Surveying and Navigational Instruments

There are restrictions for re-using this image. For more information, visit the Smithsonian's Terms of Use page .
International media Interoperability Framework
IIIF provides researchers rich metadata and media viewing options for comparison of works across cultural heritage collections. Visit the IIIF page to learn more.
View manifest View in Mirador Viewer

By the sixteenth century, European makers of astronomical and navigational instruments sometimes included trigonometric scales on the instruments they made. The scales made it possible to look up values of functions such as the sine and the cosine, for use in computing heights. In Georg Hartman’s astrolabe of 1557, these functions are found on the rectangular shadow square on the back of the instrument. The back of an Iranian instrument from about 1715 has a grid of perpendicular lines that represent sines and cosines. Similar scales appeared on a form of sundial known as a horary quadrant.

Hartman's Planispheric Astrolabe

The astrolabe is an astronomical calculating device used from ancient times into the eighteenth century. Measuring the height of a star using the back of the instrument, and knowing the latitude, one could find the time of night and the position of other stars.
Description
The astrolabe is an astronomical calculating device used from ancient times into the eighteenth century. Measuring the height of a star using the back of the instrument, and knowing the latitude, one could find the time of night and the position of other stars. The openwork piece on the front, called the rete, is a star map of the northern sky. Pointers on the rete correspond to stars; the outermost circle is the Tropic of Capricorn, and the circle that is off-center represents the zodiac, the apparent annual motion of the sun. Engraved plates that fit below the rete have scales of altitude and azimuth (arc of the horizon) for specific latitudes. This brass astrolabe has four plates; one may well be a replacement. It was made in Nuremberg by Georg Hartman in 1537. An inscription on the inside of the instrument states that it once belonged to the Italian mathematician and astronomer Galileo Galilei (1564-1642).
Reference:
For a detailed description of this object, see Sharon Gibbs with George Saliba, Planispheric Astrolabes from the National Museum of American History, Washington, D.C.: Smithsonian Institution Press, 1984, pp. 146-150. The object is referred to in the catalog as CCA No. 262.
Location
Currently not on view
Date made
1537
possible owner
Galilei, Galileo
maker
Hartman, Georg
ID Number
MA.336117
catalog number
336117
accession number
215454

Persian Planispheric Astrolabe

This astrolabe was made in the Persian city of Isfahan in about 1715. Isfahan is now in Iran. The object includes a body with throne, a handle that holds a ring for suspending the device, and five plates.
Description
This astrolabe was made in the Persian city of Isfahan in about 1715. Isfahan is now in Iran. The object includes a body with throne, a handle that holds a ring for suspending the device, and five plates. One side of one plate has quarter horizons for every three degrees of latitude between twelve degrees and sixty-six degrees. The remaining faces of the plates show a stereographic projection of circles on the celestial sphere for latitudes from twenty-nine degrees to forty degrees. The astrolabe also has a rete or star map, an alidade on the back for sighting stars, a pin that passes through the center, and a wedge that holds the pin in place.
The upper left quadrant of the back of the astrolabe contains a grid of lines. Horizontal lines represents sines of angles, vertical ones cosines. The rectangular box below the center of the back includes a scales of tangents and cotangents of angles.
For a detailed description of the instrument, see Gibbs and Saliba.
The maker, ‘Abd al-A’imma, is well known in the history of Persian astrolabe making, although little biographical information survives. The Smithsonian acquired the instrument from the collection of Samuel V. Hoffman in 1959. It is number CCA40 on the international computerized checklist of astrolabes.
Compare 333589, 336114, and 316761 which are all by the same maker.
References:
For a detailed description of this object, see Sharon Gibbs with George Saliba, Planispheric Astrolabes from the National Museum of American History, Washington, D.C.: Smithsonian Institution Press, 1984, pp. 74-77. The object is referred to in the catalog as CCA No. 40.
Another astrolabe associated with the maker is described on
Astrolabe Catalog of the Oxford Museum of the History of Science, at www.mhs.ox.ac.uk, accessed March 2, 2016.
Location
Currently not on view
date made
ca 1715
ID Number
MA.316761
catalog number
316761
accession number
215454

Gunter Quadrant

This seventeenth century boxwood Gunter-type quadrant has two brass sights along the side of one radius. There is a hole drilled in the side of the quadrant between the sights. The plumb-bob and string which belong at the vertex are missing.
Description
This seventeenth century boxwood Gunter-type quadrant has two brass sights along the side of one radius. There is a hole drilled in the side of the quadrant between the sights. The plumb-bob and string which belong at the vertex are missing. The quadrant contains a geometric square marked from 10 to 50 to 10 in units of 2 degrees, an hour arc from 1 to 6 to 12 and an azimuth arc from 20 to 90 to 120, an ecliptic arc calibrated by zodiac symbol, a declination scale to 24 degrees, a horizon arc marked from 10 to 30, a second hour arc marked from 4 to 12 and arc marked from 10 to 50 by 10 degrees, a calendar arch named by month, and a circumference marked from 0 to 90 in units of one-half degree. There are two small "beetles" on either side of the calendar arc which may possibly be a maker's mark. This dial was made for a latitude of approximately 52 degrees.
Reference:
Abraham Rees, "Quadrant," Cyclopaedia (London, 1819), vol. 29.
The Whipple Museum of the History of Science, Catalogue 6: "Sundials and Related Instruments," Part 4, Section 3, "Horary Quadrants."
Location
Currently not on view
date made
1600-1700
ID Number
MA.319017
catalog number
319017
accession number
236091

