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This ivory instrument has two rectangular arms with flat edges and is held together by 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 is held together by 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 80 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 40 degrees; log sine, running from 1 to 70 degrees; and logarithmic, running from 2 to 10 and then from 1 to 10. A double line separates these scales from the inner, diagonal set of scales. The top face of the instrument has a scale of equal parts that runs from 90 to 10. There is no maker's mark.; 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 scales for dialing typically found on English-style sectors are not present. Spanning both arms on the outer edge is a scale of inches, running from 11 to 1 and divided to tenths of an inch. The sector likely dates to the mid-19th century. Compare to MA.335351, MA.333937, and MA.321755.; The donor kept this object and 1985.0580.01 in a blue cardboard box that originally held 12 Eldorado 4H no. 2 pencils made by the Joseph Dixon Crucible Company of Jersey City, N.J. Dixon sold this brand from 1917 to the mid-1950s.; Reference: Dennis B. Smith, "Wood Cased Drafting Pencils," Leadholder: The Drafting Pencil Museum, http://leadholder.com/wood-dixon-eldorado.html.
Location: Currently not on view

date made: 19th century

ID Number: 1985.0580.06
catalog number: 333931
accession number: 1985.0580

By the mid-20th century, printing adding machines with a block of ten keys sold much more cheaply than full-keyboard machines. Mindful that it was losing sales, Burroughs Adding Machine Company of Detroit set out to manufacture its own ten-key machine.

Description: By the mid-20th century, printing adding machines with a block of ten keys sold much more cheaply than full-keyboard machines. Mindful that it was losing sales, Burroughs Adding Machine Company of Detroit set out to manufacture its own ten-key machine. The Burroughs Patent Division acquired examples and blueprints of a recently introduced British adding machine, the Summit.; This manually operated example of the Summit has a steel case painted gray, a block of 12 number keys (for the 12 digits in Sterling currency), four keys on the right, and a “COR” key on the left. The metal crank on the right has a wooden handle. A place indicator is above the keyboard. The machine allows one to enter numbers up to nine digits long and prints nine-digit totals. The printing mechanism with paper tape is at the back. The paper tape is 6 cm. (2-3/8”) wide, with a serrated edge for tearing it off. A metal plate at the top lifts off for access to the mechanism and the black ribbon. The machine has wheels on the left and the right to advance the platen.; The machine is marked on the front: Summit. It is also marked there: MADE IN GREAT BRITAIN. It has serial number: #1885. A red Burroughs Patent Department tag attached to the machine reads: #300.; Compare to 1982.0794.77.
Location: Currently not on view

date made: 1950

ID Number: 1982.0794.76
maker number: #1885
accession number: 1982.0794
catalog number: 1982.0794.76

This spectroscope has a collimator with slit, a viewing telescope, and a brass stand with iron trileg base. One quarter of the horizontal circle is graduated to 20’ and read by vernier. The original prism has been lost.

Description: This spectroscope has a collimator with slit, a viewing telescope, and a brass stand with iron trileg base. One quarter of the horizontal circle is graduated to 20’ and read by vernier. The original prism has been lost. The “John Browning 63 Strand, London” inscription on the circle refers to John Browning (ca. 1831-1925), the first important English spectroscope maker. Browning moved to that address in 1872, sold his firm in 1900, and termed this a Student’s Spectroscope.; The “J. W. Queen & Co. PHILADELPHIA” inscription on a tag refers to an American firm that was selling Browning instruments by 1874.; This came from Baldwin-Wallace University in Berea, Ohio, but whether it was originally owned by the Baldwin Institute or the German Wallace College is not yet known.; Ref: John Browning, How to Work with the Spectroscope (London, 1878), p. 14.; James W. Queen & Co., Illustrated Catalogue of Instruments Used in Physical Optics (Philadelphia, 1888), p. 57.
Location: Currently not on view

date made: ca 1870-1890

maker: Browning, John

ID Number: 1985.0386.04
accession number: 1985.0386
catalog number: 85.386.4

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

This brass drawing instrument consists of a narrow 10" arm joined to a base (4-1/8" by 1-1/16") with a thumbscrew. The arm may be placed in two positions: horizontally and at 150° (30° if measuring an angle opening to the right).

Description: This brass drawing instrument consists of a narrow 10" arm joined to a base (4-1/8" by 1-1/16") with a thumbscrew. The arm may be placed in two positions: horizontally and at 150° (30° if measuring an angle opening to the right). Since it only measures 30° angles, this device is an isometric protractor. An isometric protractor is used to create three-dimensional drawings by depicting an object from an angle at which the scales on the three axes are equal. The technique was popular in the 19th century for its simplicity and ease of use. In the 20th century, isometric projections were typically created on specialized graph paper marked with triangles. In the 21st century, isometric engineering drawings and the isometric protractors used to prepare them are both created with computers.; The base of this protractor is engraved with a presentation mark: TO (/) Alexander Leslie C. E. (/) FROM (/) Mortimer Evans. Leslie (1844–1893) was a civil engineer who was especially known for constructing waterworks in Scotland. From 1871, he partnered with his father, James Leslie (1801–1889), in Edinburgh. James was the nephew of the mathematician John Leslie. He trained under the architect William H. Playfair and worked with George and John (Jr.) Rennie early in his career. He was a founding member of the British Institution of Civil Engineers. Alexander was elected to the society in 1869. In 1871, he was elected to the British Association for the Advancement of Science, while Mortimer Evans became a member of that institution in 1876. Little is known of Evans or of when and why he presented this isometric protractor to Leslie. Evans lived in Glasgow in the 1870s and then moved to the Piccadilly area of London, where he patented a precursor of a motion picture camera (with William Friese-Greene) in 1889.; The protractor is stored in a leather case lined with blue satin and blue velvet. The lid of the case has a protrusion to accommodate the thumbscrew.; References: William Farish, "On Isometrical Perspective," Transactions of the Cambridge Philosophical Society 1 (1822); William Ford Stanley, Mathematical Drawing and Measuring Instruments, 6th ed. (London, 1888), 268; Catalog of Eugene Dietzgen Co., 12th ed. (Chicago, 1926), 41, 44; Institution of Civil Engineers, "Alexander Leslie," Minutes of the Proceedings 116 (1894): 366–368.
Location: Currently not on view

date made: ca 1870

recipient: Leslie, Alexander
producer: Evans, Mortimer

ID Number: 1983.0474.01
accession number: 1983.0474
catalog number: 1983.0474.01

In 1851 Scottish civil engineer John Sang (1809–1887) exhibited a form of rolling planimeter at the Crystal Palace Exhibition in London.

