The Reason

In addition to being generally heavily over-engineered horology, the system of setting is unique to Jurgensen. Setting the time was made by opening the cover and pivoting the pendant bow towards the dial, then turning the crown would adjust the hands.

Founded by Jürgen Jürgensen in 1740 in Denmark , when Jürgen Jürgensen went into partnership with Isaac Larpent, under the name "Larpent & Jürgensen". Upon Jürgen's death in 1811, his youngest son Frederik took over the company and changed the name to "Frederik Jürgensen".  Jürgensen was sold to a company in the US in 1936, the watches were still produced in Switzerland until 1957. 

Please click on the images below to enlarge and to read additional information.

A 5 minute repeater with single push piece chronograph. The chronograph records up to 1 minute and the offset seconds has 5 incremental jumps in a single second. There are two trains in the movement and the watch is wound by winding the crown in both directions winding both barrels. One for the going train, one for the chronograph. Another aspect of this watch which makes it unusual is the setting of the hour is executed by tilting the bow towards the dial, then the crown adjusts the time instead of winding the mainsprings.

5 minute repeaters were first made in 1710 by Samuel Watson, the repeater strikes the hours and then the number of five-minute periods after the hour. The mechanism uses a low tone for the hours and a higher tone for the minutes. 

 A "foudroyante" hand, has a period of one second. Watches equipped with such a hand typically also feature a conventional seconds hand. The foudroyante hand can be central or in a sub-dial, and can be used for timekeeping or as part of a chronograph.

The 2 images below show the system how the setting mechanism works. On the left the bow leans forward pushing the 'T' shaped pin down, this then pushes the steel bar on the outer side of the mainplate on the right hand side image in-turn pushing down the return bar and sliding pinion into setting position.

On the inside of the bow as it enters the tube is a semi-circular section that pushes against the pin when it leans forward. 

The below video shows the interaction between the lower level of the escape-wheel and the star wheel next to it which pulses 5 times per second.

Watch lent for deconstruction by

Somlo Antiques