Brass body with alloy fittings and ivory (?) plates on front and back.
Scales:
1. Height scale on fixed horizontal metal bar across moveable distance scale graduated from 0-220 f. On this bar is a sliding pointer.
2. Radial distance scale graduated 1/4-30 cables.
3. Advance/Drop scale graduated from 0-100, and from 0-200. This is carried on a revolving metal spindle operated by a milled knob, on the left-hand side of instrument. This scale is used in conjunction with the Mountbatten Station Keeping System.
Optics: a long curved lens attached to the radial distance is mounted in a moveable slide. A pinion, carried on the spindle of a milled knob, engages a rack to provide this movement. A fixed wedge-shaped lens is mounted alongside the moving lens on the frame of the instrument. A small telescope with an interrupted thread can be inserted in a metal collar. The onject when viewed, appears as a superimposed image.
On reverse side is a blank table for inserting relevant data concerning ships likely to be observed.
In fitted mahogany box 7.75 x 4.7 x 1.9" (19.7 x 11.11 x 5cm)