Description: In 1851 Scottish civil engineer John Sang (1809–1887) exhibited a form of rolling planimeter at the Crystal Palace Exhibition in London. He called the instrument a "planometer," which he changed to "platometer" when he described the instrument to the Royal Scottish Society of Arts a few months later. Like all planimeters, this object measures the area bounded by a closed curve. Sang's device is also significant because it inspired James Clerk Maxwell to work on planimeters, which in turn gave James and William Thomson ideas that helped them develop a mechanical integrator.; This example is an improved version of Sang's original instrument. A brass cone is on a steel rod that connects two brass rollers. An open brass frame surrounds the rod. It has four brass rollers that slide along a brass base to which the rod is anchored. The frame has a tracer with an ivory handle, a silver measuring wheel that rolls against the side of the cone, and a small magnifying glass. The handle on the tracer arm and the construction of the measuring wheel are changed from Sang's original design.; The measuring wheel rotates only when the tracer arm's movement is perpendicular to the axis of the cone. The rate at which the wheel moves depends on its distance from the vertex of the cone. For example, when the tracer arm moves a distance S perpendicular to the axis, its reading changes by an amount equal to the area of a rectangle with sides equal to S times the distance from the vertex. The instrument is in a wooden case.; This object was received at the Smithsonian in 1983.; References: John Sang, "Description of a Platometer, an Instrument for Measuring the Areas of Figures Drawn on Paper," Transactions of the Royal Scottish Society of Arts 4 (1852): 119–129; "Description of Sang's Platometer, or Self-Acting Calculator of Surface," Journal of the Franklin Institute 23 (1852): 238–241; Charles Care, "Illustrating the History of the Planimeter" (Undergraduate 3rd Year Project, University of Warwick, 2004), 39–44; Charles Care, "A Chronology of Analogue Computing," The Rutherford Journal 2 (2006–2007), http://www.rutherfordjournal.org/article020106.html.
Location: Currently not on view

date made: 1850s

maker: Sang, John

ID Number: 1983.0474.02
accession number: 1983.0474
catalog number: 1983.0474.02

This instrument is in the shape of a hollow octagonal prism. A pair of dividers (measuring 10.6 x 1.3 x 1.2 cm) screws into one end. One leg of the dividers may be removed and placed in a hole at the other end of the scale.

Description: This instrument is in the shape of a hollow octagonal prism. A pair of dividers (measuring 10.6 x 1.3 x 1.2 cm) screws into one end. One leg of the dividers may be removed and placed in a hole at the other end of the scale. A slide then moves the leg back and forth for use as a scriber.; A scale appears on each face of the instrument: inches (divided to 1/10" and numbered from 1 to 6); chords; sines; tangents; equal parts of 30, 25, and 20 to the inch; and "calibre." Many of these scales appeared on sectors; like those instruments, this object would have been used for surveying, architectural drawing, and artillery positioning.; The face with the calibre scale is marked: G. Adams LONDON. In 1734, George Adams Sr. (1709–1772) established a workshop on Fleet Street. From 1756 the firm fulfilled hundreds of commissions as instrument maker to His Majesty's Office of Ordnance. George Adams Jr. (1750–1795) took over the business after his father's death, with help from his mother, Ann, for the first couple of years. Although he retained the ordnance commissions, these became less profitable over time and the firm was in debt when he died. George Jr.'s wife, Hannah, sold the remaining stock and tools in 1796. Father and son both used the signature "G. Adams," so this instrument cannot be dated precisely.; References: Gloria Clifton, Directory of British Scientific Instrument Makers 1550–1851 (London: National Maritime Museum, 1995), 2–3; John R. Millburn, Adams of Fleet Street: Instrument Makers to King George III (Burlington, Vt.: Ashgate, 2000); Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/.
Location: Currently not on view

date made: ca 1750–1795

maker: Adams, George

ID Number: 1987.0379.01
accession number: 1987.0379
catalog number: 1987.0379.01

This brass universal equinoctial ring dial consists of a meridian ring, hour ring, rotating crosspiece or bridge, and sliding handle with suspension ring.

Description: This brass universal equinoctial ring dial consists of a meridian ring, hour ring, rotating crosspiece or bridge, and sliding handle with suspension ring. The meridian ring is calibrated from 0 to 90 by degree on one side (for solar altitude) and from 0 to 90 x 2 by degree on the opposite side (for northern altitudes). There is a fleur de lis at each 5-degree mark. The hour ring is calibrated from I to XII x 2 by I on one side. There is a set of three dots at each 15- and 45-minute mark and a fleur de lis at each half-hour. The divisions continue onto the inner edge of the hour ring. There is some decoration at each end of the bridge. The bridge contains a pinhole gnomon which slides along a calendar scale calibrated and lettered by month on one side. The opposite side contains the maker's mark and a declination scale calibrated from 20 to 0 to 20. Ten units on this scale measure 1.5 cm. Both sides of the meridian ring and the opposite side of the hour ring are engraved with a list of twenty-one European cities and Constantinople with latitudes. Twelve of the cities are in England.; Henry Winne (or Wynne) was a well-known London instrument maker of the second half of the 17th century who sold to Gregory, Flamsteed, and Hooke.
Location: Currently not on view

maker: Henry Winne

ID Number: 1987.0851.01
catalog number: MA*326974; 326974
accession number: 1987.0851

This pamphlet folds out to eight pages and was printed on light green paper by Carbic Limited, the British manufacturer of Otis King's Pocket Calculator, a cylindrical slide rule.

