Planimeters -- Polar–Coradi
Polar–Coradi
Instrument maker Gottlieb Coradi established a workshop in Zurich in 1880 and soon began making polar planimeters in the Amsler style. In 1894 he adjusted the pole arm so that it was higher than the tracer arm. He also replaced the pivot connecting the arms with a ball joint. The result, which he called a "compensating" polar planimeter, prevented errors introduced by planimeters made in the Amsler style because Coradi's instrument could trace in both the clockwise and counterclockwise directions. As the relatively large number of Coradi planimeters in the collection suggests, the instruments were widely sold in the United States in the early 20th century—even though they were somewhat more expensive than Amsler planimeters. Because the firm put a label inside each case with the exact date on which each planimeter was manufactured, along with the specific calibration for each instrument, it is easy to identify Coradi planimeters and arrange them in chronological order.
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Coradi Polar Planimeter
- Description
- This instrument has two arms. The German silver tracer arm has a support for the tracer point and is evenly divided by tenths numbered from 10 to 37. Ten units are equivalent to 5mm. The tracer arm fits within a carriage of brass, painted black, that also holds a white plastic measuring wheel and vernier and a metal registering dial. The pole arm is made of brass painted black and is attached to the carriage. The end of the pole arm fits into a rectangular metal weight faced with brass painted black. The weight is marked: G. Coradi Zürich (/) No 759. The bottom of the weight is covered with paper. A cylindrical brass weight fits into a hole on top of the pole arm. The testing rule is missing.
- A wooden case covered with black leather is lined with purple velvet. A paper printed chart glued inside the lid has columns in German for Scales, Position of the vernier on the tracer bar, Value of the unit of the vernier on the measuring roller, and Constant. The values are handwritten. The date on the chart indicates the Coradi firm made serial number 759 on December 28, 1888.
- Gottlieb Coradi (1847–1929) established a workshop in Zurich in 1880 and began making wheel and disc polar planimeters in the Amsler style soon thereafter. In 1894, he modified the design into the "compensating" polar planimeter; see MA*321777. Union College donated this instrument in 1964.
- Reference: "People: Gottlieb Coradi," Waywiser, Harvard University Department of the History of Science, http://dssmhi1.fas.harvard.edu/emuseumdev/code/eMuseum.asp?lang=EN.
- Location
- Currently not on view
- date made
- 1888
- maker
- Coradi, Gottlieb
- ID Number
- MA.323707
- catalog number
- 323707
- accession number
- 252804
- Data Source
- National Museum of American History, Kenneth E. Behring Center
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Coradi Model 30 Rolling Sphere Planimeter
- Description
- This planimeter can measure larger diagrams than planimeters with a fixed arm, and it is designed to eliminate errors introduced by irregularities in the paper. It moves on two German silver rollers. The roller on the left rotates a steel wheel that in turn rotates an axle that turns the measuring wheel and registering dial. The measuring wheel has a vernier. All three parts are made of white plastic. The ten-inch rectangular German silver tracer arm is attached to a carriage below the measuring wheel and between the rollers. It has a brass tracer with steel point and support. The length of the arm is adjustable, and it is evenly divided to 0.5mm and numbered from 10 to 54. An extension for the tracer arm adds eight inches to its length and is numbered from 55 to 88.
- Above the roller on the right is marked: G. Coradi, Zürich (/) Switzerland (/) No 1550. An oblong German silver testing rule is marked for 0", 1", 2", 3", and 4". It is also marked: G. Coradi. A fitted wooden case is covered with black leather and lined with purple velvet. The brush that goes in the corner of the case is missing. A paper printed calibration chart glued inside the lid has columns in French for Scales, Position of the vernier on the tracer bar, Value of the unit of the vernier on the measuring roller, and Constant. The values are handwritten, and the Constant column is crossed out. A paragraph explains how to store the instrument. The date on the chart indicates the Coradi firm made serial number 1,550 on November 2, 1901. A separate card has the chart values translated into English. According to a 1915 catalog, Coradi sold this size of planimeter as model 30.
