Gabriel Mouton (1618 – 28 September 1694) was a French

abbot Abbot is an ecclesiastical title given to the male head of a monastery in various Western religious traditions, including Christianity. The office may also be given as an honorary title to a clergyman who is not the head of a monastery. Th ...

and

scientist A scientist is a person who conducts scientific research to advance knowledge in an area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosop ...

. He was a doctor of theology from

Lyon Lyon,, ; Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the third-largest city and second-largest metropolitan area of France. It is located at the confluence of the rivers Rhône and Saône, to the northwest of ...

, but was also interested in

mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

and

astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...

. His 1670 book, the ''Observationes diametrorum solis et lunae apparentium'', proposed a natural standard of length based on the circumference of the Earth, divided decimally. It was influential in the adoption of the

metric system The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the Intern ...

in 1799.

The milliare

Based on the measurements of the size of the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

conducted by

Riccioli Giovanni Battista Riccioli, SJ (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with falling bodies, for his discussion ...

of Bologna (at 321,815 Bologna feet to the degree), Mouton proposed a

decimal The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...

system of measurement based on the circumference of the Earth, explaining the advantages of a system based on nature. His suggestion was a unit, the ''milliare'', that was defined as a

minute of arc A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...

along a

meridian arc In geodesy and navigation, a meridian arc is the curve between two points on the Earth's surface having the same longitude. The term may refer either to a segment of the meridian, or to its length. The purpose of measuring meridian arcs is to ...

, 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 the 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 A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward th ...

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. His ideas attracted interest at the time, and were supported by

Jean Picard Jean Picard (21 July 1620 – 12 July 1682) was a French astronomer and priest born in La Flèche, where he studied at the Jesuit Collège Royal Henry-Le-Grand. He is principally notable for his accurate measure of the size of the Earth, bas ...

as well as Huygens in 1673, and also studied at

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...

. In 1673,

Leibniz Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of ma ...

independently made proposals similar to those of Mouton. It would be over a century later, however, that the

French Academy of Sciences The French Academy of Sciences (French: ''Académie des 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. It was at ...

weights and measures committee suggested the decimal

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.

Notes

References

* G. Bigourdan
''Le systeme metrique des poids et mesures''
1901, chapter ''Les precurseurs de la reforme des poids et mesures'' *

Ferdinand Hoefer Jean Chrétien Ferdinand Hoefer (German: ''Ferdinand Höfer'', 21 April 1811, Döschnitz – 4 May 1878) was a German-French physician and lexicographer. He is now known for his many works on the history of science. Selected works *''Élément ...

: ''Historie de l'astronomie'', Paris 1873

External links

Metrication - Genesis
*

{{DEFAULTSORT:Mouton, Gabriel 1618 births 1694 deaths 17th-century French mathematicians French Roman Catholics Catholic clergy scientists

The milliare

See also

Notes

References

External links