Description: This pamphlet folds out to eight pages and was printed on light green paper by Carbic Limited, the British manufacturer of Otis King's Pocket Calculator, a cylindrical slide rule. Carbic's address on the pamphlet—171, Seymour Place, London, W.I.—is scratched out and reprinted as 54, Dundonald Road, London, S.W.19. Dundonald Road was the last known location for Carbic, and the company was there by 1959. The calculator was available by mail order in 1960 for 62s. 6d. (roughly $175.00).; The pamphlet provides details of the scales on the Model K (which performed multiplication and division) and the Model L (which also provided readings of logarithms for determining roots and powers). The examples also include problems of proportion, percentages, constant factors, and calculations in pounds sterling (before decimalization of British currency). The last three pages provide instructions for operating the instrument.; See also 1987.0788.01 and 1987.0788.07.; Reference: "Finding the Answer is Simplicity Itself," advertisement for the Otis King Pocket Calculator, The New Scientist 5, no. 121 (March 12, 1959): 548 and 8, no. 213 (December 15, 1960): 1568.
Location: Currently not on view

date made: ca 1960-1962

maker: Carbic Limited

ID Number: 1987.0788.06
accession number: 1987.0788
catalog number: 1987.0788.06

This 21" German silver hinged parallel rule has two small knobs for positioning the instrument. Brass round pieces cover the screws securing the two hinges. An indentation is on both blades at the center of the rule, with a line marking the center.

Description: This 21" German silver hinged parallel rule has two small knobs for positioning the instrument. Brass round pieces cover the screws securing the two hinges. An indentation is on both blades at the center of the rule, with a line marking the center. The edges of the top blade are marked as a rectangular protractor, and the edges of the bottom blade are marked for nautical compass points.; The center of the top blade is marked: U. S. C. & G. S. NO. 331. The right end of the top blade is marked: CAPT. FIELD'S IMP^D. The right end of the lower blade is marked: H. HUGHES & SON L^TD. LONDON. The left end has the firm's "HUSUN" logo, with a sun above the letters and waves below the letters.; Capt. William Andrew Field (about 1796–1871) of Britain added a protractor and compass scales to hinged parallel rules in 1854. This made it easier for ship navigators to move the rule without losing track of the ship's course. Henry Hughes & Son made marine and aeronautical navigational instruments in London from 1828 to 1947 and incorporated in 1903. According to the accession file, the U.S. Coast & Geodetic Survey acquired this rule on August 21, 1919, and last issued it on September 5, 1922. Compare to MA.309662 and MA.309663.; References: "Field's Parallel Rule," The Nautical Magazine and Naval Chronicle 23, no. 5 (May 1854): 280; Peggy A. Kidwell, "American Parallel Rules: Invention on the Fringes of Industry," Rittenhouse 10, no. 39 (1996): 90–96; National Maritime Museum, "Captain Field's Improved Parallel Rule," Object ID NAV0602, http://collections.rmg.co.uk/collections/objects/42814.html; Science Museum Group, "Henry Hughes and Son Limited," Collections Online – People, http://collectionsonline.nmsi.ac.uk/detail.php?type=related&kv=58792&t=people.
Location: Currently not on view

date made: 1919

ID Number: MA.309661
catalog number: 309661
accession number: 106954

This pocket-sized wooden case is covered with black shagreen, leather made from the skin of a shark or rayfish. On the paper lining the inside of the lid, a previous owner has written: N. O'CONNOR 2/12/1806.

Description: This pocket-sized wooden case is covered with black shagreen, leather made from the skin of a shark or rayfish. On the paper lining the inside of the lid, a previous owner has written: N. O'CONNOR 2/12/1806. Ten drawing instruments were received with the case:; 1) A 4-1/2" boxwood plotting scale with diagonal scales at each end. Above the plotting scale are scales divided to 0.12" and to 1/10". The other side has a scale of chords and architect's scales dividing the inch into 35, 30, 25, 20, 15, and 10 parts.; 2) A 6" ebony parallel ruler with scalloped brass hinges.; 3) A pair of 3-3/4" brass and steel fixed-point dividers.; 4) A pair of 6-1/4" brass and steel dividers with a removable point.; 5) A brass and steel pen point that fits the 6-1/4" dividers.; 6) A pair of 5-14" brass and steel fixed-point dividers.; 7) A 3" brass and steel drawing pen with a swiveling handle.; 8) A lead pencil.; 9) A metal joint tightener and file.; 10) A brass gauge, unevenly graduated from 100 to 1,000 and marked "16 FT" on one side and unevenly graduated from 1,000 to 150 and marked "C 8 FT 6 IN" on the other. The first side is also marked: NEWTON & Co 3 FLEET S^T NEAR TEMPLE BAR LONDON.; William and Frederick Newton were the partners of Newton & Company, which sold scientific instruments and lantern slides from 3 Fleet Street in London from 1851 until the 1930s, when the firm moved to Wigmore Street. In the 1950s, the company was renamed Newton Photographic Services Ltd. The gauge, joint tightener, and pencil likely date to the mid-19th century. The other instruments are consistent with the 1806 date written on the case.; The donor, civil engineer C. B. Beyer of Albuquerque, New Mexico, gave the instruments to the Smithsonian in 1953.; References: Science Museum Group, "Collections Online – People," http://collectionsonline.nmsi.ac.uk/detail.php?type=related&kv=43411&t=people; Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London: National Maritime Museum, 1995), 200.
Location: Currently not on view

date made: 1806

maker: Newton & Co.

ID Number: MA.314286
catalog number: 314286
accession number: 199264

This ivory rectangular protractor is three times larger in area than many surviving ivory rectangular protractors from the nineteenth century, which tend to be short and narrow enough to fit in a pocket.

