Measuring & Mapping

Vernier Compass

Where, how far, and how much? People have invented an astonishing array of devices to answer seemingly simple questions like these. Measuring and mapping objects in the Museum's collections include the instruments of the famous—Thomas Jefferson's thermometer and a pocket compass used by Meriwether Lewis and William Clark on their expedition across the American West. A timing device was part of the pioneering motion studies of Eadweard Muybridge in the late 1800s. Time measurement is represented in clocks from simple sundials to precise chronometers for mapping, surveying, and finding longitude. Everyday objects tell part of the story, too, from tape measures and electrical meters to more than 300 scales to measure food and drink. Maps of many kinds fill out the collections, from railroad surveys to star charts.

Place: England

Sextant

This sextant is somewhat unusual in that it has a brass frame, reinforced brass index arm, and ivory (rather than metal) scale. This scale is graduated every 20 minutes from -5° to +125° and read by vernier with tangent screw and swinging magnifier to 30 seconds of arc.
Description
This sextant is somewhat unusual in that it has a brass frame, reinforced brass index arm, and ivory (rather than metal) scale. This scale is graduated every 20 minutes from -5° to +125° and read by vernier with tangent screw and swinging magnifier to 30 seconds of arc. The "Spencer Browning & Co., London" inscription on the arc refers to a firm that was in business from 1840 to 1870.
Location
Currently not on view
date made
1840-1870
maker
Spencer, Browning & Co.
ID Number
1981.0942.01
catalog number
1981.0942.01
accession number
1981.0942

Telescope (Spyglass)

The tube of this telescope consists of two threaded wooden (mahogany) sections screwed together that measure 113 cm (closed) or 117.5 cm (fully extended). The achromatic objective lens measures 3.5 cm in diameter (or 3.4 cm clear diameter).
Description
The tube of this telescope consists of two threaded wooden (mahogany) sections screwed together that measure 113 cm (closed) or 117.5 cm (fully extended). The achromatic objective lens measures 3.5 cm in diameter (or 3.4 cm clear diameter). The eyepiece consists of four lenses in a brass cylinder (5 separate brass cylinders, screwed together) with a sliding brass cover. The instrument gives gives an erect (terrestrial) image.
The "Nairne, London" inscription on the sliding brass lens cover refers to the important instrument maker, Edward Nairne (1726-1806).
Ref: D.J. Warner, "Edwarne Nairne: Scientist and Instrument Maker," Rittenhouse 12 (1998): 65-93.
Location
Currently not on view
maker
Nairne, Edward
ID Number
PH.325412
accession number
256202
catalog number
325412

Theodolite

This instrument is marked "L. Casella, Maker to the Admiralty & Ordnance LONDON 5227" and "U.S.C.&G.S." It was made between 1878, when the U. S. Coast Survey became the U. S. Coast and Geodetic Survey, and the death of Louis Casella in 1897.
Description
This instrument is marked "L. Casella, Maker to the Admiralty & Ordnance LONDON 5227" and "U.S.C.&G.S." It was made between 1878, when the U. S. Coast Survey became the U. S. Coast and Geodetic Survey, and the death of Louis Casella in 1897. Casella termed it a "Transit Theodolite . . . with achromatic telescope." New, it cost £24.
Ref: L. P. Casella, List of a Few Instruments in General Use, Selected from the General Catalogue of Standard Meteorological and Other Instruments for Observatories, Travelers and Explorers, and the Army and Navy (London, 1896), p. 26.
Location
Currently not on view
maker
Casella, Louis Paschal
ID Number
PH.309657
catalog number
309657
accession number
106954

