- Subject
- Calculation
- Item type
- Object
- Makers
- John Allen
- Primary inscriptions
- Signed "Iohn Allen fecit" across hinge.
- Physical material
- Brass
- Object type
- Sector
- Dimensions
- Height: 244mm Width: 60mm Depth: 5mm
- Inventory No
- 51763
Description
Brass 9 inch sector with folding support strut.
The signed side carries sectoral scales for sines (Sin), areas (Super), chords (Cho), an unlabelled scale (5 to 10) and a scale (labelled Q for quadrature?) straddling the two legs, perhaps for inscribed polygons. It is notable that the scales alternate between dotted single lines and scales which are multiply-lined and divided. The same side has single scales for tangents (Tang) and secants (Secan). The reverse has sectoral scales of equal parts (Lin), solids (Solid) and metals, with the inscription of regular polyhedra in a sphere straddling the two legs. The format of the scales again alternates. This side has single scales of the meridian (merid), logarithmic numbers (N), tangents (T) and sines (S). One outer edge carries a scale of inches, the other may be logarithmic numbers.