- The top of the case is marked: MU 3412. The key for the case is tied to the handle with string. A metal circle on the bottom of the case is marked: WEBCO. The Zurich workshop of Gottlieb Coradi (1847–1929) made a variety of planimeters beginning in the early 1880s, with the rolling sphere form debuting around 1900. The Department of Civil Engineering at the University of Missouri-Columbia donated this example in 1972. Although when and where the department acquired it is not known, American firms such as Keuffel & Esser and Dietzgen distributed Coradi's precision disc planimeter. K&E sold this size before 1901 as model 1106 and from 1901 to 1936 as model 4260, charging $82.50 in 1900. Dietzgen only sold a larger version that had twelve-inch and eight-inch tracer arm pieces. Compare to 1977.0112.01. A later instruction manual is 1977.0112.02. For other objects from the Univ. of Missouri's donation, see MA*333663 and MA*333636.
- References: J. W. Beardsley, "Description and Theory of Coradi's Rolling Ball Planimeter," Journal of the Association of Engineering Societies 28 (1902): 67–77; J. Y. Wheatley, The Polar Planimeter and Its Use in Engineering Calculations (New York: Keuffel & Esser, 1903), chapter 10, http://www.leinweb.com/snackbar/planimtr/wheatley/s10-6.htm; Clark McCoy, "Collection of Pages from K&E Catalogs for the 4260 Family of Precision Rolling Planimeters," http://www.mccoys-kecatalogs.com/PlanimeterModels/ke4260family.htm; Catalogue of Keuffel & Esser, 30th ed. (New York, 1900), 308; Catalogue & Price List of Eugene Dietzgen Co., 7th ed. (Chicago, 1904), 363; Mathematical-Mechanical Institute of G. Coradi, Catalogue of Mathematical Precision Instruments (Zurich, 1915), 13–17.
- Location
- Currently not on view
- date made
- 1901
- maker
- Coradi, Gottlieb
- ID Number
- MA.333660
- catalog number
- 333660
- accession number
- 300659
- Data Source
- National Museum of American History, Kenneth E. Behring Center
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Instruction Manual for Coradi Planimeters
- Description
- The citation information for this 40-page booklet is: G. Coradi, The Coradi Planimeters: Description and Instructions for the Use and Testing, with a General Elementary Explanation of Their Operation (Zurich, 1912). Gottlieb Coradi (1847–1929) established a workshop in Zurich in 1880 and began making wheel and disc polar planimeters in the Amsler style soon thereafter. In 1894, he designed the compensating polar planimeter, and by 1900, his firm was selling a precision rolling planimeter.
- This booklet explains the mathematical theory behind planimeters, which are used to measure the area bounded by a curved diagram. Coradi then describes the general parts of a planimeter and provides instructions for the forms manufactured by his workshop: the rolling sphere planimeter (see MA*333660 and 1977.0112.01), the precision disc planimeter (see MA*321745), and the compensating polar planimeter (see 1987.0929.01 and MA*321777). Olaus Henrici (1840–1918), a German mathematician who taught at English universities, helped Coradi prepare the booklet.
- The donor also provided three Coradi pamphlets on the coordinatograph, an instrument for quickly plotting points on a map according to their rectangular coordinates. According to the illustrations at the back of this booklet, Coradi's firm also made integraphs and pantographs.
- References: "People: Gottlieb Coradi," Waywiser, Harvard University Department of the History of Science, http://dssmhi1.fas.harvard.edu/emuseumdev/code/eMuseum.asp?lang=EN; Olaus Henrici, "On Planimeters," in Report of the Sixty-fourth Meeting of the British Association for the Advancement of Science (London, 1894), 496–523.
- Location
- Currently not on view
- date made
- 1912
- maker
- Coradi, Gottlieb
- ID Number
- 1977.0112.02
- accession number
- 1977.0112
- catalog number
- 1977.0112.02
- Data Source
- National Museum of American History, Kenneth E. Behring Center
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Coradi Adjustable Polar Compensating Planimeter Sold by Eugene Dietzgen (Model 6612)
- Description
- This instrument has two arms. Made of German silver, the first arm is 9" long, and has a brass and steel tracer point with a support. The arm is evenly divided into tenths and numbered from 5 to 38. (One unit is equivalent to 5mm.) It fits into a brass carriage painted black that has a white plastic measuring wheel, vernier, and registering dial. Screws on the carriage adjust the length of the tracer arm. The carriage is marked: No 20495.
