sector with folding square
Date: 1806-1819
Inventory Number: DW0952
Classification: Sector
Subject:
Maker: Gilbert & Sons (1806 - 1819)
Cultural Region:
Place of Origin:
Dimensions:
closed: 0.4 x 32.8 x 8.4 cm (3/16 x 12 15/16 x 3 5/16 in.)
Material:
DescriptionThis English sector is made of brass. A rectangular blade folds out from the lower arm and rotates until it forms a square with that arm. It can also be set into a slot at the end of the upper arm (or placed halfway within the lower arm) in order to serve as a friction blade to hold the arms at a set opening.
The sector is engraved with the following scales:
side a:
line of natural sines ("Sin.")
small line of natural tangents ("tan.")
line of natural tangents ("Tan.")
line of rhumbs ("Rum")
line of longitudes ("Lon.")
line of artificial tangents ("Tangts.")
line of artificial sines ("Sines")
line of artificial versed sines ("V. Sines")
Gunter's line of numbers ("Num.")
side b:
line of lines ("Lin"), also known as line of equal parts
line of natural secants ("Sec.")
line of chords ("Cho.")
line of polygons ("POL.")
scale of inches (unlabeled)
scale of a foot divided into 100 equal parts (unlabeled)
line of inclinations of meridians ("In. Me.")
small line of chords ("Cho.")
small line of artificial sines ("Sin.")
small line of artificial tangents ("Tan.")
line of latitudes ("Lat.")
line of hours ("Hou.")
long line of chords ("Cho.")
The sector hinge is plain.
The sector is engraved with the following scales:
side a:
line of natural sines ("Sin.")
small line of natural tangents ("tan.")
line of natural tangents ("Tan.")
line of rhumbs ("Rum")
line of longitudes ("Lon.")
line of artificial tangents ("Tangts.")
line of artificial sines ("Sines")
line of artificial versed sines ("V. Sines")
Gunter's line of numbers ("Num.")
side b:
line of lines ("Lin"), also known as line of equal parts
line of natural secants ("Sec.")
line of chords ("Cho.")
line of polygons ("POL.")
scale of inches (unlabeled)
scale of a foot divided into 100 equal parts (unlabeled)
line of inclinations of meridians ("In. Me.")
small line of chords ("Cho.")
small line of artificial sines ("Sin.")
small line of artificial tangents ("Tan.")
line of latitudes ("Lat.")
line of hours ("Hou.")
long line of chords ("Cho.")
The sector hinge is plain.
Signedon upper arm: Gilbert & Sons
on lower arm: London
on lower arm: London
FunctionCalculation
Curatorial RemarksXRF analysis of the metals was done by Katherine Eremin and Sara Schechner in August 2007.