Sextant

The sextant belonged to the University of Pittsburgh, a school that began as the Pittsburgh Academy in 1787. The frame is brass. The silvered scale is graduated every 15 minutes from -3° to +143° and read by vernier with tangent screw and swinging magnifier to 15 seconds of arc.
Description
The sextant belonged to the University of Pittsburgh, a school that began as the Pittsburgh Academy in 1787. The frame is brass. The silvered scale is graduated every 15 minutes from -3° to +143° and read by vernier with tangent screw and swinging magnifier to 15 seconds of arc. The inscription on the arc reads "Chapman London." There were several instrument makers and dealers named Chapman working in London during the middle decades of the 19th century. The trade card in the wooden box is that of Benjamin Pike, Jr., who was in business as an instrument dealer in New York from 1843 to 1864 and who probably imported this sextant into the U.S.
Location
Currently not on view
date made
mid 19th century
associated person
Pike, Jr., Benjamin
maker
Chapman
ID Number
PH.334886
catalog number
334886
accession number
315134

Theodolite

This is a standard theodolite as made by Troughton & Simms in the second quarter of the 19th century. The horizontal circle is silvered, graduated to 20 minutes, and read by two verniers with magnifiers to 20 seconds. The vertical arc is graduated and read in a similar manner.
Description
This is a standard theodolite as made by Troughton & Simms in the second quarter of the 19th century. The horizontal circle is silvered, graduated to 20 minutes, and read by two verniers with magnifiers to 20 seconds. The vertical arc is graduated and read in a similar manner. The scale "Diff. of Hypo. & Base" that appears on the back of the vertical arc is used to correlate the angle of elevation or depression with horizontal distances when surveying sloping ground. The instrument is marked "Troughton & Simms LONDON" and "No. 1" (which was probably added by a former owner).
Location
Currently not on view
date made
1825-1850
maker
Troughton and Simms
ID Number
PH.330222
catalog number
330222
accession number
288699

Howells, Barraud & Jamison Marine Chronometer

In the 18th century, inventing a practical way to determine time and place was so important to the security of seafaring imperial nations of Western Europe that a number of governments established lucrative prizes to inspire a solution.John Harrison received England's prize for i
Description
In the 18th century, inventing a practical way to determine time and place was so important to the security of seafaring imperial nations of Western Europe that a number of governments established lucrative prizes to inspire a solution.
John Harrison received England's prize for inventing a timepiece accurate enough for determining longitude at sea. Harrison's timekeepers were ingenious, intricate and difficult to reproduce accurately and affordably. Nevertheless, they paved the way for the work of later inventor watchmakers, all of whom would help to revolutionize the maritime world by producing the timepieces that came to be known as marine chronometers.
Thomas Mudge, one of the watchmakers following Harrison, designed this instrument. Like Harrison's timepieces, Mudge's were extremely inventive and complex. And like Harrison, Mudge won an English government prize he had a struggle to receive.
Mudge's son, Thomas Mudge Jr., engaged a number of craftsmen to make copies of his father's work for public sale. The venture was a financial failure. The copies never accomplished the superior accuracy of the senior Mudge's own work, although their performance was adequate for maritime purposes.
Of the twenty-six copies of his father's design commissioned by the younger Mudge, this one is number fourteen. It is the product of a collaboration of three craftsmen: William Howells of Kennington in southeast London, Paul Philip Barraud also of London and George Jamison of Portsea, a town adjacent to the naval base of Portsmouth on the southern English coast. Marks on the timekeeper's movement indicate they completed it in London in 1802.
A plain wood box protects the instrument, which hangs in a framework of partial gimbals to keep it level on a rolling ship.
Location
Currently not on view
date made
1802
maker
Jamison, George
Barraud, Paul Philip
Howells, William
ID Number
ME.322384
accession number
247659
catalog number
322384

Sextant

Sextant with a brass frame. The silvered scale is graduated every 10 minutes from -5° to +155° and read by vernier with tangent screw and magnifier to 10 seconds of arc. The inscriptions read "Troughton & Simms, London" and "Silver."Currently not on view
Description
Sextant with a brass frame. The silvered scale is graduated every 10 minutes from -5° to +155° and read by vernier with tangent screw and magnifier to 10 seconds of arc. The inscriptions read "Troughton & Simms, London" and "Silver."
Location
Currently not on view
date made
1836-1900
maker
Troughton & Simms
ID Number
PH.328886
catalog number
328886
accession number
277637

