Fabrizio Mordente (Salerno, 1532 – ca 1608) was an Italian mathematician. He is best known for his invention of the " proportional eight-pointed compass" which has two arms with cursors that allow the solution of problems in measuring the circumference, area and angles of a circle. In 1567 he published a single sheet treatise in Venice showing illustrations of his device.

Life and career

Fabrizio Mordente was born in Salerno, Italy, and studied at the Università di Napoli. After completing his studies at the age of 20, he set out to see the world. He left Naples in 1552 and visited Crete, Cyprus, Egypt, Palestine and Mesopotamia. After reaching the

Persian Gulf The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Persis, Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a Mediterranean sea (oceanography), me ...

, he took a Portuguese ship to India. He stayed in

Goa Goa () is a state on the southwestern coast of India within the Konkan region, geographically separated from the Deccan highlands by the Western Ghats. It is located between the Indian states of Maharashtra to the north and Karnataka to the ...

for three years and then continued his voyage around the

Cape of Good Hope The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is t ...

, eventually arriving in Lisbon. He went from there to Paris and visited other European cities before returning to Italy and visiting Venice, Florence and Rome. During this trip he drafted the initial design for his compass. Based on the success of his design, Mordente took service in 1571 at the court of

Emperor Maximilian II Maximilian II (31 July 1527 – 12 October 1576) was Holy Roman Emperor from 1564 until his death in 1576. A member of the Austrian House of Habsburg, he was crowned King of Bohemia in Prague on 14 May 1562 and elected King of Germany (King ...

in Vienna. From 1578 he served in

Prague Prague ( ; cs, Praha ; german: Prag, ; la, Praga) is the capital and largest city in the Czech Republic, and the historical capital of Bohemia. On the Vltava river, Prague is home to about 1.3 million people. The city has a temperate ...

at the court of

Rudolph II Rudolf II (18 July 1552 – 20 January 1612) was Holy Roman Emperor (1576–1612), King of Hungary and Croatia (as Rudolf I, 1572–1608), King of Bohemia (1575–1608/1611) and Archduke of Austria (1576–1608). He was a member of the Hous ...

, to whom he dedicated an edition of ''Anversa'' in 1584. In Prague, he also met

Michiel Coignet Michiel Coignet (also Quignet, Cognet or Connette in Italian) (1549 in Antwerp – 24 December 1623 in Antwerp) was a Flemish polymath who made significant contributions to various disciplines including cosmography, mathematics, navigation and car ...

and

Giordano Bruno Giordano Bruno (; ; la, Iordanus Brunus Nolanus; born Filippo Bruno, January or February 1548 – 17 February 1600) was an Italian philosopher, mathematician, poet, cosmological theorist, and Hermetic occultist. He is known for his cosmologic ...

, who used the compass to refute

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...

's hypothesis on the incommensurability of infinitesimals, thus confirming the existence of the "minimum" which was the basis of his atomic theory. Bruno published the dialogues ''Mordentius'' and ''De Mordentii circino'' which praised Mordente, but also presented criticisms that raised protests from the mathematician. Mordente replied in 1586 and Bruno responded with the satires ''Idiota triumphans'' and ''De somnii interpretatione.'' After Mordente gained support in the dispute from the French

Charles, Duke of Guise Charles de Lorraine, 4th Duke of Guise and 3rd Prince of Joinville (20 August 1571 – 30 September 1640), was the son of Henry I, Duke of Guise and Catherine of Cleves, and succeeded his father as Duke of Guise in 1588. Initially part of the Cath ...

, Bruno was forced to flee Paris. After this controversy, Mordente took service with the Duke of Guise until his death. In 1591 Mordente returned to Italy and entered the service of

Alexander Farnese, Duke of Parma Alexander Farnese ( it, Alessandro Farnese, es, Alejandro Farnesio; 27 August 1545 – 3 December 1592) was an Italian noble and condottiero and later a general of the Spanish army, who was Duke of Parma, Piacenza and Castro from 1586 to 1592 ...

, where he published his last mathematical treatise.

Publication

Mordente published a number of treatises on mathematics and the use of his compass. These include: *''Modo di trovare con l’astrolabio, o quadrante, o altro instromento, oltre gradi, intieri, i minuti, et secondi, et ognaltra particella'', Venezia 1567 *''Il compasso del s. Fabritio Mordente con altri istromenti mathematici ritrovati da Gasparo suo fratello'', Anversa, Ch. Plantino, 1584 *''Il compasso e figura di Fabritio Mordente...'', Parigi, J. Le Clerc, 1585 Milano, Biblioteca Ambrosiana, D 235 inf., Problema mirabile di Fabritio Mordente (1586 circa), ms., cc. 107, 239; Q. 122. sup., c. 106r *''La quadratura del cerchio, la scienza de’ residui, il compasso et riga di Fabritio, et di Gasparo Mordente fratelli salernitani'', Anversa, Ph. Galle, 1591 (Roma, Biblioteca nazionale, copia manoscritta, Gesuitico, 615) *''Le propositioni di Fabritio Mordente salernitano…'', Roma, A. Giamin, 1598

References

{{DEFAULTSORT:Mordente, Fabrizio 1532 births 1608 deaths 16th-century Italian mathematicians 16th-century Italian philosophers