Gunter Quadrant

This brass Gunter-type horary quadrant has one brass sight on the top of the quadrant along one radius. There is no pinhole in this sight; it is completely solid. It appears that there was never a second sight. The plumb-bob and string which belong at the vertex are missing.
Description
This brass Gunter-type horary quadrant has one brass sight on the top of the quadrant along one radius. There is no pinhole in this sight; it is completely solid. It appears that there was never a second sight. The plumb-bob and string which belong at the vertex are missing. The quadrant contains a geometric square marked from 10 to 50 to 10 in units of one degree, an hour arc (U-shaped) from I to VI to XI to XII and an azimuth arc from 30 to 90 to 120 by ten degrees, an ecliptic arc calibrated by zodiac symbol, a declination scale to 24 degrees, a horizon arc marked from 10 to 30, a second hour arc marked from VIII to I, a calendar arch lettered by month, and a circumference marked from 0 to 90 in units of one-half degree. There are suns between most Roman numerals on the hour arcs, moons on each side of the calendar arch, and sets of three dots at each 5-degree mark on the circumference. Five stars are charted: VH, BE, LH, A, PW. This dial was made for a latitude of approximately 52 degrees. There is no instrument maker with initials T. D. who worked around 1790 in Clifton, or in the inventory of the National Maritime Museum, Greenwich.
References:
Gloria Clifton, Directory of British Scientific Instrument Makers..., Greenwich: National Maritime Museum, 1995.
An Inventory of the Navigation and Astronomy Collections in the National Maritime Musuem, Greenwich, National Maritime Museum.
Location
Currently not on view
date made
1790
ID Number
MA.330843
catalog number
330843
accession number
305777

Turkish Horary Quadrant

This undated Turkish quadrant is made of yellow paper lacquered to a wooden base. Lines, script, and numerals are marked in red and black pigment. All markings are in Arabic. The edges are painted red. One edge is indented, serving to sight the sun.
Description
This undated Turkish quadrant is made of yellow paper lacquered to a wooden base. Lines, script, and numerals are marked in red and black pigment. All markings are in Arabic. The edges are painted red. One edge is indented, serving to sight the sun. A hole near the square corner would hold a plumb bob.
One side of the quadrant contains scales for declination and right ascension, azimuth arcs, an ecliptic arc, and hour arcs. The circumference is calibrated from zero to ninety by single degree in groups of five.
The reverse contains a grid for reading off sines and cosines. It also has two semicircles at right angles to each other, an arc connecting the twenty-fourth mark on each axis, and two red lines sloping up to the right. Numerous dots are at points of intersection on the grid. Both axes of the grid are marked in groups of five units. The circumference on this face is also calibrated from zero to ninety degrees by degree in groups of five.
References:
A similar horary quadrant is at the Museum of the History of Science of Oxford University. , inventory number 35612 (accessed 29 February 2016).
Glen van Brummelen, The Mathematics of the Heavens and the Earth: The Early History of Trigonometry, Princeton and Oxford: Princeton University Press, 2009, esp. pp. 209-211.
A similar instrument in the collections of the Greenwich Maritime Museum is described in Hester Higton, Sundials at Greenwich, Oxford: Oxford university Press, 2002, esp. pp. 368-369.
Location
Currently not on view
ID Number
MA.317639
catalog number
317639
accession number
231062

Secoes Holland Circle

In the late 16th century, a Dutch scholar and instrument maker named Gemma Frisius suggested that a good surveying instrument could be made by attaching a magnetic compass to the back of an astrolabe.
Description
In the late 16th century, a Dutch scholar and instrument maker named Gemma Frisius suggested that a good surveying instrument could be made by attaching a magnetic compass to the back of an astrolabe. Building on this idea, Jan Dou designed an instrument with two pairs of fixed sights attached to a graduated circle, and another pair of sights attached to either end of a movable alidade. Dou published an account of this instrument in Dutch in 1612, and the form became popular with surveyors in the Netherlands. The name Holland Circle was coined in the 19th century. The Holland Circle is similar to but easily distinguishable from the common theodolite.
The outer circle of this Holland circle is graduated every thirty minutes, and has additional scales for tangents, sines, and secants. The small compass in the center has a fleur–de–lis at north, and an offset line probably indicating magnetic variation. The signature reads "JACOB SECOES" and "ANNO 1622."
Location
Currently not on view
date made
1622
maker
Secoes, Jacob
ID Number
PH.317347
catalog number
317347
accession number
230279

Graphometer

Like a standard graphometer, this one has a graduated semicircle, a pair of fixed sights, and an alidade with sights at either end. The semicircle is graduated to 30 minutes, and read by verniers at either end of the alidade to two minutes.
Description
Like a standard graphometer, this one has a graduated semicircle, a pair of fixed sights, and an alidade with sights at either end. The semicircle is graduated to 30 minutes, and read by verniers at either end of the alidade to two minutes. There is a trough compass, two level vials, and an outkeeper. Unlike a standard graphometer, however, the fixed sights here are attached to the underside side of the plate, the alidade is graduated and equipped with a secondary rule and quadrant, and the face is covered with a grid.
The inscriptions read "J. M. LILLEY'S PATENT NOV. 10 1857" and "F. W. & R. KING BALTIMORE 26." The title of the patent (#18,608) granted to James M. Lilley (1802-1875) of Greenville, Va., on November 10, 1857, describes an "Improved Instrument for Surveying and Calculating Areas." The text refers to a new and improved "Compass" that is "intended to facilitate calculation of oblique-angled trigonometry and finding the area of triangles." The patent drawing refers to an "Altitude Instrument."
F. W. & R. King were in business in Baltimore from 1849 to 1875, selling camera equipment and instruments for surveyors and engineers. The Department of Civil Engineering of the University of Missouri at Rolla donated this instrument to the Smithsonian in 1994.
Location
Currently not on view
date made
1857-1875
maker
F. W. & R. King
ID Number
1994.0377.01
accession number
1994.0377
catalog number
1994.0377.01

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.