Ivory sector by Isaac Carver

Made:
1668-1713 in London
maker:
Isaac Carver
Sector, 6"; ivory and brass; engraved "Carver Fecit"

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Sector, 6"; ivory and brass; engraved "Carver Fecit"
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Six-inch sector made by Isaac Carver, London, 1668-1713, and signed "Carver Fecit".

The sector has two types of scale, namely edge scales and others parallel to the edges, and sectoral scales, the latter radiating from a single point, the centre of the hinge. This sector also has some scales between the sectoral and edge ones that are unlabelled. On the front the edge scale is a twelve inch by tenths ruler. The sectoral scales are chords (labelled “C”), natural secants (labelled “Sec”), a linear scale (labelled “L”) and a segment scale (labelled “Seg”). On the reverse the edge scale is a Gunter logarithmic scale. The sectoral scales are polygons (labelled”POLL”), two tangent scales (labelled “T” and “tan”) and a sin scales (labelled “S”).

The sector was a versatile calculating instrument that could be used for a wide range of arithmetical, trigonometrical and geometrical calculations. Most calculations were performed with the sector partially opened and the aid of a pair of dividers. This is a relatively early example of an English sector and the s scale and layout differ to some extent from the layout that had become standard by the mid-eighteenth century.

Details

Category:
Mathematics
Object Number:
1917-92
Materials:
brass, complete and ivory
Measurements:
Closed: 45 mm x 165 mm x 20 mm,
Open: 70 mm x 165 mm x 20 mm, 0.085 kg
type:
sectors
credit:
Thomas H. Court