Limbus (technology)
The limbus ( latin , thus something is enclosed or surrounded, the strip edge, seam boundary ; as degree circle or degree ring hereinafter) in measuring instruments into degrees divided arch or partial circle on which the size of the measured angle or radian read becomes.
It is a component of instruments for measuring apparent to microscopic distances. It can have a toothed periphery on which micrometer screws with a defined thread allow fractions of the graduation to be counted by precisely determined rotational thrust.