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.

Topic: Navigation

Telescope (Spyglass)

This telescope was probably made after 1878 when the U.S. Coast Survey became the U.S. Coast & Geodetic Survey, and was transferred to the Smithsonian in 1929. The inscription reads "L. CASELLA LONDON" and "U.S.C.&G.S. No.
Description
This telescope was probably made after 1878 when the U.S. Coast Survey became the U.S. Coast & Geodetic Survey, and was transferred to the Smithsonian in 1929. The inscription reads "L. CASELLA LONDON" and "U.S.C.&G.S. No. 168."
Casella described this as a "Military or Target Telescope" that "will show the time by a clock at six miles distance, and the form of the rocks of Calais from Dover, a distance of twenty-one miles." It has an achromatic objective, and a tapered four-draw brass body covered with leather. Its four-element erecting eye piece is "pancratic," which means that it can produce various magnifications (in this case, of 20, 25, or 30 times).
Louis Paschal Casella (1812–1897) was an Italian immigrant who opened a shop in London in 1848, offering a wide range of meteorological, mathematical, optical, and philosophical instruments, and photographic apparatus. Casella prospered, and soon obtained appointments to the Prince of Wales and several government agencies. With Charles Frederick Casella in charge, the firm became C.F. Casella in 1897, and C. F. Casella & Company Ltd. in 1910.
Ref: L. Casella, List with Notes of Standard Meteorological and Other Instruments for Observatories, Travellers and Explorers, and the Army and Navy (London, 187?), p. 61.
Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London, 1995), pp. 51-52.
Location
Currently not on view
maker
Casella, Louis Paschal
ID Number
PH.309649
catalog number
309649
accession number
106954

Sextant

Sextant with a brass frame. The silvered scale is graduated every 10 minutes from -5° to +125° and read by vernier with tangent screw and swinging magnifier to 10 seconds. The "Spencer Browning & Co. London" inscription refers to a firm that was in business from 1840 to 1870.
Description
Sextant with a brass frame. The silvered scale is graduated every 10 minutes from -5° to +125° and read by vernier with tangent screw and swinging magnifier to 10 seconds. The "Spencer Browning & Co. London" inscription refers to a firm that was in business from 1840 to 1870. The serial number is "5861."
Location
Currently not on view
date made
1840-1870
maker
Spencer, Browning & Co.
ID Number
PH.328887
accession number
277637
catalog number
328887

Sextant

Carl Philipp Heinrich Pistor (1778-1845) was an employee of the Prussian Postal Service who, having learned about optics and precision mechanics, opened an instrument workshop in Berlin in 1813, and went into partnership with his son-in-law, Carl Otto Albrecht Martins (1816-1871)
Description
Carl Philipp Heinrich Pistor (1778-1845) was an employee of the Prussian Postal Service who, having learned about optics and precision mechanics, opened an instrument workshop in Berlin in 1813, and went into partnership with his son-in-law, Carl Otto Albrecht Martins (1816-1871) in 1841. Pistor & Martins remained in business until the early 1870s, specializing in large instruments for positional astronomy. Pistor & Martins instruments in the United States include the meridian circle at the University of Michigan (1854) and the meridian circle at the U.S. Naval Observatory (1865). American also bought several prismatic sextants based on Martins’ Prussian patent of 1843—a patent describing sextants and reflecting circles with a rectangular prism in place of the horizon glass found on ordinary instruments.
These bits and pieces are is all that remain of the prismatic sextant that was ordered in 1871 by Edward S. Holden, a recent graduate of the U.S. Military Academy who was then teaching math to cadets at West Point. In 1873, when the prismatic sextant arrived from Germany, Holden was working as an astronomer at the U.S. Naval Observatory. In 1877 Holden sold it to Charles A. Young for the new John C. Green Astronomical Observatory at Princeton University, noting that it had cost him $198.50. The frame is brass. The silvered scale is graduated every 10 minutes from -10° (actually numbered 350) to +255° and read by vernier with tangent screw and magnifier. The arc is inscribed "PISTOR & MARTINS BERLIN" and "802."
Ref: Elias Loomis, Practical Astronomy (New York, 1855), pp. 101-102.
Charles A. Young papers, Princeton University Archives.
Location
Currently not on view
date made
1840-1873
1870
1871
maker
Pistor & Martins
ID Number
1983.0245.02
catalog number
1983.0245.02
accession number
1983.0245

