Schillhaneck need trained staff to maintain the mechanism.

Mario Cochius is a student on the 13th course currently training at the Britz mill. It is the only education centre for certifying windmill millers in Germany and offers a two-year training programme, at the end of which successful students are awarded official miller's diplomas by a Dutch examination committee.

Cochius, a trained electro-mechanic, read of the milling course in a local paper. He told his wife, a fitter and truck driver, about it. They signed up.

We do lots of crazy things," Cochius says. This is just what we needed. And it's better than slouching in front of the TV."

Among their fellow students are a teacher, civil servants and a restaurant owner. I'm interested in historic machinery," says Alfred Hermann von Luenen, who soon will retire. It's good to have a new occupation."

Once they are certified millers, the non-profit club running the mill hopes to keep them as volunteers. The club members grind grain into flour which is then baked into organic bread by a Berlin bakery.

Schillhaneck, himself a certified miller since 2005, teaches his first lesson on milling history in a draughty container at the foot of the impressive 20-metre-high mill with its 25-metre-wide blades.

Its bulging shape and white-framed windows give the mill an inviting, homely look which is far removed from that of its spindly power-generating modern cousins.

Over the next two years, the trainees will attend theory classes and gather experience on site twice a week. A field trip to the Netherlands, homeland of windmills, is also part of the course.

You should wear special millers' overalls," Schillhaneck says. They're tight-fitting, so you don't risk getting caught in the rotating machinery. Working in the mill, we can't just turn off the mechanism at will."

Milling can be a dangerous business. On the mill's second floor, two small doors open to the outside gallery circling the structure at four-and-a-half metres above the ground.

It is vital to chose the right exit, Schillhaneck explains - the wind wheel adjusts to the wind direction, and if you take the wrong exit, a blow from the powerful blades can be fatal.

Precise hearing also is crucial. The stones have to sing," says the teacher - that's when the space between bed and runner stones is just right. But if they're rumbling, there's the danger of sparks and a dust explosion.

Fire is the main menace to the historic building, where the brake wheel, shafts and gear mechanisms constructing its inner life are all made of wood.

The 18th-century equipment was put back in place in 1985, replacing a diesel drive that had been installed in the 1930s.

Some of the junior trainees still look on helplessly as they listen to Schillhaneck's explanations.

But they're determined to learn and revive a tradition which - in the from of simple rubbing stones - was born in Babylonia more than 6,000 years ago. (dpa)