Description: This ivory rectangular protractor is three times larger in area than many surviving ivory rectangular protractors from the nineteenth century, which tend to be short and narrow enough to fit in a pocket. (See MA.335349, MA.321754, and MA.321014.) Catalogs of the time period advertise foot-long rectangular protractors comparable to this one, but at approximately $12 each, they were 3 to 8 times as expensive as 6-inch versions. Thus, surveyors probably did not purchase and use the large protractors as often.; This protractor is graduated to half-degrees and marked by tens from 10 to 170 in both the clockwise and counterclockwise directions. The interior of the protractor contains a maker's mark: LONDON MADE. FOR MCALLISTER & CO. PHILADELPHIA. The front of the protractor also contains a diagonal scale; a scale of chords which is divided by half-degrees and marked by tens from 10 to 90; and scales for dividing 1 inch into 10, 20, and 30 parts. These scales were used to create drawings in which 1 inch represented 1, 2, and 3 feet, respectively.; A chain scale is on the bottom edge of the protractor, facing outwards (i.e., appearing upside-down as one looks at the front of the protractor). The scale is graduated to half-units and marked by ones from 1 to 44 and from 44 to 1. The numbers from 44 to 1 are called an "offset." Ten units on the scale total 1/4" in length. A surveyor's chain was 66 feet long and contained 100 links. Thus, this chain scale represented 4 links to each inch. The number 40 (described as a "line of 40" or a "scale of 40" in trade catalogs) is marked at the midpoint of the protractor, in between the chain scale and the scale dividing 1 inch into 30 parts. The markings are worn off the protractor in a few places.; The back of the protractor bears scales for dividing the inch into 80, 60, 55, 50, 45, 40, 35, and 30 parts. There are also scales for 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, and 1 inch to the foot. The protractor is stored in a black and red leather and cardboard case that is badly worn.; William Young McAllister (1812–1896) was a third-generation optician and dealer of mathematical instruments in Philadelphia. His firm was known as McAllister & Co. between 1836 and 1853. From 1830 to 1836, he partnered with his father, John McAllister Jr., and between 1853 and 1865 he partnered with his brother, Thomas, who subsequently worked as an optician in New York City. This protractor is slightly different from the 12-inch ivory protractor described in McAllister's 1867 catalog: this object is 1/4" wider; there are eleven scales of equal parts instead of ten; there are eight scales of feet and inches instead of twelve; there is one scale of chords instead of two; and there is a chain scale. John C. Armstrong of Washington, D.C., donated the protractor to the Smithsonian in 1933.; References: William Ford Stanley, Mathematical Drawing and Measuring Instruments 6th ed. (London: E. & F. N. Spon, 1888), 227–230; Catalogue of Keuffel & Esser, 33rd ed. (New York, 1909), 176; "McAllister Family Business Timeline," The John A. McAllister Collection, Library Company of Philadelphia, http://www.librarycompany.org/mcallister/pdf/McAllister%20family%20business%20timeline.pdf; A Priced and Illustrated Catalogue of Mathematical Instruments . . . Sold Wholesale and Retail by William Y. McAllister (Philadelphia, 1867), 25; Peggy A. Kidwell, "James Prentice's Rectangular Protractor," Rittenhouse 1, no. 3 (1987): 61–63.
Location: Currently not on view

date made: 1836-1853

maker: McAllister, William Young

ID Number: MA.310743
accession number: 127352
catalog number: 310743

This is the U.S. patent model for a cylindrical slide rule invented by George Fuller (1829–1907), a British civil engineer and professor of engineering at Queen's College, Belfast. Fuller received patents in Great Britain (no. 1044) in 1878 and in the United States in 1879. W.

Description: This is the U.S. patent model for a cylindrical slide rule invented by George Fuller (1829–1907), a British civil engineer and professor of engineering at Queen's College, Belfast. Fuller received patents in Great Britain (no. 1044) in 1878 and in the United States in 1879. W. F. Stanley of London manufactured the rule from 1879 until 1975, and it was marketed in the United States by Keuffel & Esser, Dietzgen, and other dealers.; The model has a wooden handle and shaft, with a wooden cylinder that slides up and down the shaft. A paper covered with scales fits around the cylinder. The lower edge of the cylinder has a scale of equal parts. The remainder bears a spiral scale divided logarithmically. A rectangular clear plastic pointer has broken from its attachment on the handle and is tucked into a red ribbon tied around the cylinder. A paper patent tag is marked: No. 291.246; 1879 (/) G. Fuller. (/) Calculators. (/) Patented Sept 2. (/) 1879. A printed description from the patent application of April 16, 1878, is glued to the back of the tag. The tag is attached to the handle with a red ribbon.; L. Leland Locke, a New York mathematics teacher and historian of mathematics, collected this patent model and intended it for the Museums of the Peaceful Arts in New York City. When that institution encountered financial difficulties in 1940, Locke gave a collection of objects, including this model, to the Smithsonian Institution.; For production models of this instrument, see 313751, 316575, and 1998.0046.01.; References: George Fuller, "Improvement in Calculators" (U.S. Patent 219,246 issued September 2, 1879); The Report of the President of Queen's College, Belfast, for the Year Ending October, 1876 (Dublin, 1877), 9, 29–30, 107–110; James J. Fenton, "Fuller's Calculating Slide-Rule," Transactions and Proceedings of the Royal Society of Victoria 22 (1886): 57–61; Dieter von Jezierski, Slide Rules: A Journey Through Three Centuries, trans. Rodger Shepherd (Mendham, N.J.: Astragal Press, 2000), 42–43.
Location: Currently not on view

date made: 1878

patentee: Fuller, George
maker: Fuller, George

ID Number: MA.311958
accession number: 155183
catalog number: 311958

This ebony ruler has ivory edges divided to 1/12" and numbered by ones from 1 to 6. Ivory rollers at each end of the ruler's interior are numbered by sixes from 6 to 18 and within brass housings.

