This sector includes all the single and double scales found on a standard pattern English sector, and eight additional scales.  These extra scales consist of four for sundial construction: Latitude, hours, inclinations of meridians, and an associated scale of chords. With this group are two further short scales be used in conjunction with them, a scale of sines, and a scale of tangents to 45 degrees.

On the signature side of the sector, there are two navigation scales; a scale of rhumbs and a longitude scale.  These normally appear on a maritime gunter's rule, rarely on a sector sector.

A very small proportion of sectors, usually those associated with extensive "campaign" sets of drawing instruments, have the four additional sundial scales.  It is very unusual to have further scales.

Further details:  This is a finely engraved six inch brass sector with third arm, the engraving is still crisp and clear. There are a number of small edge knocks, and scratches, which are shown in the photos.  At 1.55 inches (39.5mm) wide when closed, the instrument is a little wider than the average sector, to accommodate the extra scales.  Ganymede stock no, 35-3872.