The Naked Watchmaker

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.

The time and chronograph hands. All made in steel and then blued. Extremely fine and delicate and synonymous to the DNA of Jurgensen.

Enamel 2 piece dial. Clips onto the movement and locked by 2 laterally posed screws through the skirt.

Enamel detail. The black enamel details are added to the white enamel at a lower temperature to avoid the two colours running into each other.

The repeater hammers. Made in hardened steel

The oversized hour wheel. Larger in diameter than on the majority of movement constructions.

Balance and balance cock. The steel of the bi-metalic balance wheel

5 minute repeater mechanism. All levers, racks and springs made in hardened steel and hand finished.

The Swiss lever cock is made in hardened steel and mirror finished.

Centre 5 minute cam, that control the distance the 5 minute rack drops.

Lower hour rack, closest to the mainplate, the pinion above it is engaged by the operating lever

Escape wheel in place with the lever cock and balance removed

The double layered escape wheel. The lower section below the escape wheel controls the jumping strokes of the off set seconds which pulses 5 times during each second.

Stud holding the balance spring, the direction of the screws is irregular to the majoroty of watches with a similar system.

Repeater barrel arbour jewel. The jewel is rubbed into a gold chaton (bushing) and pushed into the German silver bridge then secured by 3 screws.

The heart shaped cam is fixed to the axe which holds the chronograph seconds hand

The return to zero hammer which is below the heart shaped cam is guided

This cam is the selection device for the chronograpgh

A gold end-piece for the escapewheel, limiting the vertical play and pivot friction, as with a balance wheel pivot.

A single safety roller, housing the impulse jewel made for hardened and polished steel

The Swiss lever with counter poise balance. The cut out in the circle allows the escape wheel axe to pass through during assembly

Sitting closer to the edge of the mainplate is a large steel piece which is adjusted to allow the distance between the hammer and the gong.

The hour rack sitting closest to the mainplate surface, below this on the other side of the

The centre wheel is below the cam and centre bridge, turning once per hour.

All the engraving is executed by hand.

The small snail on top of the hour rack drives the 5 minute rack here removed.

5 minute rack. The rack which trips the second hammer to sound the passing 5 minutes periods

The 5 minute jumper trip in the centre of the image is push by the 5 min rack to lift the hammer

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

masterclass courses