Combined graphometer and plummet clinometer, 1663.

Combined graphometer and plummet clinometer by Christoff Kohler of Dresden, 1663

This instrument was made by Christoff Kohler of Dresden in 1663. Circumferentors (with a complete circle scale) and graphometers (with a half circle scale) were widely used through the 17th and 18th centuries for angle measurement. A joint on the support allowed for both vertical and horizontal use. The clinometer was used for measuring the angle or elevation of slopes. The semi-circular scale, provided with fixed and moveable sights, can be detached and used as a protractor for plotting angles in the field. The inscription engraved on back of the object reads 'Christoff Kohler Mech Dresten Fecit'. The instrument carries a simple quadrant clinometer on the reverse side, for measuring the inclination of the line of vision when sighting a distant object.

in 1597, Danfrie published details of a gramophometer which was in effect a circumferentor with a semi-circular scale instead of a complete circle. This instrument was comparatively easy to make and use. It soon gained a considerable measure of popularity among surveyors, so much so that graphometers were still being made in the early years of the nineteenth century. although theodolites of quite advanced design were readily available by that time.