héliostat

Forms

héliostat m (plural héliostats)^[1]

Etymology

It is borrowed from New Latin heliostata, the scientific Latin term used by the Dutch physicist Willem Jacob 's Gravesande in his Latin treatise on physics of 1720–21.^[2] The Latin word is compounded of Ancient Greek ἥλιος (hḗlios, “sun”) and στατός (statós, “standing, stationary”).^[2][3] The Grand Robert, the Petit Robert and Wiktionary analyse it within French as hélio- with -stat;^[4][5][1] the GLLF traces the second element to the Greek verb ἵστημι (hístēmi, “to make stand, fix”).^[3] Littré gives the same analysis, glossing the Greek adjective as “stopped”.^[6]

Earliest recorded meaning

It is first recorded in 1746, as heliostate, in Élie de Joncourt's French translation of 's Gravesande's elements of physics, glossed as a machine for fixing the rays of the sun.^[2][3]

Semantic evolution

The word has kept its technical sense: an optical instrument with a plane mirror driven by clockwork, which reflects the sun's rays onto a fixed point despite the sun's apparent motion.^[5][4] Littré describes it as an apparatus that keeps a ray let into a darkened room in a constant direction.^[6] The Grand Robert names the instruments of Foucault and Silbermann, and sets it beside the related cœlostat and sidérostat.^[4] Modern dictionaries also describe it as a single-mirror coelostat that sends sunlight in a chosen direction.^[7]

Timeline

• 1720–21 – 's Gravesande uses Latin heliostata in his Physices elementa mathematica.^[2]
• 1746 – Heliostate appears in Joncourt's French translation of the same work.^[2][4]
• 1873 – Littré records héliostat as an optical apparatus driven by clockwork.^[6]

Meanings

Noun

1. (physics) A heliostat: an optical instrument whose plane mirror, moved by clockwork, keeps reflecting the sun's rays onto a fixed point despite the sun's apparent motion.^[5][4][8]
2. A one-mirror cœlostat used to send sunlight in a given direction.^[7]

Word family

• héliostatique

Related words

• hélio-
• -stat
• cœlostat
• sidérostat
• héliographe
• Ancient Greek ἥλιος (hḗlios)

References

1. ^ a b c Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e Trésor de la langue française informatisé (2004), ATILF – CNRS & Université de Lorraine, atilf.fr/tlfi; electronic version of Imbs, Paul; Quemada, Bernard, eds. (1971–1994), Trésor de la langue française, Paris: CNRS / Gallimard
3. ^ a b c Guilbert, Louis; Lagane, René; Niobey, Georges, eds. (1971–1978; 1989), Grand Larousse de la langue française, Paris: Larousse
4. ^ a b c d e Rey, Alain, ed. (2005), Le Grand Robert de la langue française, electronic version, Paris: Le Robert
5. ^ a b c Rey-Debove, Josette; Rey, Alain, eds. (2007), Le Petit Robert de la langue française, Paris: Le Robert
6. ^ a b c Littré, Émile (1873–1877), Dictionnaire de la langue française, 4 vols. and supplement, Paris: Hachette
7. ^ a b Dictionnaire de français Larousse, larousse.fr/dictionnaires/francais (accessed 2024)
8. ^ Dictionnaire Le Robert en ligne, dictionnaire.lerobert.com (accessed 2024)