A colour-printed stipple portrait of Leonhard Euler

An oval portrait of the Swiss mathematician Leonhard Euler (1707-83), whose prolific output has been celebrated in his home country, Russia (where he supervised the creation of the 'Atlas Russicus', published 1745) and Germany (where he published the 'Atlas Geographicus' in 1753). The portrait shows his right eye shut, blinded after a near-fatal fever in 1735; by 1766 a cataract rendered his left eye almost useless. However his productivity hardly diminished: in 1775 he was still writing an average of one mahermatical paper a week.