Description: This ebony ruler has ivory edges divided to 1/12" and numbered by ones from 1 to 6. Ivory rollers at each end of the ruler's interior are numbered by sixes from 6 to 18 and within brass housings. The rollers are connected by a metal rod that runs through a brass and paper counting dial numbered by ones from 1 to 12. A metal pointer or index attached to this dial shows the number of inches the rule has rolled. The rod is covered with ebony. The right end of the rule is marked: DOLLOND (/) LONDON. A wooden case is covered with black leather and lined with green velvet.; The Dollond family began to make eyeglasses, telescopes, and scientific instruments in London in the mid-18th century. A. George Eckhardt invented a rolling parallel ruler in 1771 and gave the patent to the firm. In the late 18th century, brothers and partners Peter and John Dollond advertised four forms of parallel rulers: an ebony rule with unnumbered brass rollers; a rule adding ivory scales on the rollers; a rule adding ivory scales along the edges; and a rule adding the measuring dial with index. This object is a 6" example of the fourth type of rule and sold for 1 pound, 6 shillings. The firm merged with Aitchison & Co. in 1927 and was purchased by Boots Opticians in 2009.; References: Deborah J. Warner, “Browse by Maker: Dollond,” National Museum of American History Physical Sciences Collection: Surveying and Geodesy , http://amhistory.si.edu/surveying/maker.cfm?makerid=10; Maya Hambly, Drawing Instruments: 1580–1980 (London: Sotheby's Publications, 1988), 111–113; A Catalogue of Retail Prices of Optical, Mathematical and Philsophical Instruments made by P. and J. Dollond, Opticians to His Majesty in St. Paul's Church-Yard and St. James Haymarket (London, [1780–1805]); accession file.
Location: Currently not on view

date made: late 18th century

maker: Dollond

ID Number: MA.323499
catalog number: 323499
accession number: 250508

In the late 19th and early 20th centuries, several circular slide rules were made to resemble pocket watches. Fowler & Co., of Manchester, England, was a particularly notable manufacturer of this type of slide rule.

Description: In the late 19th and early 20th centuries, several circular slide rules were made to resemble pocket watches. Fowler & Co., of Manchester, England, was a particularly notable manufacturer of this type of slide rule. The company was in business from 1898 to 1988 and made a large variety of calculators, although the labor-intensive nature of its manufacturing process produced expensive instruments that never sold in large numbers.; This example is the "long scale" model, consisting of a metal case with a ring, two knobs, and two rotating paper discs covered with glass. The front has a short logarithmic scale and a long logarithmic scale, laid out in six concentric circles rather than in a spiral. These scales are rotated by the knob on the left. The glass is marked with two hairlines. The interior of the disc reads: FOWLER'S (/) LONG SCALE CALCULATOR (/) PATENT (/) FOWLER & Co MANCHESTER.; The other knob rotates the seven scales on the back of the instrument: multiplication and division, reciprocals, logarithms, square roots, logarithmic sines, logarithmic tangents, and a second scale for logarithmic sines. The interior is marked: FOWLER'S (/) CALCULATOR (/) PATENT (/) FOWLER & Co MANCHESTER. There is one hairline indicator on the glass. The slide rule is with a tarnished square metal case, lined with purple velvet. The outside of the case is engraved: Fowler's (/) CALCULATOR. The inside is stamped: Fowler & Co. (/) CALCULATOR (/) SPECIALISTS (/) Manchester (/) ENGLAND.; William Henry Fowler (1853–1932) and his son, Harold Fowler, took out several British patents for improvements to circular calculators between 1910 and 1924. The first Fowler calculator with two knobs on the rim was patented in 1914. In 1927, Fowler & Co. introduced the Magnum Long Scale Calculator, which extended the scale length to 50 inches. Thus, this example is dated between 1914 and 1927.; Charles Looney (1906–1987), the donor of this slide rule, catalogued engineering drawings and trade literature at the Smithsonian after he retired from the University of Maryland–College Park, where he served as chair of the Department of Civil Engineering. He also donated his library of books and pamphlets to the Museum.; References: Peter M. Hopp, "Pocket-Watch Slide Rules," Journal of the Oughtred Society 8, no. 2 (1999): 45–51; Richard Blankenhorn and Robert De Cesaris, "The Fowler Calculators: A Catalogue Raisonné," Journal of the Oughtred Society 11, no. 2 (2002): 3–11; Museum of History and Science in Manchester, "Fowler & Co.," http://www.mosi.org.uk/media/33870536/fowlerandco.pdf; accession file.
Location: Currently not on view

date made: 1914-1927

maker: Fowler & Co.

ID Number: MA.333849
catalog number: 333849
accession number: 303780

Rutherford-Geiger alpha-particle charge apparatus 1908, replica of Cavendish Lab apparatus.

