Friday, 11 July 2008

Blue sky research with a cyanometer

Science and art have a long history of crossovers: botanical illustrations, anatomy drawings… Observation is key to both scientists and artists. Accurate depiction of the observed reality moves science forward. Artists can better paint or draw what they understand. It is easy to forego what is in front of you if you don’t “know” it is there.

Artists can develop this ability to “see”. They also have a creative mind. The combination of the two leads to breakthrough intuitions. Some artists painted what they observed so well that scientists relied on their paintings to describe certain physiological conditions.

The cyanometer

The cyanometer is a device invented by the Swiss scientist Horace Bénédict de Saussure to measure the blueness of the sky. The picture will give you a better idea than a long description.

De Saussure’s name is linked to the birth of mountaineering. In 1760, he offered a reward for whoever would climb on the top of the Mont-Blanc. This feat was accomplished in 1786 by two climbers: Jacques Balmat and Gabriel Pascard. A year later, on August 3rd 1787, de Saussure himself went on top of the mountain with his butler and eighteen guides. He needed that many people to carry all the devices he wanted for his scientific experiments. One of the devices was a cyanometer.

De Saussure hoped that the information collected on the blueness of the sky could be used for weather forecasts. The cyanometer proved of little use for this task. It could however be useful to the painter.

The artist and the cyanometer

A cyanometer provides an easy way to study the sky and find out about the different hues of blue that compose it. The windows in the divice play the role of isolators. You can observe the exact hue because the blue you observe is mostly framed with a neutral colour, removing the interference of simultaneous contrasts.

There are many paths to explore:
  • Where is the sky of a lighter blue?

  • Is the sky lighter or darker towards the horizon?

  • How many kind of blue can you find in the sky?

  • How the morning sky compares to the afternoon one?
If you use the cyanometer in conjunction with a reference chart (where you noted how you mixed the different shades of blue), the cyanometer will help you to determine how to mix your blue colours to paint the sky.

You could even use the cyanometer in the same way to judge the different shades of blue on your reference photographs.

I will soon explain the way to build a simple cyanometer.

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