A fascinating early woodblock showing the concept of a "handsonnenuhr" or "hand sundial," a primitive way of telling time. This depiction first appeared in the very scarce early German astronomical text Des Himmels Lauffes Wirckung und Naturliche Influentz der Planeten. . ., published at Christian Egenolffs's printing studio in Frankfurt.
The principle of a hand sundial is you can estimate the time of day by holding a small stick in your hand (left in the morning and right in the afternoon) and facing away from the sun. Then, you see where the shadow of the stick falls in your hand, and using a diagram such as the present, you can then estimate the time of day.
The text around the woodblock is a gnomic poem, which helps the reader to remember how to operate one of these. The rest of Des Himmels. . . included numerous other woodblock prints showing the tools and mythologies surrounding the study of the stars.