Or here:
http://www.preussen-chronik.de/bild_...=bild_215.html
Called: Der König überall (The king everywhere)
Paintings by Robert Warthmüller - 1886
In the painting, the legend of the "ubiquitous King" follows King Frederick II examines the potatoes . His attempt in 1750 to introduce the potato as an alternative to food crops failed, initially at the lack of knowledge of farmers about the cultivation and their distrust. A year later, the state-controlled trial was already successful. 1785, shortly before the death of the king, there were already many potato fields with good yields.
Much larger version of painting
here.