Octant

Octant with an ebony frame and reinforced brass index arm. The brass scale is graduated every 20 minutes from -2° to +100° and read by vernier and tangent screw to single minutes of arc.
Description
Octant with an ebony frame and reinforced brass index arm. The brass scale is graduated every 20 minutes from -2° to +100° and read by vernier and tangent screw to single minutes of arc. The "Richard Patten New York" inscription refers to Richard Patten (1792-1865), an instrument maker who began in business in New York City in 1813 and was soon the proprietor of a Navigation Warehouse. By 1820 he was advertising that he was a "manufacturer of mathematical instruments . . . equal to any in the City of London." Elsewhere he claimed to be the "only manufacturer of Sextans [sic] and Quadrants in New York," and that "All instruments in the above line [are] made to order & warranted, being divided on an engine after the Plan of Ramsden’s."
Ref: Deborah J. Warner, "Richard Patten (1792-1865)," Rittenhouse 6 (1989): 57-63.
Location
Currently not on view
maker
Patten, Richard
ID Number
1993.0187.01
catalog number
1993.0187.01
accession number
1993.0187

Sextant

Ebbco began making inexpensive plastic sextants for emergency or educational use in the 1960s. In this example, the arc is graduated every degree from -10° to 120° and read by micrometer with vernier to 12 seconds.
Description
Ebbco began making inexpensive plastic sextants for emergency or educational use in the 1960s. In this example, the arc is graduated every degree from -10° to 120° and read by micrometer with vernier to 12 seconds. The inscription reads "Ebbco" and "EAST BERKS BOAT CO., ENGLAND."
Ref: J. P. G. Weatherlake, The Ebbco Sextant. Its Use, Care and Adjustment (n.p., n.d.).
Location
Currently not on view
date made
ca 1965
maker
East Berks Boat Co.
ID Number
2004.0196.01
catalog number
2004.0196.01
accession number
2004.0196

Sextant

William A. Davis was an Englishman who settled in San Leandro, California, and offered a range of inexpensive plastic nautical instruments for boating enthusiasts. He introduced the Mark III sextant in 1963, and the instrument is still in production.
Description
William A. Davis was an Englishman who settled in San Leandro, California, and offered a range of inexpensive plastic nautical instruments for boating enthusiasts. He introduced the Mark III sextant in 1963, and the instrument is still in production. Like the sextant that Cruver made for the U.S. Maritime Commission during the war, the Mark III is made of polystyrene. It has a simple eye tube, and a scale that is graduated every degree from -35° to +100° and read by vernier to 2 minutes of arc. The original Mark III cost $9.95. This example was probably made in the late 1960s. The sextant's arm is inscribed "DAVIS INSTRUMENTS CORP. / 857 THORNTON STREET / SAN LEANDRO / CALIF. 94577 / U.S.A."
Ref: William A. Davis, How to Find Your Position with a Sextant (San Leandro, 1966 and 1968).
Location
Currently not on view
maker
Davis Instruments Corporation
ID Number
2003.0331.01
catalog number
2003.0331.01
accession number
2003.0331

Octant

Octant with an ebony frame and reinforced brass index arm. The ivory scale is graduated every 20 minutes from -2° to +104° and read by vernier (without tangent screw) to single minutes of arc. A note written by Capt. H. Flynn of Lowell, Ma.
Description
Octant with an ebony frame and reinforced brass index arm. The ivory scale is graduated every 20 minutes from -2° to +104° and read by vernier (without tangent screw) to single minutes of arc. A note written by Capt. H. Flynn of Lowell, Ma. in 1891 traces the history of this octant back to 1772. Stylistic concerns suggest that the instrument was made somewhat later.
Location
Currently not on view
ID Number
PH.326933
catalog number
326933
accession number
264083

Battenberg's Course Indicator

This mechanical device, designed to solve problems involving the relative velocities of two ships at sea, was invented in 1902 by Louis Battenberg in England. The inscriptions read "Battenberg’s Course Indicator U.S. Navy Mark II" and "F.A./J.Q.M.
Description
This mechanical device, designed to solve problems involving the relative velocities of two ships at sea, was invented in 1902 by Louis Battenberg in England. The inscriptions read "Battenberg’s Course Indicator U.S. Navy Mark II" and "F.A./J.Q.M. 1924."
Born in the Prussian province of Hesse-Nassau, Louis Battenberg (1854-1921) became a British citizen in 1868 and a cadet in the Royal Navy. He rose quickly through the ranks, becoming eventually Commander-in-Chief of the Atlantic Fleet, Admiral, and then First Sea Lord. He changed his name to Mountbatten in 1917 and relinquished his German title in favor of a British one.
Ref: Gloria Clifton and Peter Ifland, "A Slice of History: The Battenberg Course Indicator," Navigation News (December 2000): 14-15.
F. S. Miller and A. F. Everett, Instructions for the Use of Martin’s Mooring Board and Battenberg’s Course Indicator (Published by Authority of the Lords Commissioners of the Admiralty, 1903).
Location
Currently not on view
maker
Battenberg, Louis
ID Number
1991.0446.02
catalog number
1991.0446.02
accession number
1991.0446

