ABSTRACT
Making an instrument like the cyanometer helps to show the work that goes into constructing a numerical sensory vocabulary of blue, and of creating sensory standards or reference points more generally. The tool is made up of whatever comes to hand Prussian blue dye in de Saussure's case, or for the cyanometer the people will make in this lesson, commercially produced paint sample cards available at their nearest hardware store. Attending to the history of the colour shows that the sky has not always been blue either, something that is important to keep in mind when using the cyanometer the people have made. In a podcast called 'Why isn't the sky blue', the RadioLab team explore the historical situatedness of the link between skies and blueness. Doctors need to learn ways of looking for cyanosis, to learn to make the connections between the word and the sign of illness in the body.