Description: Rutherford-Geiger alpha-particle charge apparatus 1908, replica of Cavendish Lab apparatus. Object ID EM.N-08019: length 13 in (33.1 cm) x width 13 1/2 in (34.2 cm) x depth 1 15/16 in (4.9 cm); This object consists of a cylindrical glass body with a tapered ground socket at each end. (Cylinder axis is vertical). On each side, at the middle of the glass cylinder, a glass tube extends out horizontally. The longer of the 2 tubes is provided with a stopcock.; Into the lower ground socket of the main body is inserted a cylindrical glass vessel with a rounded bottom. A glass tube (emitter stem) extending at right angles from the inserted glass cylinder supports an axial brass rod, insulated with red wax. The end of this rod inside the vessel bears a horizontal brass ring, to which is soldered a thick wire across the diameter of the ring. At the center of this is soldered a vertical wire, at the upper end of which is a horizontal rectangular plate.; Into the upper ground socket of the main body is inserted a second cylindrical glass vessel, this one bearing an axial glass tube (collector stem) through which passes an axial brass rod, insulated at each end with red wax. The lower end of this rod bears the collecting electrode, consisting of a short hollow brass cylinder with a disc of foil, possibly aluminum, across its lower end.; History and basic principles; In 1908 the New Zealand physicist Ernest Rutherford, working at the Cavendish Laboratory in Cambridge, England, was trying to understand the so-called “alpha particle,” one constituent of the radiation given off by radioactive substances. He had earlier shown that the alpha particle had a positive charge and was heavier than the previously known electron. Rutherford suspected that it was the same as the helium atom.; To confirm this conjecture, he needed several pieces of evidence: the number of alpha particles given off in each radioactive decay, and the mass and electrical charge of the particles. Rutherford and his colleague Hans Geiger developed the apparatus shown here to collect the charge carried by the particles given off by a radioactive source in a given period of time. Separate experiments gave the rate of emission of the particles, from which the charge on a single particle could be computed.; The radioactive material was mounted as a thin film on a holder set in the lower bulb. The emitted alpha particles passed upwards (the apparatus was evacuated to eliminate absorption by air) and struck an insulated collector plate, to which they transferred their charge. The plate was connected to a sensitive external electrometer that measured the charge delivered in a given time. The charge determined was close to twice the electron charge, supporting Rutherford’s hypothesis.; Additional background on the replica of the Rutherford-Geiger alpha-particle charge apparatus; At the beginning of the 20th century, Ernest Rutherford was studying the distinct types of radiation (alpha, beta, and gamma rays) emitted from radioactive elements. In 1908 Rutherford and Hans Geiger conducted a series of experiments to determine the charge and nature of the alpha particle. Their apparatus is described in the following reference: Ernest Rutherford, Radioactive Substances and their Radiations, Cambridge: 1913, p. 135, section 61, Fig. 28. Their original paper on these particular experiments is: “The Charge and Nature of the α-Particle” by Ernest Rutherford and Hans Geiger, Proceedings of the Royal Society A., Vol. 81, 1908, pp. 162-173. (This paper is reprinted in James Chadwick, ed., The Collected Papers of Lord Rutherford of Nelson, New York, 1963, Vol. 2, pp. 109-120); Object N-08019 was made at the Cavendish Laboratory, Cambridge, England, and is a copy of the original apparatus preserved in the Museum at the Cavendish Laboratory. See Cavendish Laboratory Museum photo at:; http://www-outreach.phy.cam.ac.uk/camphy/museum/area4/images/cabinet_5.jpg; While both our replica and the original at the Cavendish Laboratory Museum resemble the Rutherford-Geiger apparatus as described in Rutherford and Geiger’s publications, they nevertheless differ in several details, as described below.; As described by Rutherford in the first of the above references, the apparatus had a short cylindrical central glass section with a ground joint at each end, into which fit closed-off glass pieces, one longer than the other. The apparatus was “exhausted to a charcoal vacuum” in order to avoid collisions of alpha particles with atoms in ambient air. Alpha particles emitted from a radioactive source in the lower of these end pieces passed up through aluminum foil mounted in the central section and were absorbed by a collector plate supported on insulators in the upper end piece. The current between the collector and the foil was measured with an electrometer. The rate of collection of alpha particles was calculated from the results of earlier experiments. These particular experiments yielded the charge on the alpha particle. Rutherford and Geiger found that each alpha particle carried a charge that was twice the “unit” charge (i.e., charge of hydrogen “atom”). They were thus able to infer that the alpha particle is an “atom” of helium.; Our replica, object N-08019, is as described by Rutherford in the above references, except that the alpha emitter consists of a brass ring on an insulated stem, with a wire across the ring, to which is soldered an axial wire bearing a rectangular plate at its upper end. And in our replica, there is no foil diaphragm across the central section, as in Rutherford’s description. The collector in our replica matches that as described by Rutherford. Further details on the differences between the Rutherford-Geiger apparatus and object N-08019 are contained in notes in the Curator’s file for this accession. The reason for these differences is not known. One possibility is that Rutherford and Geiger modified their apparatus after carrying out the experiments described in their paper.
Location: Currently not on view

date made: 1960

originator: Rutherford, Ernest
maker: University of Cambridge. Department of Physics. Cavendish Laboratory

ID Number: EM.N-08019
catalog number: N-08019
accession number: 224580

This ivory instrument has two rectangular arms with flat edges and is held together by a circular brass hinge. The scales run from top to bottom on each arm.

Description: This ivory instrument has two rectangular arms with flat edges and is held together by a circular brass hinge. The scales run from top to bottom on each arm. On one side, each arm has a sine scale, running from 10 to 80 degrees; a tangent scale, running from 50 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 45 degrees; log sine, running from 1 to 70 degrees; and logarithmic, running from 1 to 10 twice. The top face of the instrument has a scale of equal parts that divides one foot into 100 increments and runs from 90 to 10. There is no maker's mark.; 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 40 to 75 and labeled s; and a scale of chords, running from 10 to 60 and labeled C. The scales for dialing typical of 18th-century English-style sectors are not present. Spanning both arms on the outer edge is a scale of inches, running from 12 to 1 and divided to tenths of an inch. The sector likely dates to the mid-19th century. Compare to 1985.0580.06, MA.335351, and MA.321755.
Location: Currently not on view

date made: 19th century

ID Number: MA.333937
catalog number: 333937
accession number: 305959

J.J. Thomson's cathode ray tube #2, replica of Cavendish Lab apparatus. Object ID EM.N-08013-A; overall; length 30.5 cm, glass ball diam. 8.5 cm.This object consists of a glass cylindrical body with a larger diameter glass ball at one end.

Description: J.J. Thomson's cathode ray tube #2, replica of Cavendish Lab apparatus. Object ID EM.N-08013-A; overall; length 30.5 cm, glass ball diam. 8.5 cm.; This object consists of a glass cylindrical body with a larger diameter glass ball at one end. Four shorter glass tubes with internal wires extend perpendicularly from the cylinderical body (see 1st object on left in accompanying image).; Basic principle; Rays from cathode in cylinder pass through 2 metal slots and between 2 metal plates onto glass ball. Metal plates can have electric field applied across them. External magnetic field can be applied to balance electric deflection. Used to determine the ratio of charge to mass (q/m) of the electron. For theory Ref: J.J Thomson, Phil. Mag., 44 (1897) 293. For a concise review of J.J. Thomson, the Cavendish Laboratory, and Thompson's cathode ray tube and positive ray apparatus, see J .J. Thomson - the Centenary of His Discovery of the Electron and his invention of Mass Spectrometry, Rapid Communications in Mass Spectrometry, Vol.11, 2-16 (1997).; History; In the second half of the nineteenth century the phenomena accompanying the discharge of electricity through highly rarified gases received increasing attention from physicists. The development of theory and experimental technique raised expectations of insight from this quarter into the structure of the atom and the connection between matter and electricity. (See object ID EM.N-08253, Geissler tube demonstration apparatus.); In the early 1890s attention focused upon the rays which, at the highest evacuations, stream out from the negative pole (cathode) of the discharge tube and produce a fluorescent glow of its glass walls. Philip Lenard, working in Germany, greatly intensified the physicists' interest in these "cathode rays" by bringing them out of the discharge tube through a hole sealed with metal foil. (See object ID EM.N-08517, Discovery of electron display apparatus with cathode ray discharge tube.); Between 1897 and 1899 J. J. Thomson, Director of the Cavendish Laboratory, Cambridge University, produced convincing evidence that cathode rays were universal sub-atomic constituents of matter, of identical mass and electric charge. This was the discovery of the electron.; J. J. Thomson devised many discharge tubes in his study of cathode rays. The one with the greatest import, both for his research and for experimental techniques in the emergent field of atomic physics, effected the deflection of the cathode rays by electric and magnetic fields simultaneously. By this means Thomson measured the ratio of the charge to the mass of the "rays,” and established that they were particles, much lighter, and presumably much smaller, than atoms.
Location: Currently not on view

