Timezone Features July 9, 2013 Timezone Feature
Up Close With the Geo.Graham Tourbillon Orrery
Eric Loth, Founder of GRAHAM SA
Eric Loth, Founder of GRAHAM SA, presents TimeZone with the masterpiece he dreamt of building since he founded the company.
In 1713, under the patronage of Charles Boyle, 4th Earl of Orrery, English watch and clockmaker George Graham invented a mechanical device driven by a clockwork that demonstrates the relative positions and motions of planets and moons in the solar system. The device was named the “Orrery” in the Earl’s honour.
For 2013, GRAHAM celebrates the 300th anniversary of the Orrery with its three dimensional Geo.Graham Tourbillon Orrery, a central tourbillon with astronomical complication.
Geo.Graham Tourbillon Orrery, Ref. 2GGBP.B01A
Original Orrery by George Graham
© Museum of the History of Science, Oxford
The Tourbillon Orrery includes the Moon, Earth, Mars and the Sun based on a 300-year calendar. The Moon is represented by a rhodium sphere that orbits the Earth. The Earth is represented by a blue sapphire sphere that orbits the Sun. Mars is represented by a round ruby and circles the Sun on the outer edge of the dial. At the center of the dial, the Sun is represented by a hand-engraved Tourbillon bridge inspired by an original movement by George Graham.
The Earth orbits at exactly 365 ¼ days so there is no adjustment for the leap year. Corrections to the orbital patterns are minimal and are indicated by the 100-year counter engraved into the sapphire crystal display back. The Moon is corrected once every 7 years, Mars once every 25 years and the Earth once every 1,156 years. The Moon and Mars have push-correctors integrated into the case. Altogether, the Orrery should be functional for 300 years before needing to be serviced by a watchmaker for a minor adjustment to the perpetual calendar.
The 18-carat pink gold case measures 48mm x 17.60mm. The black dial is organised in three scales. From the outside to the center of the dial are: the hours and minutes scale, the Gregorian calendar in Latin (365.25 days), and the Zodiac scale with 12 astrological signs in Latin.
The 35-jewel, Calibre G1800 is a high precision mechanical movement made exclusively for GRAHAM by Christophe Claret with fine finishing. It features twin barrels and a 72-hour power reserve.
The George Graham movement that inspired the hand-engraved Geo.Graham
© The Royal Society
Hand-engraved Tourbillon bridge with diamond end stone
The Earth (blue sapphire sphere) indicates the date and Zodiac written in Latin.
The crown at 2 o’clock is a quickset date adjustable forwards/backwards (one crown turn = 10 days)
Off-centre 18-carat pink gold hands with black Super-LumiNova coating
Moon corrector at 4 o’clock
Mars corrector at 10 o’clock
The Calibre G1800 is an exclusive collaboration with the Christophe Claret Manufacture
The year counter indicates corrections for the Moon (7 years), Mars (25 years) and Earth (1,156 years)