Octant

Octant with a rosewood frame, flat brass index arm, and ivory name plate. The ivory scale is graduated every 20 minutes from -5° to +95° and read by vernier to 2 minutes of arc.
Description
Octant with a rosewood frame, flat brass index arm, and ivory name plate. The ivory scale is graduated every 20 minutes from -5° to +95° and read by vernier to 2 minutes of arc. The inscription reads "Made by Thos Ripley London For Frans Earle July 21st 1784." Thomas Ripley was in business from 1765 to 1790, offering mathematical and optical instruments. Caroline Bates, the widow of Major General Alfred Elliott Bates, gave this to the Smithsonian in 1916.
Ref: Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London, 1895), p.233.
Location
Currently not on view
date made
1784
maker
Ripley, Thomas
ID Number
PH.290534
catalog number
290534
accession number
59652

Wheel Barometer

Invented in the 1660s by Robert Hooke, the "curator of experiments" in the new Royal Society of London, the “wheel” or “banjo” barometer has a tube that is bent into a J shape; a float, sitting on the shorter end of the tube, connects with a circular scale that is large and easil
Description
Invented in the 1660s by Robert Hooke, the "curator of experiments" in the new Royal Society of London, the “wheel” or “banjo” barometer has a tube that is bent into a J shape; a float, sitting on the shorter end of the tube, connects with a circular scale that is large and easily read. Barometers of this sort have long been popular for domestic use. This example is marked “D. Fagioli & Son, 39 Warner St Clerkenwell” and was made in London, perhaps in the 1840s. The dial reads from 28 to 31 inches of mercury. In addition to the barometer itself, there is a twisted gut hygrometer, a spirit thermometer, and a convex mirror. The Taylor Instrument companies gave it to the Smithsonian in 1923.
Location
Currently not on view
date made
ca 1839-1854
maker
Dominic Fagioli & Son
ID Number
PH.308173
accession number
70532
catalog number
308173

Reflecting Alidade

Sir Howard Douglas (1776-1861), a well-known military officer and author, received a British patent (#3461) for a "reflecting circle or semicircle" in 1811.
Description
Sir Howard Douglas (1776-1861), a well-known military officer and author, received a British patent (#3461) for a "reflecting circle or semicircle" in 1811. William Cary, who made the first examples of this instrument, noted that it combined a protractor with a reflecting system as used in a sextant. Cary also noted that it was "particularly useful in military survey, where the true situations of objects can at once be determined, and the sketch corrected at the same time that it is taken." Instruments of this sort were still available at the end of the 19th century.
The "Dollond London" inscription on this example refers to either George Dollond (fl. 1820-1852), or to George Dollond II (fl. 1852-1866). The horizontal arc extends 140 degrees, is graduated to 30 minutes, and is read by vernier to single minutes. The straight limb has a linear scale which is divided into tenths by diagonals. This scale is not in Imperial or metric units, and differs from that in Douglas' original instrument.
Ref: Mr. Cary, "Description of the Patent reflecting Semicircle, invented by Sir Howard Douglas, Bart," Philosophical Magazine 38 (1811): 186-187 and plate VI.
"Howard Douglas" in Dictionary of National Biography, vol. 5, pp. 1203-1206.
Location
Currently not on view
maker
Dollond, George
Dollond II, George
ID Number
PH.319452
catalog number
319452
accession number
238494

