Just noticed this to be auctioned today:
Seemingly simple. Unless one flips it over:
The auction text says
An important Glashuette deck watch of the "kaiserlichen Kriegsmarine" ("German Imperial navy") with carousel · sold 1908 for 320 Marks to the Chronometer Observatory in Kiel
Case: silver · engine-turned · emblem with the engraved Imperial Crown, "M" and the figures "658" of the "Kaiserlichen Marine" (Imperial Marine) · case design "Jürgens" · silver dome · gold hinges Dial: enamel · radial Roman hours · sunk seconds · blued spade hands Movm.: 2/3 plate movement · frosted · gilt · blued screws · carousel revolving in 52,5 minutes · nickel steel gold screw compensation balance · blued hairspring · very finely engraved balance cock · index spring fine adjusting device · gold lever and -escape wheel · set diamond endstone on balance
"Carousel" watches are a design by the Danish watchmaker B. Bonniksen, who registered the patent in 1892 in England. His intention was to create a compromise between the "expensive" tourbillon and a normal chronometer - and he actually achieved better results with his carousel than some of the tourbillons. In 1899 Richard Lange improved the design and received a protection of utility patents D.R.G.M 121267 for it. The escapement in a carousel with auxiliary seconds turns around itself in 52,5 minutes, and thus avoids the variation caused by gravity.
Lit.: "Die Lange-Liste" by Martin Huber, Munich 2000, page 103f.
Detailed description and illustration in:
"Glashuette und seine Uhren" by Kurt Herkner, Dormagen 1978, page 102ff.
(descriptive text and pictures courtesy of auction house Dr. Crott, Frankfurt, Germany)
A very special piece!