Liquid Compass

The Ritchie ledgers, now held by Ritchie Navigation, indicate that this compass was manufactured on August 11, 1877, and sold to T.S. & J.D. Negus, a New York firm that sold a variety of nautical and optical instruments. It later belonged to the U.S. Coast & Geodetic Survey.
Description
The Ritchie ledgers, now held by Ritchie Navigation, indicate that this compass was manufactured on August 11, 1877, and sold to T.S. & J.D. Negus, a New York firm that sold a variety of nautical and optical instruments. It later belonged to the U.S. Coast & Geodetic Survey. The inscriptions read "RITCHIE BOSTON U.S.A." and "PATENTED APL. 7. 1863. APL. 10, 1866. MAY 12, 1868. JULY 19, 1870" and "9786."
Ref: E. S. Ritchie & Sons, Ritchie’s Liquid Compasses and Nautical Instruments (ca. 1905).
Location
Currently not on view
date made
1877
maker
Ritchie
ID Number
PH.337138
catalog number
337138
accession number
1979.0361

Octant

Octant with an ebony frame, reinforced brass index arm, and ivory name plate. The ivory scale is graduated every 20 minutes from -3° to +109°, and read by vernier with tangent screw to single minutes of arc. The inscription reads "W.
Description
Octant with an ebony frame, reinforced brass index arm, and ivory name plate. The ivory scale is graduated every 20 minutes from -3° to +109°, and read by vernier with tangent screw to single minutes of arc. The inscription reads "W. DESILVA* LIVERPOOL."
The original wooden box (now lost) had a trade label that read "William Desilva, 78 Regent Road opposite the Bramley-Moore Hotel, Liverpool." Desilva was in business from 1851 to 1881, offering optical and nautical instruments.
The Smithsonian bought this octant in 1903 from Elias Heidenheimer (1833-1926), a German Jew who emigrated to the United in 1859, and worked as jeweler and pawnbroker in Washington, D.C. and Alexandria, Va.
Location
Currently not on view
date made
mid 19th century
maker
Desilva, William
ID Number
PH.220176
catalog number
220176
accession number
41038

Sextant

Like the "Mate" sextant made by Henry Hughes & Son, Ltd., of London, this one has a blackened brass frame, and a brass scale that is graduated every degree from -5° to +135° and read by drum micrometer to 30 minutes of arc.
Description
Like the "Mate" sextant made by Henry Hughes & Son, Ltd., of London, this one has a blackened brass frame, and a brass scale that is graduated every degree from -5° to +135° and read by drum micrometer to 30 minutes of arc. It was examined at the National Physical Laboratory at Teddington, England, in 1942.
The inscription reads "MADE IN ENGLAND FOR KELVIN & WILFRID O. WHITE Co. BOSTON & NEW YORK" and "PATENT APPLIED FOR" and "1775" and "DS&S." The DS&S insignia refers to David Shackman & Sons, the British firm that actually made this sextant. The referenced patent (GB556034), issued to Albert Shackman and Reuben Cyril Shackman in September 1943, describes details of the drum micrometer.
Ref: Kelvin & Wilfrid O. White Co., Nautical Instruments (Boston, 1940), p. 31.
Henry Hughes & Son, Ltd., Husun Navigational Instruments (London, 1939), p. 31.
M. V. Brewington, The Peabody Museum Collection of Navigating Instruments (Salem, 1963), p. 132.
Location
Currently not on view
date made
ca 1942
dealer
Kelvin & Wilfrid O. White
maker
David Shackman & Sons
ID Number
PH.337006
catalog number
337006
accession number
1978.2282

