English Style

Although they gradually disappeared from the instrument, scales for making sundials were the most distinctive feature of sectors made in England. These included scales for hours, chords, latitude, and the inclined meridian. Edmund Gunter, who is credited with inventing the English sector, devised logarithmic scales on which calculations could be made with the aid of dividers. These scales later ended up on slide rules, thanks to William Oughtred and others. On sectors, the scales included logarithmic numbers, sines, and tangents. Finally, unlike the other styles of sectors, the English style provided tools for trigonometry (tangent, sine, and secant) and for navigation (rhumbs and longitude).

This brass instrument has straight ends, and the hinge is decorated with a floral design. A rectangular brass piece fits between the arms when the sector is closed and swivels out to form a square corner when the sector is opened.
Description
This brass instrument has straight ends, and the hinge is decorated with a floral design. A rectangular brass piece fits between the arms when the sector is closed and swivels out to form a square corner when the sector is opened. The piece also fits into the groove on the other arm to hold the sector open at a fixed acute angle. One side has three double scales. Two are tangent scales, running from 45 to 75 degrees and from 10 to 45 degrees. The third is a sine scale, running from 10 to 90 degrees. The top of the upper arm has scales for hours, running from I to VI, and for chords, running from 10 to 90. The bottom of the lower arm has scales labeled "Latt" and "In : M." Both scales run from 10 to 90. These four scales were used for making sundials and are unique to sectors made in England. The sector is marked: R : Glynne : Fecit.
The other side has double scales labeled "Poll," running from 6 to 12; "sec," running from 20 to 75; "Lin," running from 2 to 10 on the upper arm and from 1 to 10 on the lower arm; and "Cho," running from 10 to 60. The "Poll" scale is not the usual scale for the side length of inscribed polygons, as the numbers start with 6 rather than with 3 and increase from the center to the ends of the legs instead of decreasing. The scale of chords is outside the scale of equally divided lines on the upper arm and inside the scale of equally divided lines on the lower arm. Three logarithmic scales are along the outer edge: "Tan," running from 1 to 45; "Sim" [sic], running from 1 to 80 (which is marked "60"); and "Num," running from 1 to 10 twice and then from 10 to 30. The outside face of the rule has a scale of inches that runs from 1 to 12 and is divided to tenths of an inch.
The London workshop operated by Richard Glynne (1681–1755) made globes, sundials, and drawing instruments. Glynne was in partnership with Anne Lea, his mother-in-law, from about 1712 to 1725, and he became so successful that he retired in 1729. For a sundial signed by Henry Wynne, under whom Glynne apprenticed from 1696 to 1705, see 1987.0851.01.
References: Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/; E. G. R. Taylor, The Mathematical Practitioners of Tudor & Stuart England (Cambridge: University Press, 1970), 293; Gloria Clifton, Directory of British Scientific Instrument Makers 1550–1851 (London: National Maritime Museum, 1995); Bruce Babcock, "A Guided Tour of an 18th-Century Carpenter's Rule," Journal of the Oughtred Society 3, no. 1 (1994): 26–34.
Location
Currently not on view
date made
1712-1729
maker
Glynne, Richard
ID Number
1990.0572.01
accession number
1990.0572
catalog number
1990.0572.01
The silver hinge is undecorated on this ivory instrument with rectangular arms. On one side and from the top down, each arm has a sine scale, running from 10 to 90 degrees; a tangent scale, running from 45 to 75 degrees; and a second tangent scale, running from 10 to 45 degrees.
Description
The silver hinge is undecorated on this ivory instrument with rectangular arms. On one side and from the top down, each arm has a sine scale, running from 10 to 90 degrees; a tangent scale, running from 45 to 75 degrees; and a second tangent scale, running from 10 to 45 degrees. Spanning both arms on the outer edge are three scales: log tangent, running from 2 to 30 degrees; log sine, running from 1 to 70 degrees; and logarithmic, labeled num and running from 1 to 10 twice and then from 10 to 20. The hinge is marked: Ramsden (/) London.
