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Horace-Bénédict de Saussure's cyanometer, 1760

A cyanometer (from cyan and -meter) is an instrument for measuring 'blueness', specifically the colour intensity of blue sky. It is attributed to Horace-Bénédict de Saussure and Alexander von Humboldt. It consists of squares of paper dyed in graduated shades of blue and arranged in a color circle or square that can be held up and compared to the color of the sky.

De Saussure is credited with inventing the cyanometer in 1789.[1] De Saussure's cyanometer had 53 sections, ranging from white to varying shades of blue (dyed with Prussian blue) and then to black,[2] arranged in a circle; he used the device to measure the color of the sky at Geneva, Chamonix, and Mont Blanc.[3] De Saussure concluded, correctly, that the color of the sky was dependent on the amount of suspended particles in the atmosphere.

Humboldt was also an eager user of the cyanometer on his voyages and explorations in South America.[4]

The blueness of the atmosphere indicates transparency and the amount of water vapour.

See also


  1. ^ H-B de Saussure, Description d'un cyanomètre ou d'un appareil destiné à mesurer la transparence de l'air, Mem. Acad. Roy. Turin, 1788-89, 4, 409
  2. ^ Saussure's cyanometer, from the Royal Society of Chemistry.
  3. ^ Pedro Lilienfeld, "A Blue Sky History." (2004). Optics and Photonics News. Vol. 15, Issue 6, pp. 32-39. doi:10.1364/OPN.15.6.000032
  4. ^ Götz Hoeppe (2007). Why the sky is blue: discovering the color of life. Princeton, New Jersey: Princeton University. p. 110. ISBN 978-0-691-12453-7.


  • Heubner (1840). "Über das Cyanometer". Zeitschrift für Physik und verwandte Wissenschaften. 6: 201.
  • Hermann von Schlagintweit, Adolf Schlagintweit (1850). Untersuchungen über die physicalische Geographie der Alpen in ihren Beziehungen zu den Phaenomenen der Gletscher, zur Geologie, Meteorologie und PflanzengeographieBarth. p. 441.
  • Lord Byron alludes to this device in his satirical verse epic Don Juan (Canto IV, 112 ) as an ironical means of measuring the blue of bluestocking ladies.

External links

  • Saussure's cyanometer, from the Royal Society of Chemistry. Accessed Nov. 19, 2010. Includes a picture of the cyanometer.
  • The Cyanometer Is a 225-Year-Old Tool for Measuring the Blueness of the Sky, by Christopher Jobson. May 9, 2014.

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