Theodolite

This theodolite was probably made in London in the mid-18th century. Its basic form-with the telescope mounted on the curved side of a semicircle-derives from the design that Thomas Heath introduced in 1725.
Description
This theodolite was probably made in London in the mid-18th century. Its basic form-with the telescope mounted on the curved side of a semicircle-derives from the design that Thomas Heath introduced in 1725. The horizontal circle and vertical arc are graduated every degree and read by verniers to 10 minutes. The words "Diff: Hypo & Base" on the telescope support and the scales labeled "Feet" and "Links" on the vertical arc are used to correlate angle of elevation or depression with horizontal distances. In addition to the telescope, there is a pair of open sight vanes. A level vial is mounted above the telescope.
This theodolite belonged to Orange Ellis, a surveyor who lived in Odelltown, a village along the Richelieu River, a few miles north of New York State. Odelltown was settled by Joseph Odell, a Loyalist from Poughkeepsie who moved from the United States to Lower Canada in 1788, in order to remain under British rule. Odelltown was later seen as a Britannic outpost in a Francophone region of Quebec.
Ref: J. A. Bennett, The Divided Circle (Oxford, 1987), pp. 86, 146-147.
Location
Currently not on view
ID Number
PH.309596
accession number
104762
catalog number
309596

Zenith Telescope

Marked "Troughton & Simms, London" and "U. S. C. S. Z. T. No 1," this is the first of four identical zenith telescopes that Troughton & Simms made for the U. S. Coast Survey.
Description
Marked "Troughton & Simms, London" and "U. S. C. S. Z. T. No 1," this is the first of four identical zenith telescopes that Troughton & Simms made for the U. S. Coast Survey. Designed for the determination of latitude by the Talcott method, the telescope arrived in the United States in 1847. In 1891 it was sent to San Francisco for use in the variation of latitude (polar motion) program organized by the International Geodetic Association. C. A Schott, the assistant in charge of the computing division of the Survey, noted at that time that this instrument was far from ideal, its "principal defect" being "a lack of stability; hence demanding great caution in handling it."
This zenith telescope was transferred to the Smithsonian in 1911. Correspondence in the accession file indicates that it was modified by William Wurdemann in 1867, and fitted with two levels in the early 1890s.
Ref: C. A. Schott, "The Variation of Latitude at San Francisco, Cal., as Determined from Observations made by George Davidson, Assistant Coast and Geodetic Survey, Between May, 1891, and August, 1892," United States Coast and Geodetic Survey Report for 1893, Appendix No. 11, p. 447.
Location
Currently not on view
date made
1840s
Associated Name
International Geodetic Association
U.S. Coast and Geodetic Survey
maker
Troughton and Simms
ID Number
PH.270200
catalog number
270200
accession number
53077

Mercury Barometer

In 1854, in the interest of safety and economy, the British Parliament authorized the establishment of a uniform system of meteorological observations at sea and the formation of a Meteorological Office within the Board of Trade.
Description
In 1854, in the interest of safety and economy, the British Parliament authorized the establishment of a uniform system of meteorological observations at sea and the formation of a Meteorological Office within the Board of Trade. Under the leadership of Vice-Admiral Robert FitzRoy, the Met Office issued a call for a barometer suitable for use by the Royal Navy. Patrick Adie got the contract, and the Kew Observatory tested each barometer before it was sent out. Matthew F. Maury, director of the U.S. Naval Observatory, reported in 1855 that he had ordered many barometers of this sort for the U.S. Navy.
This example is marked “ADIE, LONDON No 1710” and “SIGNAL SERVICE U.S. ARMY For Comparison of Barometers for International Simultaneous Meteorological Reports.” It may have been acquired by the Signal Service soon after the start of a weather service in 1870; it was last calibrated by the Weather Bureau in 1970.
Ref.: Sara Dry, “Fishermen and Forecasts: How Barometers Helped Make the Meteorological Department Safer in Victorian Britain,” Center for Analysis of Risk and Regulation Discussion Paper 46 (2007).
M.F. Maury, Explanation and Sailing Directions to Accompany the Wind and Current Charts (Philadelphia, 1855), p. 639.
Report of the Chief Signal Officer to the Secretary of War for the Fiscal Year Ending June 30, 1881, p. 1128.
Location
Currently not on view
date made
1854-1881
maker
Adie, Patrick
ID Number
PH.333822
accession number
304553
catalog number
333822