The other side has a double scale along the fold line for regular polygons, from 12 to 4 sides. Each arm has a scale of equal parts, running from 1 to 10 and labeled L; a secant scale, running from 20 to 75 and labeled s; and a scale of chords, running from 10 to 60 and labeled C. The upper arm has scales labeled IM and Cho that each run from 10 to 90. The lower arm has scales labeled Lat, running from 10 to 70; and Hou, running from I to VI. These four scales are associated with making sundials. Spanning both arms on the outer edge is a scale of inches, running from 11 to 1 and divided to tenths of an inch.
After training under several notable makers of instruments, Ramsden operated his own shop from before 1765 to 1800. His equatorial telescopes and sextants were of especially high quality, and he invented a dividing engine for engraving angular divisions on circular instruments. The second model for his dividing engine is now owned by the Smithsonian, MA.215518.
The object was purchased in 1960.
References: Gloria Clifton, Directory of British Scientific Instrument Makers 1550–1851 (London: National Maritime Museum, 1995), 277; Anita McConnell, Jesse Ramsden (1735–1800): London's Leading Scientific Instrument Maker (Aldershot, England: Ashgate, 2007); Randall C. Brooks, "Dividing Engine," in Instruments of Science: An Historical Encyclopedia, ed. Robert Bud and Deborah Jean Warner (New York and London: Garland Publishing, 1998), 184–186.
Location
Currently not on view
date made
1765-1800
maker
Ramsden, Jesse
ID Number
MA.317364
catalog number
317364
accession number
230278
This brass instrument has two arms with flat edges, an undecorated hinge, and a central crossbar attached to the end of one arm that fits into a notch on the other arm to hold the sector open at a fixed acute angle.
Description
This brass instrument has two arms with flat edges, an undecorated hinge, and a central crossbar attached to the end of one arm that fits into a notch on the other arm to hold the sector open at a fixed acute angle. On one side and from the top down, each arm has a sine scale, running from 10 to 90 degrees; a tangent scale, running from 45 to 75 degrees; and a second tangent scale, running from 10 to 45 degrees. The top arm has a scale labeled "Rum." that runs from 1 to 8, and the lower arm has a scale labeled "Lon." that runs from 60 to 10. Spanning both arms on the outer edge are three scales: log tangents, running from 1 to 45 degrees and labeled "Tan."; log sines, running from 1 to 75 degrees and labeled "Sines"; and logarithmic, running from 1 to 10 twice and labeled "Num." This side is marked: Wm. Harris Holborn (/) London.
The other side has a double scale along the fold line for regular polygons, from about 8 to 4 sides. Each arm has a "line of lines" scale, running from 1 to 10; a secant scale, running from 30 to 75; and a scale of chords, running from 10 to 60. The upper arm has scales for the inclined meridian, chords, and sines, each running from 10 to 90. The lower arm has scales for tangents, running from 10 to 45; latitude, running from 10 to 90; and hours, running from I to VI. Spanning both arms along the outer edge is a scale of equal parts, running from 90 to 10; and a scale of inches, running from 12 to 1 and divided to tenths of an inch. On both sides of the instrument, the scales are small, worn, and difficult to read.
William Harris owned a workshop that made spectacles, telescopes, and mathematical and philosophical instruments on High Holburn Street in London from 1799 to 1839, when the workshop was renamed William Harris & Son.
References: Gloria Clifton, Directory of British Scientific Instrument Makers 1550–1851 (London: National Maritime Museum, 1995), 126; Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/.
Location
Currently not on view
date made
1799-1839
maker
Harris, William
ID Number
1988.0533.01
catalog number
333943
accession number
1988.0533
This large brass instrument has two rectangular arms with flat ends and an undecorated hinge.