Reflecting Circle

This reflecting circle belonged to Georgetown University in Washington, D.C. and may have been purchased when Georgetown built an astronomical observatory in the early 1840s. It is of the "English" form designed by Edward Troughton in 1796.
Description
This reflecting circle belonged to Georgetown University in Washington, D.C. and may have been purchased when Georgetown built an astronomical observatory in the early 1840s. It is of the "English" form designed by Edward Troughton in 1796. Here the telescope, mirror, and filters are on one side of the circle, while the silver scale is on the other side. This scale is graduated to 20 minutes, and read by three verniers (one has a micrometer screw) to 20 seconds. The circle is supported on a heavy brass stand with a counterweight. The inscription reads "W. & S. Jones, 30 Holborn, London."
Ref: Abraham Rees, The Cyclopaedia; or, Universal Dictionary of Arts, Sciences, and Literature (London, 1819), vol. 8, art. "Circle," and Plate III of "Astronomical Instruments."
Location
Currently not on view
date made
ca 1845
maker
W. & S. Jones
ID Number
PH.328403
catalog number
328403
accession number
272470

Sextant

The "J. Allan, Baltimore" inscription on this sextant is that of John Allen (b. 1786), an "optician and mathematical instrument maker" listed in Baltimore city directories from 1810 to 1819. He was the son of James Allen, a noted instrument maker in London.
Description
The "J. Allan, Baltimore" inscription on this sextant is that of John Allen (b. 1786), an "optician and mathematical instrument maker" listed in Baltimore city directories from 1810 to 1819. He was the son of James Allen, a noted instrument maker in London. And he boasted: "As all Instruments sold by me are graduated by my father’s improved self-correcting engine, for which the Society of Arts voted him their Gold Medal, on the 19th of May, 1810–they are warranted and will be kept in repair one year, gratis."
This sextant has a brass frame. The silvered scale is graduated every 20 minutes from -5° to +145° and read by vernier with tangent screw and magnifier to 30 seconds of arc.
Ref: Deborah J. Warner, "American Octants and Sextants: The Early Years," Rittenhouse 3 (1989): 86-112, on 89.
John Allen advertisement in the American & Commercial Daily Advertiser (June 12, 1816).
Location
Currently not on view
date made
1810-1819
maker
Allen, John
ID Number
PH.326932
accession number
264083
catalog number
326932

Azimuth Mirror

William Thomson described a new "Marine Azimuth Mirror" at the 1877 meeting of the British Association for the Advancement of Science, and patented the design in Britain and the U.S.This instrument is an example of the improved design, with a reflecting prism in place of the orig
Description
William Thomson described a new "Marine Azimuth Mirror" at the 1877 meeting of the British Association for the Advancement of Science, and patented the design in Britain and the U.S.
This instrument is an example of the improved design, with a reflecting prism in place of the original mirror, that Thomson introduced in the early 1880s. It was made before 1892 when Thomson became Lord Kelvin. The inscriptions read "J. WHITE GLASGOW" and "SIR W THOMSON’S PATENT No 2673." The U.S. Naval Observatory transferred it to the Smithsonian in 1966.
Ref: William Thomson, "Device for Taking Azimuths," U.S. Patent #210,068.
William Thomson, "Azimuth Instrument," U.S. Patent #402,364.
Location
Currently not on view
patentee
Thomson, William
maker
White, James
ID Number
PH.336602
catalog number
336602
accession number
283654

Sextant

This type of sextant was introduced during World War II. The limb is graduated to single degrees. A drum micrometer, the teeth of which mesh with teeth cut into the edge of the limb, reads to 1 minute and, with vernier, to 6 seconds of arc. The inscriptions read "David White Co.
Description
This type of sextant was introduced during World War II. The limb is graduated to single degrees. A drum micrometer, the teeth of which mesh with teeth cut into the edge of the limb, reads to 1 minute and, with vernier, to 6 seconds of arc. The inscriptions read "David White Co. Milwaukee, Wis." and "U.S. NAVY, BU. NAV. MARK II"
Ref: Benjamin Dutton, Navigation and Nautical Astronomy (Annapolis, Md., 1948), pp. 347-355.
Location
Currently not on view
date made
1941-1945
maker
David White Co.
ID Number
2004.0054.01
catalog number
2004.0054.01
accession number
2004.0054

