Imbedded circular hinge. Has strut, or friction leaf (.1 x 12.9 x 2.1 cm). Usual English-type double sector scales. Grouping of double scales is somewhat different than the norm. Lines of chords, secants, and equal parts on side (a) and lines of sines, tangents, and tangents of a smaller radius on side (b). "Pol" for line of polygons on (a) is engraved directly on the split. Line of polygons is marked by dots rather than divided lines. On single hour scale, "IIII" in Roman numerals is used instead of "IV" for four.
