sector with folding square
Date1760-1770
Inventory NumberDW0501
ClassificationSector
Subject
Maker
Benjamin Martin
1704 - 1782
Cultural Region
Place of Origin
Dimensionsclosed: 0.4 x 24.5 x 6.1 cm (3/16 x 9 5/8 x 2 3/8 in.)
Material
Credit LineGift of David P. Wheatland
DescriptionThis English sector is made of brass and rather banged up. A rectangular blade folds out from the upper arm and rotates until it forms a square with that arm. It can also be set into a slot at the end of the lower arm (or placed halfway within the upper 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 longitude ("Lon")
line of artificial tangents ("Tan.")
line of artificial sines ("Sines")
line of artificial versed sines ("Ver. Sin.")
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 Mer")
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 longitude ("Lon")
line of artificial tangents ("Tan.")
line of artificial sines ("Sines")
line of artificial versed sines ("Ver. Sin.")
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 Mer")
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.
In Collection(s)
Signedon upper arm: B Martin London
Curatorial RemarksXRF analysis of the metals was done by Katherine Eremin and Sara Schechner in August 2007.
FunctionCalculation
ProvenanceDavid Wheatland purchased from Saul Moskowitz, Marblehead, Massachusetts, July 7, 1975. Donated to CHSI 1985.
English
Date: 1775-1800
Accessories: case contains the following nine instruments: one ivory and brass sector; one ivory and brass parallel rule; one brass protractor; two pairs of dividers, one with pen holder, pencil holder, and inking wheel (for drawing dotted line) attachments; and pen.
Object number: 5458
George Adams (I)
Date: circa 1766
Accessories: original case
Object number: DW0955
Gilson Slide Rule Company
Date: 1915-1919
Object number: 1989-1-0006
Tavella Sales Company
Date: copyright 1934
Accessories: black leather case with snap closure, instruction manual (in file)
Object number: 2003-1-0244
Tavella Sales Company
Date: dated 1944
Accessories: brown fabrikoid case; postmarked order form and advertisement for Mascot slide rule
Object number: DW0968