date made: ca. 1960

originator: Thomson, J. J.
manufacturer: University of Cambridge. Department of Physics. Cavendish Laboratory

ID Number: EM.N-08013-A
accession number: 224580
catalog number: N-8013-A

This brass universal equinoctial ring dial consists of a meridian ring, hour ring, rotating crosspiece or bridge, and sliding suspension ring/handle. The base of the suspension ring is marked with a vernier for the meridian ring that reads to 3 minutes of accuracy.

Description: This brass universal equinoctial ring dial consists of a meridian ring, hour ring, rotating crosspiece or bridge, and sliding suspension ring/handle. The base of the suspension ring is marked with a vernier for the meridian ring that reads to 3 minutes of accuracy. The meridian ring is calibrated on one side for northern and southern latitudes from 0 to 90 to 0 x 2 by single degree. The reverse contains an elongated nautical quadrant for solar altitude calibrated 90 to 0 by half-degree and from 0 to 90 by 10 degrees. The hour ring is calibrated from I to XII x 2 by I. The hour ring is also divided by minutes (20, 40, 60) underneath the hour marks and along the inside edge of the hour ring. The bridge contains a pinhole gnomon sliding over a calendar scale calibrated by month (in 3-letter abbreviations) and day. An engraved line on either side of the pinhole enables the user to line up the gnomon with the proper calendar day. The reverse of the bridge contains a declination scale from 20 to 0 to 20 by units of 0.5 and labeled with S.D. (south declination), AE (equinox?) and N.D. (north declination). The reverse of the bridge also contains a zodiacal sign scale divided into 30s. There is a fitted black or blue leather and wood case with green velvet lining for this instrument.; There were numerous instrument makers named Dollond, but Peter Dollond is known to have sold sundials in the late 1700s.
Location: Currently not on view

date made: late 1700s

maker: Dollond, Peter

ID Number: MA.326980
catalog number: 326980
accession number: 272472

Wilson's cloud chamber, replica of Cavendish Lab apparatus, Object ID EM.N- 08016. Overall: height 71 cm x width 35 cm x depth 35 cm.A wooden frame supports, above, a wide glass cylinder (the expansion chamber).

Description: Wilson's cloud chamber, replica of Cavendish Lab apparatus, Object ID EM.N- 08016. Overall: height 71 cm x width 35 cm x depth 35 cm.; A wooden frame supports, above, a wide glass cylinder (the expansion chamber). Extending to one side, below is a spherical glass vessel that can be evacxuated.; Components: expansion chamber; evacuated chamber; piston; inlets to pumps, to manometer, and for cooling water; and connections for residual clearing field. All supported by body of instrument and supported on wooden stand.; History and basic principle; Particle detectors are of two types: “counters” and “chambers.” The former merely signal the fact that a particle has passed through (from which signal the energy or velocity of the particle can often also be obtained). “Chambers,” however, do not merely signal a transiting charged particle, but trace its path and—most important—the paths of any other charged particles emerging from collisions which it may undergo with matter filling the chamber.; The first detector of the “chamber” type was the cloud chamber, devised in 1911 by C.T.R. Wilson at the Cavendish Laboratory, Cambridge University, England. The tracks of charged particles are rendered visible by the condensation of water vapor about the ionized air molecules (nitrogen and oxygen) produced along the paths of fast-moving charged particles. The chamber is sealed and saturated with water vapor by the water in the trough. When the valve is opened by pulling to the left, the air under the piston rushes into the evacuated bulb. The piston drops suddenly, the air in the chamber is rendered super-saturated, and droplets of water condense about any ions present. The battery produces an electric field to sweep the chamber clear of ions after each expansion.

Date made: 1961 (original 1912)
date made: 1961 (original 1912)

originator: Wilson, C. T. R.
manufacturer: University of Cambridge. Department of Physics. Cavendish Laboratory

ID Number: EM.N-08016
accession number: 224580
catalog number: EM.N-08016

This relatively late English-built arithmometer represents C. & E. Layton's improvements to the machine originally designed by Samuel Tate.

