Henry Sully was an English clockmaker

Clockmaker

A clockmaker is an artisan who makes and repairs clocks. Since almost all clocks are now factory-made, most modern clockmakers only repair clocks. Modern clockmakers may be employed by jewellers, antique shops, and places devoted strictly to repairing clocks and watches...

. He lived for many years in France.

Marine clock

He invented a marine clock

Marine chronometer

A marine chronometer is a clock that is precise and accurate enough to be used as a portable time standard; it can therefore be used to determine longitude by means of celestial navigation...

 to determine longitude

Longitude

Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

 accurately, a sophisticated pendulum clock

Pendulum clock

A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is a resonant device; it swings back and forth in a precise time interval dependent on its length, and resists swinging at other rates...

. He presented a first Montre de la Mer in 1716 to the French Académie des Sciences. He was the first to develop chronometer in Paris. In 1718, Henry Sully established a watch factory in Versailles

Versailles

Versailles , a city renowned for its château, the Palace of Versailles, was the de facto capital of the kingdom of France for over a century, from 1682 to 1789. It is now a wealthy suburb of Paris and remains an important administrative and judicial centre...

. He presented two new models in 1723. In 1726, he published Une Horloge inventée et executée par M. Sulli. His chronometers performed well in calm weather, but not on the high seas.

Henry Sully worked with Julien Le Roy

Julien Le Roy

Julien Le Roy was a major 18th-century Parisian clockmaker and watchmaker.He was born in Tours in 1686, and by the age of 13, had already made his first clock. In 1699, he moved to Paris for further training. He became maitre horloger in 1713 and later juré of his guild...

, a clockmaker to Louis XV. In France, Henry Sully was followed in his developments by Pierre le Roy

Pierre Le Roy

Pierre Le Roy was a French clockmaker. He was the inventor of the detent escapement, the temperature-compensated balance and the isochronous balance spring. His developments are considered as the foundation of the modern chronometer...

 and Ferdinand Berthoud

Ferdinand Berthoud

Ferdinand Berthoud was a Swiss chronometer-maker.-Career:He was born at Plancemont, Neuchâtel, Switzerland. Having served his apprenticeship with his brother, Jean-Henri, a pendulum maker, he set up a clockmaking business in Paris in 1745 and gained a great reputation for the excellence and...

.

Soon after the 1726 publication of Une Horloge inventée et executée par M. Sulli, John Harrison

John Harrison

John Harrison was a self-educated English clockmaker. He invented the marine chronometer, a long-sought device in solving the problem of establishing the East-West position or longitude of a ship at sea, thus revolutionising and extending the possibility of safe long distance sea travel in the Age...

 started developing his own famous chronometer, creating a description and drawings for a proposed marine clock in 1730 and actually manufacturing the Harrison H1 in 1735.

Gnomon of Saint-Sulpice

The priest of Église Saint-Sulpice, Paris, Languet de Gergy

Jean-Baptiste Languet de Gergy

Jean-Baptiste Languet de Gergy was parish priest at Eglise Saint-Sulpice in Paris from 1714 to 1748. He was the initiator of the construction of the Gnomon of Saint-Sulpice. Languet de Gergy initially wished to establish the exact astrological time in order to ring the bells at the most...

, wishing to establish the exact astrological time in order to ring the bells at the most appropriate time of day, commissioned Henry Sully to build the Gnomon of Saint-Sulpice

Gnomon of Saint-Sulpice

The Gnomon of Saint-Sulpice is an astronomical measurement device located in the Church of Saint-Sulpice in Paris, France. It is a gnomon, a device designed to cast a shadow on the ground in order to determine the position of the sun in the sky...

.

In 1737, another one of his books was published: Illustrations de Règle artificielle du temps, traité de la division naturelle et artificielle du temps....

External links

• Académie des Sciences 1726 report: Description of a clock of a new invention for the true measure of time at sea in New memoirs of literature by Michel de La Roche
  Michel de La Roche
  Michel de La Roche was a French Huguenot refugee and author in England, where he was known as an editor of early literary periodicals, monthly or quarterly.-Life:...
  
  , p.444 http://books.google.com/books?id=qA8wAAAAYAAJ&pg=PA444