Description
This large brass instrument has two rectangular arms with flat ends and an undecorated hinge. On one side and from the top down, each arm has a sine scale, running from 10 to 90 degrees; a tangent scale, running from 45 to 75 degrees; and a second tangent scale, running from 10 to 45 degrees. The top arm has a scale labeled "Rum." that runs from 1 to 8, and the lower arm has a scale labeled "Lon." that runs from 60 to 10. Spanning both arms on the outer edge are four scales: log tangents, running from 1 to 45 degrees; log sines, running from 1 to 90 degrees; log versed sines, running from 165 to 10 degrees; and logarithmic, labeled "Num." and running from 1 to 10 twice. The front is marked: Thos. Harris & Son (/) British Museum London.
The other side has a double scale along the fold line for regular polygons, from 12 to 4 sides. Each arm has a "line of lines" scale, running from 1 to 10; a secant scale, running from 10 to 75; and a scale of chords, running from 10 to 60. The upper arm has a scale of equal parts, running from 90 to 10, and scales for the inclined meridian, chords, and sines, each running from 10 to 90. The lower arm has scales for tangents, running from 10 to 45; latitude, running from 10 to 90; hours, running from I to VI; and chords, running from 0 to 180. Spanning both arms along the outer edge is a scale of inches, running from 24 to 1 and divided to twentieths of an inch.
The London telescope maker Thomas Harris (about 1750–1827) took his son, William, as a partner in 1806. By 1817, the firm was located on Great Russell Street, across from the entrance to the British Museum, and presented itself as "opticians to the Royal Family." In 1846, the workshop moved to High Holburn Street; it remained in business until the 20th century.
References: Gloria Clifton, Directory of British Scientific Instrument Makers 1550–1851 (London: National Maritime Museum, 1995), 125–126; Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/.
Location
Currently not on view
date made
1806-1846
maker
Thomas Harris & Son
ID Number
MA.316747
catalog number
316747
accession number
227807
This ivory instrument has two rectangular arms with flat edges and a circular brass hinge. The scales run from top to bottom on each arm, unlike the paired double scales on Italian and French sectors.
Description
This ivory instrument has two rectangular arms with flat edges and a circular brass hinge. The scales run from top to bottom on each arm, unlike the paired double scales on Italian and French sectors. On one side, each arm has a sine scale, running from 10 to 90 degrees; a tangent scale, running from 45 to 75 degrees; and a second tangent scale, running from 10 to 45 degrees. Spanning both arms on the outer edge are three scales: log sine, running from 2 to 70 degrees; log tangent, running from 1 to 45 degrees; and logarithmic, running from 1 to 10 twice and then from 10 to 20. The top face of the instrument has a scale of equal parts that runs from 100 to 10. The front is marked: *Gilkerson* (/) Tower-Hill-London.
The other side has a double scale along the fold line for regular polygons, labeled POL and running from 12 to 4 sides. Each arm has a scale of equal parts, running from 1 to 10 and labeled L; a secant scale, running from 20 to 75 and labeled s; and a scale of chords, running from 10 to 60 and labeled C. The upper arm has scales labeled Im and Ch that each run from 10 to 90. The lower arm has scales labeled La, running from 10 to 70; and H, running from I to VI. These four scales (inclinations of meridians, chords, latitudes, and hours) are associated with making sundials. Spanning both arms on the outer edge is a scale of inches, running from 11 to 1 and divided to tenths of an inch.
James Gilkerson was in business in Tower Hill, London, from 1809 to 1825. Donor Ada B. Richey reported that her husband's ancestor, Lt. Col. Alexander Matheson (b. 1788), was the original owner of this drawing instrument. He settled in Perth, Canada, after serving in the British army during the War of 1812.
References: Gloria Clifton, Directory of British Scientific Instrument Makers 1550–1851 (London: National Maritime Museum, 1995), 113; J. F. Heather, Mathematical Instruments: Their Construction, Adjustment, Testing, and Use, rev. ed. (London: Crosby Lockwood and Co., 1870), i:42–52; Samuel Sturmy, "The Art of Dialling," The Mariner's Magazine (London, 1669).
Location
Currently not on view
date made
1809-1825
maker
Gilkerson, James
ID Number
MA.321756
accession number
243754
catalog number
321756

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.