Gabriel Mouton
Encyclopedia
Gabriel Mouton was a French
abbot and scientist. He was a doctor of theology from Lyon
, but was also interested in mathematics and astronomy.
His 1670 book, the Observationes diametrorum solis et lunae apparentium, came to form the basis of what was to become the metric system
hundred years later. Based on the measurements of the size of the Earth
conducted by Riccioli
of Bologna (at 321,815 Bologna feet to the degree), Mouton proposed a decimal
system of measurement based on the circumference of the Earth, explaining the advantages of a system based on nature. Mouton's publication appeared two years after John Wilkins
, then president of the Royal Society
published a similar proposal.
His suggestion was a unit, milliare, that was defined as a minute of arc
along a meridian arc
, and a system of sub-units, dividing successively by factors of ten into the centuria, decuria, virga, virgula, decima, centesima, and millesima. The virga, 1/1000 of a minute of arc, corresponding to 64.4 Bologna inches, or ~2.04 m, was reasonably close to then current unit of length, the Parisian toise (~1.95 m) – a feature which was meant to make acceptance of the new unit easier.
As a practical implementation, Mouton suggested that the actual standard be based on pendulum
movement, so that a pendulum located in Lyon of length one virgula (1/10 virga) would change direction 3959.2 times in half an hour. The resulting pendulum would have a length of ~20.54 cm. Wilkins however proposed using a pendulum that was 0.994 m in length.
His ideas attracted interest at the time, and were supported by Jean Picard
as well as Huygens in 1673, and also studied at Royal Society
in London
. In 1673, Leibniz independently made proposals similar to those of Mouton.
It would be over a century later, however, that the French Academy of Sciences
weights and measures committee suggested the decimal metric system
that defined the Metre as, at least initially, a division of the circumference of the Earth. The first official adoption of this system occurred in France in 1791.
By today's measures, his milliare corresponds directly to a nautical mile, and his virga would by definition have been 1.852 m.
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
abbot and scientist. He was a doctor of theology from Lyon
Lyon
Lyon , is a city in east-central France in the Rhône-Alpes region, situated between Paris and Marseille. Lyon is located at from Paris, from Marseille, from Geneva, from Turin, and from Barcelona. The residents of the city are called Lyonnais....
, but was also interested in mathematics and astronomy.
His 1670 book, the Observationes diametrorum solis et lunae apparentium, came to form the basis of what was to become the metric system
Metric system
The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...
hundred years later. Based on the measurements of the size of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
conducted by Riccioli
Giovanni Battista Riccioli
Giovanni Battista Riccioli was an Italian astronomer and a Catholic priest in the Jesuit order...
of Bologna (at 321,815 Bologna feet to the degree), Mouton proposed a decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....
system of measurement based on the circumference of the Earth, explaining the advantages of a system based on nature. Mouton's publication appeared two years after John Wilkins
John Wilkins
John Wilkins FRS was an English clergyman, natural philosopher and author, as well as a founder of the Invisible College and one of the founders of the Royal Society, and Bishop of Chester from 1668 until his death....
, then president of the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
published a similar proposal.
His suggestion was a unit, milliare, that was defined as a minute of arc
Minute of arc
A minute of arc, arcminute, or minute of angle , is a unit of angular measurement equal to one sixtieth of one degree. In turn, a second of arc or arcsecond is one sixtieth of one minute of arc....
along a meridian arc
Meridian arc
In geodesy, a meridian arc measurement is a highly accurate determination of the distance between two points with the same longitude. Two or more such determinations at different locations then specify the shape of the reference ellipsoid which best approximates the shape of the geoid. This...
, and a system of sub-units, dividing successively by factors of ten into the centuria, decuria, virga, virgula, decima, centesima, and millesima. The virga, 1/1000 of a minute of arc, corresponding to 64.4 Bologna inches, or ~2.04 m, was reasonably close to then current unit of length, the Parisian toise (~1.95 m) – a feature which was meant to make acceptance of the new unit easier.
As a practical implementation, Mouton suggested that the actual standard be based on pendulum
Pendulum
A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position...
movement, so that a pendulum located in Lyon of length one virgula (1/10 virga) would change direction 3959.2 times in half an hour. The resulting pendulum would have a length of ~20.54 cm. Wilkins however proposed using a pendulum that was 0.994 m in length.
His ideas attracted interest at the time, and were supported by Jean Picard
Jean Picard
Jean-Felix Picard was a French astronomer and priest born in La Flèche, where he studied at the Jesuit Collège Royal Henry-Le-Grand. He was the first person to measure the size of the Earth to a reasonable degree of accuracy in a survey conducted in 1669–70, for which he is honored with a...
as well as Huygens in 1673, and also studied at Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
. In 1673, Leibniz independently made proposals similar to those of Mouton.
It would be over a century later, however, that the French Academy of Sciences
French Academy of Sciences
The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...
weights and measures committee suggested the decimal metric system
Metric system
The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...
that defined the Metre as, at least initially, a division of the circumference of the Earth. The first official adoption of this system occurred in France in 1791.
By today's measures, his milliare corresponds directly to a nautical mile, and his virga would by definition have been 1.852 m.