Neuchâtel based Swiss watch manufacturer HERITAGE WATCH MANUFACTORY presents FIRMAMENTUM, a unique measurement and navigation instrument, which will be unveiled at Basel world 2012.

Fully in the tradition of timepieces used for observation, the FIRMAMENTUM, with Calibre No. 870, is an extraordinary timepiece designed for measurement and navigation.

As well as the classic method of measuring time, with the aid of the hour angle it permits measurement of the movement of the sun and planets in our solar system, as well as that of stars.

Developed the by master watchmaker Karsten Fraessdorf, the FIRMAMENTUM combines, in two displays, measurement of the hour angle based on our solar time with that based on the stars – the sidereal hour angle. Due to a unique mechanism with a variable-speed gear train, one of the displays has been designed to be variable, and can switch between solar and sidereal time by means of a pushbutton.

Accordingly, FIRMAMENTUM not only permits the simultaneous observation of two heavenly bodies within our solar system, but also the observing of the sun or a planet, or even a star outside the solar system. Moreover, in parallel, the hours minutes and sub-seconds can be read off just as on a normal watch. The fixed solar time display has in addition been conceived such that it can be additionally used as an adjustable second time zone with a 24-hour display accurate to the minute.

The FIRMAMENTUM also has an integrated function that, via a second pushbutton, synchronizes the time in accordance with a time signal. The power reserve indicator brings the underlying data of the watch to the fore. A stop lever halts operation of the watch movement after a running time of 56 hours.

This allows FIRMAMENTUM to not only provide exact navigation and determination of position for nautical and flying purposes, but also offers a much simplified basis for astronomy. Both requirements are aided by the unusually designed dial, which not only shows the usual methods of navigation but also permits the solar or sidereal hours and minutes used by astronomers to be read off.

With its restrained and discreet design, the dial of Firmamentum directly shows the different values in degrees according to the various navigation methods that are possible with this watch. Anchored in the traditions of navigation, these permit determination of position according to azimuth, the equatorial method and the ecliptic system.

The second method of measurement, the so-called equatorial method, is the measurement of latitude. The latitude corresponds to the circle upon which can be found the visible horizon of the observer, the true horizon. One speaks of a parallel of latitude when referring to a circle parallel to the Equator. When one approaches the North Pole or the South Pole ever more closely, the diameter of the parallel of latitude becomes smaller. It is split into 360 degrees. All meridians leading from the North Pole to the South Pole are equally long. The zero point is the line from the North to the South Pole that by definition passes through the Greenwich Observatory.

It is known as the Prime Meridian and all other meridians, including the one passing from North to South through the observer’s own location, are removed from this by up to + 180 degrees in a westerly direction and – 180 degrees in an easterly direction. In the equatorial method, the meridians are projected outwards from the centre of the Earth onto an imaginary heavenly circle and the first coordinate is provided by the degrees measured. In this method, the meridians are called declination or hour circles.

These lines start from the Equator and go up to +90 degrees in a northerly direction and up to – 90 degrees in a southerly direction as if they were marked on a globe. The spatial depth, i.e. the differing distances from the stars to the earth, does not play a role here. The second coordinate is given by the Equator with its 360-degree divisions. This coordinate is known as right ascension and is given from the North to the West, South and East from 0 degrees to 360 degrees.

The third system that of the ecliptic, has the same coordinate system as the second system, the equatorial. However both coordinate axes are shifted by the value of the ecliptic. The ecliptic is the difference (the angle) between the orbit of the Earth around the Sun and the Sun’s equator. The right ascension then gives the longitude, the declination the latitude.

Hour Angle
Every hour angle, independently of its frame of reference and numerical system, consists of a 360-degree circle. Each degree is divided into 60 units, the so-called arc minutes. These arc minutes are identified by a single quote (60′) and in their turn these are subdivided into 60 arc seconds (60″). These units can however vary, for example in nautical systems. 360 degrees times 60’gives 21 600′, and this result is taken to divide the circumference of the Earth at the Equator. This gives a value of 1 852 metres per arc minute. A nautical sea mile is therefore 1/21 600th of the Earth’s circumference at the Equator. This sea mile is subdivided into 10 cable lengths, each of 185 metres. This means that when a ship on the Equator has travelled one sea mile, it has also travelled one arc minute (1′).

Difference between Solar and Sidereal Time
Due to the rotation of the Earth on its own axis and the same direction of rotation around the sun, this gives the effect that within our solar system a year consists of 365 sun- and planet-rises.

However outside our solar system, 366 sun- and planet-rises are measured in the same period. The system of time that splits the year into 365 days is thus called solar time, and that which splits a year into 366 days is known as the sidereal time. This results in a daily difference of approximately 4 minutes between both time systems. Accordingly, the length of one sidereal day is 23 hours, 56 minutes and4.0905 seconds. The special Firmamentum gear train that measures the difference between solar and sidereal time is so precise that the difference per day is only 0.0005 seconds.

Methods of Determining Position
There are different ways of measuring one’s position on the Earth’s surface. The first, and the most natural way of observing this, is that of the azimuth. The basis for this is given by the location of the observer. He observes the horizon and, with the help of a device that measures degrees — a sextant — he determines the height of a heavenly body above the horizon as he sees it in front of him. When determining terrestrial locations, things that stand out in the landscape or buildings can be used as the starting point. This gives the first coordinate. For the North direction it is given from 0 to + 90 degrees, and from the South direction from 0 to – 90 degrees.

Technical details
Hour angle instrument for the observation of heavenly bodies by means of 13 hands with two additional displays
Hour angle variable for sidereal and solar time, arcdegrees, arcminutes, 5 / 100 arcseconds
Solar time hour angle display in arcdegrees, arcminutes, 5/100 arcseconds
Power reserve display with balance wheel stop mechanism
Status display for basic regulation of Vivax balance wheel
Display of solar time as astronomical time
Second time zone settable to one minute of accuracy
Time in solar or sidereal time
Status of sidereal or solar time with variable hour angle, synchronisation mode

Independent manufacture Calibre: Cal. 870
3 patents pending
Diameter: 38.90 mm
Thickness: 7.50 mm
No of parts: 483
Jewels: 92
Escapement: Swiss lever escapement; capillary phase to improve oil retention
Balance: Mass-regulated Vivax balance / 16 mm / patent pending
Balance spring: Over-coil hairspring (Breguet)
Fine regulation: Tenere fine adjustment / patent pending
Semi oscillations: 18 000 / h
Mainspring barrel diameter: 17.40 mm
Moment of inertia: 110 mgcm²

Gear train
Gear tooth system: Cycloid gear teeth
Pinions: Fully hardened steel pinions
Gears: Copper beryllium
Mainspring barrel: Copper beryllium
Screws: Steel, blued and polished
Power reserve: 56 h

Movement plates: Hand bevelled

Designed by: Eric Giroud
Material: Polished / satinised steel
Water resistance: 50 m
Diameter: 44.50 mm
Thickness: 15.35 mm (with out crystal: 11.60 mm)
Crystal: Domed sapphire glass
Caseback: Flat sapphire glass

Designed by Eric Giroud
Dial positioned by means of pins, screwed directly onto the movement
German silver plate and white gold applications
Hands: Hardened steel

Leather / alligator, with pin buckle
Strap-holding bridge:  24 mm / buckle:  20 mm

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