Arnold & Dent Box Chronometer

This instrument is a specialized timekeeper designed for finding longitude at sea. Its form is that of the standardized 19th-century marine chronometer. It was transferred to the Smithsonian from the U.S. Coast & Geodetic Survey.
Description
This instrument is a specialized timekeeper designed for finding longitude at sea. Its form is that of the standardized 19th-century marine chronometer. It was transferred to the Smithsonian from the U.S. Coast & Geodetic Survey. John Roger Arnold, son of chronometer maker John Arnold, and Edward John Dent (1790-1853) were in business together from 1830-1840 at 84 Strand, London. Charles Frodsham took over Arnold’s business after Arnold’s death in 1843. E. J. Dent, who had started making chronometers in 1814, continued in business until his death, when others continued the firm under various names and at various addresses. The business continues today.
Mechanism details:
Escapement: Earnshaw, spring detent
Duration: 48-hour
Power source: Spring drive with chain and fusee
Balance spring: helical, blued steel
Winding key, stamped "1131"
Bowl details:
Brass bowl, fitted with a sprung cylindrical inner bowl as a dust cover (original work); "1131" stamped on bottom inside of bowl
Dimensions: 4.17" dia. across bezel x 2.7"
Brass fittings, brass gimbal
Bezel screwed and milled
Crystal convex, plain
Dial details:
Engraved and silvered brass
Indicates hours, minutes, seconds, winding level up and down
Inscription: "ARNOLD & DENT, / 84. Strand, London No 1131”
Hands: Gold, spade, with blued steel seconds hand
Case details:
Mahogany
Three-part, glazed center section
Brass side handles and escutcheon
Bone roundel at front
Inscriptions: "1131" engraved on roundel on case. "U.S.C.S." engraved on case lid
References:
1. Gould, Rupert T. The Marine Chronometer. London: Holland Press, 1960.
2. Mercer, Tony. Chronometer Makers of the World. Essex: NAG Press, 1991.
3. Mercer, Vaudrey. John Arnold & Son. London: Antiquarian Horological Society, 1972.
4. Mercer, Vaudrey. Edward John Dent and His Successors. London: Antiquarian Horological Society, 1977.
5. Whitney, Marvin E. The Ship's Chronometer. Cincinnati: American Watchmakers Institute Press, 1985.
Location
Currently not on view
date made
1839
manufacturer
Arnold & Dent
ID Number
ME.314612
catalog number
314612
accession number
206050

Sextant

This sextant belonged to Bowdoin College in Brunswick, Maine. The frame is brass. The silvered scale is graduated every 10 minutes from -5° to +160° and read by vernier with tangent screw and swinging magnifier to 10 seconds of arc. The serial number is 1170. The "A.
Description
This sextant belonged to Bowdoin College in Brunswick, Maine. The frame is brass. The silvered scale is graduated every 10 minutes from -5° to +160° and read by vernier with tangent screw and swinging magnifier to 10 seconds of arc. The serial number is 1170. The "A. Cairns, 12 Waterloo Rd Liverpool" inscription probably refers to Alexander Cairns, an instrument dealer working in Liverpool, England during the third quarter of the 19th century.
Location
Currently not on view
date made
1855-1880
maker
Cairns, Alexander
ID Number
PH.329725
accession number
278336
catalog number
329725

Sextant

The double-framed brass sextant was patented by Edward Troughton in London in 1788, and the form remained popular throughout the first half of the 19th century.
Description
The double-framed brass sextant was patented by Edward Troughton in London in 1788, and the form remained popular throughout the first half of the 19th century. This example belonged to Haverford College in Pennsylvania and may have been acquired when that school was founded in 1833. It has a silvered scale that is graduated every 10 minutes from -5° to +145° and read by vernier with tangent screw and swinging magnifier. The inscription reads "W. & S. Jones Holborn London."
Ref: Edward Troughton, "Framing to be used in the construction of octants, sextants, and quadrants," British patent #1644.
Location
Currently not on view
date made
1800-1850
maker
W. & S. Jones
ID Number
1981.0745.06
catalog number
1981.0745.06
accession number
1981.0745

