Small Marine Chronometer, Wittnauer 1940’s, Switzerland
Due to the absence of modern GPS systems and reliable long-range radio, sea voyages were unsafe without an accurate time meter. In order to navigate nautical charts, one needed to know the exact coordinates of the vessel, latitude and longitude. Finding the latitude is fairly simple – it can be determined by the angle of the position of the North Star in relation to the horizon, but determining the longitude is a bit more complicated.
For every hour, the earth rotates 15 degrees relative to the sun (by 24 hours it will have made a full 360-degree rotation). To find out the longitudinal angle, one needs to have the readings from two clocks – a sundial, and a reference chronometer set to Greenwich time. The coordinate is then calculated based on the difference between the readings, so for every four minutes that Greenwich time differed from the local time observed on board via the sundial, the ship had travelled on longitudinal degree.
Of course, the more accurate the ship’s reference chronometer, the more accurate the determination of the ship’s position on the chart. Therefore, before sailing, all ship’s chronometers were synchronised with the Greenwich time according to the observatory’s standard reference time.
The creation of ship’s chronometers has made a huge contribution to the history of the development of mechanisms for accurate time measurement. In the 16th – 19th centuries, high-profile competitions between watchmakers occurred, for who could make the most accurate chronometer. A victory in such a competition was considered highly honourable, and the winner was permitted to put the special symbol of an anchor on his watches. Among the winners of such competitions are the now legendary names of P. Leroy, A. L. Breguet, and Ulysse Nardin.
Marine chronometer, 1 MCHZ “Flight”, 1960s.
A typical ship’s marine chronometer is a very large watch in a doubled-up wooden case, in which a mechanism is suspended on a gimbal to maintain the horizontal position of the watch when the ship is pitching. The total weight of the device is about 10kg. The marine chronometer has hour, minute, and second hands, and a power reserve indicator. The mechanism usually has a spring detent escapement and a fusee with a chain to balance the spring force.
The main deck chronometer is a heavy a complex device. In addition to the main chronometer, there must be a spare on board for checking the time. A chronometer like this from the Swiss Wittnauer company is presented in the collection.
This chronometer has several interesting features that distinguish it from many other watches.
About the mechanism: this is the caliber 24.41 of the famous Swiss company Longines, a very high-precision movement with a fine finish. The case, dial, and hands are all made at the Longines factory. The importance of this device to the USA was realised through the American-Swiss company, Wittnauer.
The name of ‘Longines’ is covered with gilded strip, just above the work “Adjusted” on the movement – it has been removed by milling. Alledgedly, the decision to the hide the name is related to the customs and export issues of the 1930’s.
The movement serial number corresponds to production in 1932.
The power reserve indicator is the most interesting device in this watch. In recent years, this complication of the mechanism has come back into fashion and has become common in wristwatches. However, in the past only special timekeeping devices were supplied with the factory indicator, for which regular, long-term maintenance was critical. Here, the power reserve indicator uses a hand to show the number of hours that have lapsed since the last full winding. The sector scale is graded from 0 (maximum winding) to 192 (minimum winding) hours.
Powerful mainspring for 8 days. The reinforced spring required the use of atypical gear ratios in the wheels.
Precision stroke regulator. The polished sun-shaped stroke regulator with a cam allows for particularly precise adjustments of the travel deviation. Due to this regulator and screws on the rim of the balance, the mechanism has just three adjustments – for isochronism when the temperature changes, and at two positions (with the dial up and the crown down). For a watch installed in the dashboard, three adjustments are the actually the maximum available, because it is not worn on the wrist.
Start-stop. It seems that this device was not provided by the standard Longines 24.41 caliber, and instead was produced by the Wittnauer company while it was being assembled in the case. The start-stop lever has been designed very simply and is displayed on the back of the case. A curved wire is attached to the lever, which tangentially comes into contact with the balance wheel, either stopping the balance or causing it to move slightly enough to start immediately.
In general, this is a very interesting and rare instance of a watch with a complex high-end mechanism in good collectible condition.
Details of the Wittnauer Small Marine Chronometer, Swiss-made, 1940’s:
- Lever escapement, split bimetallic balance with adjusting screws, isochronous Breguet spiral
- Longines caliber 24.41 (17 ruby jewels, 1920, diameter 52.80, height 12 mm)
- Movement serial number: 5113571 which corresponds to 1932
- Sun-shaped precision regulator
- Mainspring that runs for 8 days
- 24-hour scale
- Dial indicator for power reserve
- Lever for stop-start mechanism
- The mechanism can be adjusted in two positions for maintaining accuracy when the temperature changes
- Mechanism finishing: rhodium plating, Geneva stripes, circular graining
- Metal dial with two-tone painted numerals, blue steel hands
- Technological steel case for the instrument panel, plastic glass
- The serial numbers on the body, case, and mechanism are all the same
The Wittnauer company was founded by brothers Albert and Louis Wittnauer in 1880, and initially focused on the supply of Swiss watchmakers to the American market. The company is still a popular option on the American market.