Description: This relatively late English-built arithmometer represents C. & E. Layton's improvements to the machine originally designed by Samuel Tate. The stepped drum manually operated non-printing calculating machine has a brass and steel mechanism attached in a mahogany case.; The eight setting levers are above a row of windows that show the number set. The zeroing lever for the setup is on the right and an ADD-MULT / SUB DIV lever is on the left. The crank for operating the machine is right of the levers. Below it is zeroing lever for the entry levers. The stepped drums are brass.; The carriage has 9 windows in the revolution counter register and 16 in the result register. On the right of the carriage is a crank that is turned counterclockwise to zero the revolution register and clockwise to zero the result register. When the entry in the result register would become negative (as it might in subtraction or division), a bell rings. It rings again if a number is added to bring the total to zero or more.; Decimal markers slide along rods above the entry windows, revolution register windows, and result register windows.; Handles at both ends aid in lifting the machine. The case lacks a lid. A space for a compartment is on the left side, but it has no cover.; The mark on the front of the machine reads: LAYTONS IMPROVED ARITHMOMETER (/) LONDON 1911 (/) PATENTS Nos 8984 & 12032 - 1909 BÄURLES. PATENTS Nos 1666 & 15261 - 1907. No serial number was found.; The machine is from the collection of Felt & Tarrant Manufacturing Company of Chicago.; Compare 311953, 323657, 323629, and 333922. The approximate date is taken from an existing catalog card and from the machine.; Reference:; Horsburgh, E. M., ed., Handbook of the Napier Tercentenary Celebration of Modern Instruments and Methods of Calculation, Edinburgh: G. Bell & Sons, 1914, pp. 102–104.
Location: Currently not on view

date made: 1911

maker: C. & E. Layton

ID Number: MA.323657
catalog number: 323657
accession number: 250163
maker number: none found

This pantograph has four linked brass bars with rectangular cross section. The longer bars on the outside are 26 ½ inches long, the shorter bars on the inside 13 ¼ inches long.

Description: This pantograph has four linked brass bars with rectangular cross section. The longer bars on the outside are 26 ½ inches long, the shorter bars on the inside 13 ¼ inches long. Two arms on the pantograph are marked for reducing and enlarging, both having with one scale ranging from ½ down to 1/12 and a second scale going from 11/12 down to 2/3. Once the wheels are screwed in, the pantograph slides along a table. This example has a tracer point but no pencil point and no weight. A mark on one arm reads: Cary London. It fits in a shaped wooden case.; Compare MA.317868, MA.327891, MA.334888, and 2005.0182.8.; According to Gloria Clifton, William Cary, his descendants and their associates in London sold instruments, including a pantograph, under the name Cary from 1789 until 1891.; Reference:; Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851, Zwemmer, 1995, p. 51.
Location: Currently not on view

maker: Cary, William

ID Number: MA.317868
accession number: 231764
catalog number: 317868

This yew wood and brass rule finds the number of weeks between two dates that were up to two years apart. The months of the year are listed along the right edge, from January to December, twice.

Description: This yew wood and brass rule finds the number of weeks between two dates that were up to two years apart. The months of the year are listed along the right edge, from January to December, twice. The month names are adjacent to a continuous calendar for the 24 months, with seven days per row. A brass slide to the left of the calendar is numbered from 1 to 104 (for two years of weeks). A ring at the top for hanging the rule is marked: TIME TABLE. Dock companies used the rule to compute storage charges for goods shipped to or from British ports.; The right edge is marked: DRING & FAGE MAKERS TOOLEY S^T LONDON. The English firm established by John Dring and William Fage operated at various locations on Tooley Street from 1792 to 1882. For another timetable, or rent, rule by this maker, see inventory number 1954–305 at the Science Museum in South Kensington, London, http://www.sciencemuseum.org.uk/objects/mathematics/1954-305.aspx. The Science Museum owns several dozen other objects by this maker; see http://collectionsonline.nmsi.ac.uk/detail.php?type=related&kv=2628&t=people.; The back of the rule is stenciled: HWE. The Smithsonian acquired this object in 1962. No further information on the original owner is available.; Reference: Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/.
Location: Currently not on view

date made: 1792–1882

maker: Dring & Fage

ID Number: MA.320636
catalog number: 320636
accession number: 242721

This instrument consists of a wooden base to which a flat rectangular scale printed on white celluloid is attached. The scale is divided logarithmically and arranged in 20 parallel lines. Each line is about five inches long.

Description: This instrument consists of a wooden base to which a flat rectangular scale printed on white celluloid is attached. The scale is divided logarithmically and arranged in 20 parallel lines. Each line is about five inches long. A wooden frame slides backward and forward over the base. Within this frame is a second frame, which has a clear celluloid window. Four index marks are drawn on the window. A loose metal wedge with a pin attached serves as a pointer, and it may be placed at any point on the window. The scales are marked: THE COOPER 100 INCH SLIDE RULE (/) PATENTED.; The feet of the base are lined with green felt. The instrument fits in a leather-covered cardboard box that is lined with white felt. A sticker inside the lid reads: WILLIAM DUBILIER (/) 72 Esplanade (/) NEW ROCHELLE, N. Y. There is also a note that reads: TELEPHONE, PARK 1081. (/) WIRELESS CALL, 5AU. (/) 94, ADDISON ROAD (/) KENSINGTON, W. 14. (/) 24/12/22 (/) To W. D. (/) With very best wishes for (/) Xmas and the New Year. (/) W.v.P.; William Dubilier (1888–1969), the donor of this instrument, was an American electrical engineer and inventor who received this instrument from a friend in Great Britain in 1922. By 1923, W. F. Stanley & Co. made this rule and stamped the outer frame with its mark. Although the rule worked well for multiplication and percentage problems, it was difficult to set the rule accurately for more complex calculations. At the relatively high price of £4, the instrument probably never sold widely. No patents for the device have been found. For the instruction manual, see MA.259739.01.; References: Werner H. Rudowski, "The Cooper 100-inch Slide Rule: An Update," Slide Rule Gazette 8 (Autumn 2007): 25–27; Peter M. Hopp, Slide Rules: Their History, Models, and Makers (Mendham, N.J.: Astragal Press, 1999), 116; "William Dubilier, Inventor, Is Dead," New York Times (July 27, 1969), 65; accession file.
Location: Currently not on view

date made: 1922

maker: Stanley, William Ford

ID Number: MA.326237
catalog number: 326237
accession number: 259739

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Replica of Rutherford and Geiger apparatus for determining the charge on the alph-particle, after original Cavendish Lab apparatus of 1908

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J.J. Thomson's cathode ray tube #2, replica of Cavendish Lab apparatus

Equinoctial Sundial by Peter Dollond

Wilson's cloud chamber, replica of Cavendish Lab apparatus

Layton's Improved Arithmometer

Pantograph in Case by Cary of London

Dring & Fage Timetable Sliding Rule

Cooper 100-Inch Slide Rule