Thermometer

This mercury-in-glass thermometer has a bend in the tube just above the bulb, a milk-white back, and a scale that extends from 15 to 50 degrees Fahrenheit, graduated in fifths. The tube is marked “J.
Description
This mercury-in-glass thermometer has a bend in the tube just above the bulb, a milk-white back, and a scale that extends from 15 to 50 degrees Fahrenheit, graduated in fifths. The tube is marked “J. HICKS LONDON” and “1052.” The surrounding cylindrical case is made of wood and brass. It is marked “J. HICKS, 8, 9, & 20 HATTON GARDEN, LONDON,” and “M/O” (the mark of the British Meteorological Office), and “KEEP IN WATER TWO MINUTES.” The upper end of the case has a ring, presumably for suspending the thermometer. The lower end has a spring, presumably for protecting against shocks. This must have been made after 1884 when Hicks expanded his business into these premises, and before he merged his business with Stanley & Co. It came to the Smithsonian from the U.S. Weather Bureau.
Location
Currently not on view
date made
1884-1911
maker
J. J. Hicks
Hicks, J.
ID Number
PH.314557
catalog number
314557
accession number
204612

Box Sextant

A box (or pocket) sextant works like a traditional sextant, but here the mechanism is enclosed in a brass box of about 3 inches diameter.
Description
A box (or pocket) sextant works like a traditional sextant, but here the mechanism is enclosed in a brass box of about 3 inches diameter. William Jones, a leading instrument maker in London, introduced the form in 1797.
This example has a silvered scale that is graduated every 30 minutes from -3° to +148° and read by vernier with swinging magnifier to single minutes of arc. The "Gilbert & Sons, London" inscription above the magnifier refers to a Navigation Warehouse in London that flourished from 1806 to 1819.
Ref: William Jones, "Description of a New Pocket Box Sextant," in George Adams, Geometrical and Graphical Essays, 2nd ed. by William Jones, (London, 1797), pp. 283-285.
Location
Currently not on view
date made
early 19th century
maker
Gilbert and Sons
ID Number
PH.318442
accession number
234476
catalog number
318442

Theodolite

This is a typical English theodolite from the middle years of the nineteenth century, with an inscription that reads: Edwd Davis, Leeds."Currently not on view
Description
This is a typical English theodolite from the middle years of the nineteenth century, with an inscription that reads: Edwd Davis, Leeds."
Location
Currently not on view
date made
ca. 1850
ID Number
PH.329793
accession number
286914
286914
catalog number
329793

Aneroid Barometer

This is a cylindrical instrument, 5.5 inches in diameter. The silvered face is marked “SIGNAL SERVICE U.S. ARMY / L.
Description
This is a cylindrical instrument, 5.5 inches in diameter. The silvered face is marked “SIGNAL SERVICE U.S. ARMY / L. CASELLA / MAKER TO THE ADMIRALTY & ORDNANCE / LONDON / COMPENSATED / 2634 / ‘FOR ISSUE’ / NO 21.” The scale around the circumference of the face extends from 17 to 22 inches of mercury, graduated in tenths; another scale indicates altitudes from below 10,000 to above 15,000 feet.
This was probably made after 1870 when the Signal Service was charged with organizing a national weather service. And it was probably made before the establishment of the U.S. Weather Bureau, as a civilian agency, in 1890.
Location
Currently not on view
date made
circa 1856-1897
circa 1870-1897
1870 - 1890
maker
L. P. Casella
ID Number
PH.314547
accession number
204612
catalog number
314547

