Chegado ao mercado - Girard Perregaux ww.tc John Harrison

Girard-Perregaux ww.tc John Harrison. Edição limitada a 50 exemplares. Calibre automático da manufactura (GP033G0). Horas do mundo, com indicação de Dia / Noite. Caixa de 41 mm, em ouro branco, estanque até 50 metros.

Mostrador em esmalte decorado segundo a técnica champlevé. O desenho evoca a viagem feita de Novembro de 1761 a Março de 1762, entre Portsmouth, Inglaterra, Port Royal, Jamaica, e volta, por um navio onde o filho de John Harrison, William, transportava o cronómetro de marinha H-4, aquele que valeu o prémio da Coroa britânica àquele que resolveu o problema do achamento da Longitude no mar. Se, numa primeira viagem, em 1736, o H-1 fez uma viagem de Londres até Lisboa e volta, a viagem decisiva teve escala na Madeira (para saber mais, História do Tempo em Portugal, Diamantouro, 2003).

Da marca:

In October 1707, the English admiral Sir Cloudesley Shovell made an error when estimating the longitude of his squadron of warships. As a result, the squadron ran aground on the Scilly Isles off the south-west coast of England and was wrecked, causing the deaths of some 2,000 men including the admiral himself.

This disaster, which occurred when the expansion of the British Empire across the world’s seas represented a major political and economic issue at the time, led the government to rally the entire scientific community around a single common project: calculating longitude at sea. In 1714, the British Parliament passed the Longitude Act, offering a reward of 20,000 pounds (the equivalent of several million dollars today!) to anyone who could find a method of calculating a ship's longitude to within half a degree (approximately 30 km).

Leading scientific minds of the era studied the subject closely, as did the watchmaker John Harrison, whose approach promised the great advantage of simplicity. His idea was to use a clock to measure the time difference between the journey’s starting point and the ship's current position. Because the Earth completes one full revolution in approximately 24 hours, each hour thus represents 15 degrees of rotation, or 15 degrees’ difference in longitude. By measuring the difference between the exact local time at the ship's position (determined using a sextant) and the exact reference time (at the point of departure, indicated by the clock) the longitude of the ship can be calculated. The challenge was therefore to create a clock that would maintain its accuracy even when pitching and rolling on the world’s roughest seas.

Making this timepiece became John Harrison's eternal quest. This self-taught watchmaker, who was born on 24 March 1693 and had been trained as a carpenter, devoted his entire life to developing reliable and accurate timepieces. He built new types of mechanisms based on the work that Christian Huygens and Robert Hooke had carried out on the spiral spring, and used brass and steel alloys to reduce the effect of expansion and contraction.

In 1773, after many successes and failures, the spectacular performance of his H-4 watch was recognised and earned him part of the reward promised in the Longitude Act. The bitter rivalries surrounding the prize and the ambiguous conditions imposed to obtain it meant that the total amount was never awarded in full.

With its long history of continuous research into precision, the Girard-Perregaux Manufacture pays tribute to this remarkable 18th-century watchmaker by adding an exclusive creation to its ww.tc (world wide time control) collection

The dial of this exceptional timepiece depicts the journey undertaken by John Harrison's son William from Portsmouth, England, to Port Royal, Jamaica, against a map of the Atlantic Ocean. The trip lasted from November 1761 to March 1762 and was intended to test the reliability of the H-4 timepiece, which was much smaller than the first prototypes developed to calculate longitude. The H-1, for example, weighed 32.5 kg.

The dial of the ww.tc John Harrison offers a superb example of delicate champlevé enamel, produced in the enamelling workshop of the Girard-Perregaux Manufacture. The contours of the map are engraved on an unprocessed plate of white gold, while the compass rose, showing the eight directions of the wind and measuring no more than 3 mm, is hand-sculpted by a craftsman-engraver. The liquid green and blue enamel is laid into the cavities using a brush. Next comes the firing, timed to the minute in a furnace at 800°C, to create the magic of vitrification. After cooling, the excess enamel is removed by vigorous sanding using a hard stone and water. The dial is then manually polished with a diamond file, before a last firing called "Dorure" or gilding adds shine and reveals the enamel’s full splendour. William Harrison's journey is delicately indicated by a trace of silvered powder stretching from Europe to America.

Echoing the dial, Portsmouth and Port Royal are highlighted in royal blue on the cities ring, which is activated by the white-gold crown and delicately engraved with the GP logo at 9 o'clock. Universal time, as distinct from local time, can be instantly read off from the blue/white hours ring using the rhodium-plated leaf-shaped minutes hand.

The hands are also subtly skeletonised, adding exquisite elegance and discretion to their ballet around the enamelled dial. The alternation of satin-brushed and polished finishes on the white-gold case adds a sense of distinguished finesse to its beautifully balanced proportions.

The transparent case-back reveals the Girard-Perregaux 033G0 automatic calibre, which is widely recognised for the excellence and reliability of its construction. It is fitted with an ingenious coupling mechanism that activates the bicoloured ring indicating the time in 24 time zones. As an ultimate tribute to this fabulous journey in watchmaking history, the pink gold oscillating weight is engraved with a parchment bearing the dates on which the H-4 started and finished its Atlantic crossing.