Sextant

Short discussions of the sextant began appearing in physics texts in the 1880s, and inexpensive sextants suitable for pedagogical purposes followed soon thereafter. This die-cast metal instrument is of that sort.
Description
Short discussions of the sextant began appearing in physics texts in the 1880s, and inexpensive sextants suitable for pedagogical purposes followed soon thereafter. This die-cast metal instrument is of that sort. Welch catalogs describe it as a "convenient demonstration model of an engineer’s or a mariner’s sextant." The scale is graduated every 30' from 0° to 120° and read by vernier to six minutes of arc. A small bubble level is mounted on the sighting tube. The inscription reads "W. M. WELCH SCIENTIFIC COMPANY (/) WELCH (/) ESTABLISHED 1880 (/) 1515 SEDGWICK ST. CHICAGO. U.S.A."
Ref: W. M. Welch Scientific Company, Catalog. Scientific Apparatus (Chicago, 1929-1963).
W. M. Welch Scientific Company, "Instructions for the Use of No. 3536 Sextant Model."
Location
Currently not on view
date made
ca 1929-1963
maker
Welch Scientific Company
ID Number
2004.0197.01
catalog number
2004.0197.01
accession number
2004.0197

Course Indicator

The inscription on this instrument reads "BAIN & AINSLEY’S ‘HA-HY’ COURSE CORRECTOR PAT. NO 2345 SOLD BY A. DOBBIE & SON LTD GLASGOW & SO SHIELDS." A label in the box reads "Thos. L. Ainsley, James Street, Cardiff. HEATH & COY., Limited, Crawford, Kent." A tag reads "H.M.S.
Description
The inscription on this instrument reads "BAIN & AINSLEY’S ‘HA-HY’ COURSE CORRECTOR PAT. NO 2345 SOLD BY A. DOBBIE & SON LTD GLASGOW & SO SHIELDS." A label in the box reads "Thos. L. Ainsley, James Street, Cardiff. HEATH & COY., Limited, Crawford, Kent." A tag reads "H.M.S. ADMIRALTY SERVICE."
A. Dobbie & Son, Ltd., were in business from 1896 to 1903, offering chronometers and other instruments for nautical use.
Ref: Ref: “Bain & Ainsley’s ‘HA-HY’ Course Corrector,” The Marine Engineer (May 1, 1895): 62.
T. N. Clarke, A. D. Morrison-Low, and A. D. C. Simpson, Brass & Glass. Scientific Instrument Making Workshops in Scotland (National Museums of Scotland, 1989), pp. 228-234.
Location
Currently not on view
date made
ca 1900
maker
Dobie, James
ID Number
PH.337211
catalog number
337211
accession number
1979.0825

Bamberg Liquid Compass

Carl Bamberg (1847-1892) served an apprenticeship with Carl Zeiss at Jena and studied at the Universities of Jena and Berlin before establishing a "Werkstätten für Präzisions-Mechanik und Optik" in Friedenau, a suburb of Berlin, in 1871.
Description
Carl Bamberg (1847-1892) served an apprenticeship with Carl Zeiss at Jena and studied at the Universities of Jena and Berlin before establishing a "Werkstätten für Präzisions-Mechanik und Optik" in Friedenau, a suburb of Berlin, in 1871. After Bamberg's death, the firm was managed by his widow, and then by his son. Bamberg merged with the Centralwerkstatte Dessau in 1921, forming a new company known as Askania Werke.
The inscription on this compass reads "CARL BAMBERG No 34717 BERLIN-FRIEDENAU GES. GESOH." and "Carl Bamberg Berlin-Friedenau 1915 Kaiserl Marine."
Ref: F. M. Feldhaus, Carl Bamberg, Ein Rückblick auf sein Wirken und auf die Feinmechanik (Berlin-Friedenau, 1929), p. 73.
Location
Currently not on view
date made
1915
maker
Bamberg
ID Number
PH.337139
catalog number
337139
accession number
1979.0361

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 10 seconds 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 10 seconds of arc. The "Spencer Browning & Rust LONDON" inscription on the arc refers to a firm that was in business from 1784 to 1840.
Location
Currently not on view
date made
1800-1840
maker
Spencer Browning & Rust
ID Number
1981.0943.01
catalog number
1981.0943.01
accession number
1981.0943

Sextant

Sextant with a silvered scale graduated every 10 minutes from -5° to +155° and read by vernier with tangent screw and swinging magnifier to 10 seconds. The inscription reads "E. & G. W.
Description
Sextant with a silvered scale graduated every 10 minutes from -5° to +155° and read by vernier with tangent screw and swinging magnifier to 10 seconds. The inscription reads "E. & G. W. Blunt, New York." Theodorus Bailey Myers Mason (1848-1899), a career naval officer, probably acquired this sextant in 1865 when he graduated from the Naval Academy at Newport, R.I. Mason's sister Cassie (Mrs. Julian) James, a Washington socialite, gave it to the Smithsonian.
Location
Currently not on view
date made
1856-1866
user
Mason, Theodorus B. M.
maker
E. & G. W. Blunt
ID Number
PH.275100
catalog number
275100
accession number
70138