Bubble Sextant

Marine sextant with a bubble level on the frame, and "Sewill. Maker to the Royal Navy. Liverpool" and "Hezzanith/___?__ Tangent Screw / Static Clamp / No.
Description
Marine sextant with a bubble level on the frame, and "Sewill. Maker to the Royal Navy. Liverpool" and "Hezzanith/___?__ Tangent Screw / Static Clamp / No. 17840" inscriptions.
This was used by the Royal Air Force, probably during World War I, examined at the Hezzanith Observatory in London in 1919, purchased from a hock shop in San Francisco in 1923, and donated to the Smithsonian in 1994.
Heath & Co. was an English firm that began making nautical instruments in 1835, adopted the Hezzanith trademark, and was still in business in the 1960s. The Sewill firm, established in Liverpool in 1835 and still in business in the 1990s, specialized in chronometers.
This design resembles that of Heath's "Mark IV.E Patent 'Curve-Bar' Sextant." The frame is brass. The silvered scale is graduated every 10 minutes from -5° to +155° and read by vernier with tangent screw and swinging magnifier to 10 seconds of arc. A quick-release mechanism at the end of the arm engages with worm teeth cut on the underside of the limb. This mechanism, marked "‘HEZZANITH’ ENDLESS TANGENT SCREW AUTOMATIC CLAMP PATENT No. 17840," is designed to facilitate coarse adjustments. George Wilson Heath and Heath and Company, Ltd., both of Crayford, in Kent County, England, obtained a British patent for this feature in 1909. This sextant has two telescopes--one of high power and narrow field of view; the other of low power and wide field of view--as well as a pair of binoculars.
Ref: G. W. Heath and Heath & Co., "Improvements in Devices for the Adjustments of Sextants and other like Instruments," British patent #17,840.
Heath & Co., Catalogue (London, 1921-1922), p. 506.
Location
Currently not on view
date made
ca 1918
maker
Sewill
ID Number
1994.0048.01
catalog number
1994.0048.01
accession number
1994.0048

Sextant

This sextant has a brass frame. The silvered scale is graduated every 10 minutes from -5° to +145° and read by vernier with tangent screw and swinging magnifier to single minutes of arc.
Description
This sextant has a brass frame. The silvered scale is graduated every 10 minutes from -5° to +145° and read by vernier with tangent screw and swinging magnifier to single minutes of arc. The inscriptions read "Frodsham, Liverpool" and "2602." It came from Vassar College, and may have been used by the professor of astronomy, Maria Mitchell.
Ref: Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London, 1995), p. 106.
Location
Currently not on view
date made
ca 1865
maker
Charles Frodsham
ID Number
1980.0318.03
catalog number
1980.0318.03
accession number
1980.0318

Reflecting Circle

This incomplete Borda-type reflecting circle belonged to Augustana College in Rock Island, Illinois, and may have been acquired when that school was established in 1860. The inscription reads "J. & I. Hardy, London."Currently not on view
Description
This incomplete Borda-type reflecting circle belonged to Augustana College in Rock Island, Illinois, and may have been acquired when that school was established in 1860. The inscription reads "J. & I. Hardy, London."
Location
Currently not on view
date made
nineteenth century
maker
J. & I. Hardy
ID Number
1987.0196.04
catalog number
1987.0196.04
accession number
1987.0196

Dip Circle

The Department of Terrestrial Magnetism of the Carnegie Institution of Washington bought this Kew pattern dip circle in 1919.
Description
The Department of Terrestrial Magnetism of the Carnegie Institution of Washington bought this Kew pattern dip circle in 1919. The inscription reads "Dover, Charlton Kent, Circle 240." With four needles, tripod, case, Kew certificate of examination, and importation charges, it cost $184.70. The vertical circle is silvered, graduated to 30 minutes, and read by opposite verniers to single minutes. The horizontal circle is silvered, graduated to 30 minutes, and read by vernier to single minutes.
Location
Currently not on view
Date made
ca 1919
maker
Dover
ID Number
1983.0039.02
accession number
1983.0039
catalog number
1983.0039.02

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.