The Renaissance scholar and printer Christophe Plantin adopted a pair of compasses as his printer's mark. This mark appeared in multiple different forms over the years on the title pages of the books he published through the Plantin Press. His Latin motto, Labore et Constantia (`By Labour and Constancy') is associated with an image of a compass held by a hand extending from a bank of clouds and inscribing a circle. The centre point of the compass indicates constancy, the moving point that creates the circle is the labour. Here are three examples from a collection of several volumes printed by Plantin in 1680. For more examples and commentary see HERE.