Universal equinoctial sundial, Danish, 18th century.
© Science Museum / Science & Society Picture Library
This sundial is signed 'Carl Von Mandern fecit Hafnia', from Copehagen, Denmark. Equinoctial sundials have a slanted dial and a gnomon, or pointer, which is at right angles to the dial. Sundials were accurate enough timekeepers for most people in the 18th century. They varied in size and type, from large dials on the sides of churches to small, intricate dials.