Ritchie Liquid Compass

This compass–with six needles, and a flat card with central buoyancy–was Ritchie’s most successful design and was widely used by American merchant ships and the U.S. Navy. The Ritchie ledgers, now held by Ritchie Navigation, indicate that this example was manufactured on Jan.
Description
This compass–with six needles, and a flat card with central buoyancy–was Ritchie’s most successful design and was widely used by American merchant ships and the U.S. Navy. The Ritchie ledgers, now held by Ritchie Navigation, indicate that this example was manufactured on Jan. 5, 1873 and sold to one L. J. Sloane. The U.S. Coast & Geodetic Survey acquired it in 1914, and transferred it to the Smithsonian in 1929. The inscriptions read "E. S. RITCHIE BOSTON. PATENTED SEPT. 9, 1862. APL. 7, 1863. MAY 12, 1868. July 19, 1870" and "6937" and "U.S.C.&G.S."
Ritchie’s patent of Sept. 9, 1862 (#36,422) described a liquid compass so designed that the liquid would not oxidize the magnet or card, and that the friction and wear of the pivot and its bearing was minimized. Ritchie obtained two patents on April 7, 1863. One (#38,125) described a needle enclosed in an air-tight metallic case; the other (#38,126) described a liquid compass that could be read at a distance so it would not be affected by any iron on or about the deck of a ship. Ritchie’s patent of May 12, 1868 (#77,763) described a paint that would not deteriorate in the liquid in the compass. His patent of July 19, 1870 (#105,492) described a way to hold the glass in place with a water-tight joint..
Ref: E. S. Ritchie & Sons, Ritchie’s Liquid Compasses and Nautical Instruments (ca. 1905).
T. S. & J. D. Negus, Illustrated Catalogue of Nautical Instruments (New York, n.d.), p. 204.
Location
Currently not on view
date made
1873
maker
Ritchie, Edward S.
ID Number
PH.309656
catalog number
309656
accession number
106954

St. John Dry Card Compass

John Ransome St. John designed a mariner’s compass that would determine local changes in magnetic variation.
Description
John Ransome St. John designed a mariner’s compass that would determine local changes in magnetic variation. Although the instrument was complex and largely useless, it garnered a gold medal at the American Institute fair of 1849; a Prize Medal at the Crystal Palace exhibition held in London in 1851; and an English patent (#8785) in 1852.
The inscriptions on this example read "JOHN R. ST JOHN. Inventor-Buffalo, N.Y. U.S.A. 1843" and "Lith. of E. Jones & G. W. Newman" and "128 Fulton St New York."
Ref: "John R. St. John’s Variation Compass and Velocimeter," Transactions of the American Institute (1851): 204-205.
Location
Currently not on view
date made
ca 1850
patentee
St. John, John R.
ID Number
PH.314744
catalog number
314744
accession number
210834

Octant

Octant with an ebony frame, flat brass index arm, and ivory scale and name plate. The scale is graduated every 20 minutes from -3° to +99° and read by vernier with top-mounted tangent screw to single minutes of arc.
Description
Octant with an ebony frame, flat brass index arm, and ivory scale and name plate. The scale is graduated every 20 minutes from -3° to +99° and read by vernier with top-mounted tangent screw to single minutes of arc. The inscription reads "HARRIS & Co Holborn London." This octant probably dates from the first half of the 19th century when there were several men of this name working at this address, making and marketing mathematical and optical instruments.
Ref: Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London, 1995), pp. 124-126.
Location
Currently not on view
maker
Harris & Co.
ID Number
PH.329726
catalog number
329726
accession number
278336

Telescope

This telescope was probably made around 1900, and It probably belonged to Llewellyn N. Edwards (1874-1952), a structural engineer. It has an achromatic objective, and a tapered four-draw brass body covered with leather.
Description
This telescope was probably made around 1900, and It probably belonged to Llewellyn N. Edwards (1874-1952), a structural engineer. It has an achromatic objective, and a tapered four-draw brass body covered with leather. Its four-element pancratic eye piece produces erect images with magnifications of 25, 30, 35 or 40 times. The inscription reads "BROADHURST. CLARKSON & CO / 63 FARRINGDON ROAD / LONDON, E.C."
Ref: Broadhurst, Clarkson & Co., Portable Telescopes (London, n.d.)
Location
Currently not on view
date made
ca 1900
maker
Broadhurst, Clarkson & Co.
ID Number
PH.333802
catalog number
333802
accession number
296611

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