As opposed to regular tourbillon regulators in which the carriage is fitted in a plate and secured by a bridge, iii flying tourbillons, as invented by Alfred Helwig, and produced raider his direction in the Deutsche Uhrmacherschule of Glashiitte, if the lower bearing of the carriage is fitted in the plate, in the regular way, the upper bearing is fitted beneath the carriage, and, on the top of the carriage, there are neither pivot nor bridge. The carriage is so thin and so light, that Helwig, in order to demonstrate the robustness of this construction, hung a 200gr. weight to the carriage during eight days. The last sceptics were only convinced when the carriage was fitted hack in the movement for which it was made. Flying tourbillons made as masterpieces by the best pupils of the Deutsche Uhrmacherschule in Glashiitte, according to the principals and under the control of Professor Alfred IIelwig, represent the ultimate achievement in the making of revolving escapements. The few examples made at the Lange School can certainly be counted amongt the masterpieces of German horology. Only 14 pieces of this type were made on the pattern of Tourbillon No. 7 which was the prototype. They were all produced in the Deutsche Uhrmacherschule of Glashiitte, under the direction of the inventor, Professor Alfred Ilelwig. Now in the Museum of Time Measurement Beyer, in Zurich, the tourbillon No. 7, was made hi 1926 by I-lans Ape' who became professor in the Hamburg Uhrmacherschule of Altona. This pocket chronometer is fully described and illustrated by Kurt Herkner in Clasleiitte v.nrd Seine (Three, Herkner verlag, Dormagen, Germany, 1978, pp. 391-394. An another masterpiece made in 1931 by Willmar Fleck ( No. 24) under the direction of Alfred Helwig was sold by Antiquorum in Geneva on October 14, 1990, lot 473.