A dividing engine is a device employed to mark graduations on measuring instruments.
Dividing engine at the Michigan Museum of Surveying
Dividing engine at the Museo Galileo in Florence.
Circular Dividing Engine
A graduation is a marking used to indicate points on a visual scale, which can be present on a container, a measuring device, or the axes of a line plot, usually one of many along a line or curve, each in the form of short line segments perpendicular to the line or curve. Often, some of these line segments are longer and marked with a numeral, such as every fifth or tenth graduation. The scale itself can be linear or nonlinear.
A slide rule. This is an example of a mathematical instrument with graduated logarithmic and log-log scales.
A half circle protractor graduated in degrees (180°).