Base-Dia. 11.75" (29.8cm) graduated to 360 degs by 1'. Fitted with an alidade at centre 10.75" (27.3cm) long, with a vernier scale at one end graduated 60-30, 30-0.
Compass- Dia. 5.9" (15cm) mounted at centre of alidade. Fitted with a blued steel needle with a brass pivot cap at centre, graduated to 8 points, quadrantally in degrees, and anti-clockwise to 360 degs. Fitted with two spirit levels in brass casings 2" (5.1cm) long, one mounted at N point E-W, the other at E point N-S.
Vertical arc-Radius 3.5" (8.9cm) carried on a brass framework above alidade. Graduated on one side 30-0-30 and on the other 50-0-50. A "T" shaped brass frame is pivoted at apex of framework, the lower arm of which forms an index bar to the graduated arc, and the upper flat section forms the mounting for the telescope (missing).