Graphometer-clinometer, c 1600.
© Science Museum / Science & Society Picture Library
Circumferentors (with a full circle scale) and graphometers (with a half circle scale) such as this example made by Philippe Danfrie, were widely used in the 17th and 18th centuries for angle measurement. A joint on the support allowed for both vertical and horizontal use. Philippe Danfrie is credited with the original design of the graphometer, publishing a book on the subject in the 1590s.