Graduation (scale)

A typical circular arc graduation is the division into angular measurements, such as degrees, minutes and seconds.

For durability and accuracy, etched or scribed marks are usually preferable to surface coatings such as paints and inks.

For example, it is common for black ink or paint to fill the grooves cut in a scribed rule.

[1] Later developments in devices such as dividing engines allowed the process to be automated with greater precision.

With proper concern for such effects as thermal expansion or contraction and shrinkage, the precision can be very high.