Graduations-Circle graduated to 360degs, 0-60 on both upper quadrants which are inscribed "UMBRA" & " VERSA", 0-60 on both lower quadrants which are inscribed "UMB. RECTA" & "UMB .RECTA", 3-10 is inscribed on centre part of instrument and indicated by a small pointer at centre of alidade. The alidade consists of three arms each having a fiducial edge. An ornamental suspension lig is attached to upper part of circle and a straight edge to lower part.
Sights- Two sight vanes 1" (2.5cm) long (one missing) are mounted on circle, each having a vertical slit. Two sight vanes 1" (2.5cm) long mounted on alidade , each having a vertical slit.
Compass-Dia. 1.5" (3.7cm) mounted on third arm of alidade. Fitted with a blued steel needle 1" (2.5cm) long, with a brass pivot cap at centre. Graduated quadrantally in degrees from E & W, 4 cardinal points (in Latin) are marked.