- A 9" German silver pole arm fits into a hole in the carriage. Near that end, the arm is evenly divided into tenths and numbered from 30 to 34. The arm fits inside a sliding rectangular tube made of brass painted black (i.e., "bronzed brass"). A cylindrical brass weight is attached to the end of the tube. The tube is marked: G. Coradi, Zürich Switzerland D.P.G.M. Eugene Dietzgen Co. An oblong steel testing plate is marked for 0", 1", 2", and 3". It is also marked: G. Coradi Zürich.
- A wooden case is covered with black leather and lined with green velvet. A printed paper chart is pasted inside the case. The chart has columns for Scales, Position of the vernier on the tracer bar, Value of the unit of the vernier on the measuring roller, and Length of the pole-arm for the constant 20,000. The values in the Position and Length columns are handwritten in the same hand that indicates the Coradi firm manufactured this planimeter with serial number 20,495 on January 18, 1913. The date and serial number indicate that this instrument was manufactured before MA*321777. 1977.0112.02 is an instruction manual.
- Gottlieb Coradi (1847–1929) began to make wheel and disc polar planimeters in the early 1880s. In 1894, he made the pole arm higher than the tracer arm and connected the arms with a ball joint. This "compensating" planimeter could trace in both the clockwise and counterclockwise directions, preventing errors introduced by planimeters made in the Amsler style. The Eugene Dietzgen Company of Chicago sold Coradi's compensating planimeter from at least 1905 to at least 1931. The version with the adjustable pole arm cost $47.00, which was $11.00 more than the standard version. The model number was changed from 6612 to 1806 between 1910 and 1926. Keuffel & Esser also sold the instrument from 1901 to 1939.
- References: "The Lang-Coradi Planimeter," in Olaus Henrici, "On Planimeters," in Report of the Sixty-fourth Meeting of the British Association for the Advancement of Science (London, 1894), 496–523, on 515; Catalogue & Price List of Eugene Dietzgen Co., 7th ed. (Chicago, 1904), 362; Catalogue & Price List of Eugene Dietzgen Co., 9th ed. (Chicago, 1910), 503; Catalogue & Price List of Eugene Dietzgen Co., 12th ed. (Chicago, 1926), 183; Catalogue & Price List of Eugene Dietzgen Co., 14th ed. (Chicago, 1931), 205; Clark McCoy, "Collection of Pages from K&E Catalogs for the 4240 Family of Polar Planimeters," http://www.mccoys-kecatalogs.com/PlanimeterModels/ke4240family.htm.
- Location
- Currently not on view
- date made
- 1913
- distributor
- Eugene Dietzgen Company
- maker
- Coradi, Gottlieb
- ID Number
- 1987.0929.01
- accession number
- 1987.0929
- catalog number
- 1987.0929.01
- Data Source
- National Museum of American History, Kenneth E. Behring Center
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Coradi Compensating Polar Planimeter Sold by Keuffel & Esser (Model 4240)
- Description
- This instrument has two arms. The first arm is 9" long. Made of German silver, it has a brass and steel tracer point. The arm is evenly divided into tenths and numbered from 5 to 38. It fits into a brass carriage, painted black, which also holds a white plastic measuring wheel, vernier, and registering dial. Screws on the carriage adjust the length of the tracer arm. The carriage is marked: No 22241.
- An 8" brass (painted black) pole arm fits into a hole in the carriage. A cylindrical brass weight is attached to the other end. The arm is marked: G. Coradi, Zürich Switzerland Keuffel & Esser Co New York. An oblong steel testing plate is marked for 0", 1", 2", and 3". It is also marked: G. Coradi Zürich.
- A wooden case covered with black leather is lined with purple velvet. A printed paper chart is pasted inside the case. The chart has columns for Scales, Position of the vernier on the tracer bar, Value of the unit of the vernier on the measuring roller, and Constant. The values in the Position and Constant columns are handwritten in the same hand that indicates the Coradi firm manufactured this planimeter with serial number 22,241 on July 15, 1914. Keuffel & Esser stamped the chart with its model number, 4240.
- Gottlieb Coradi (1847–1929) began to make wheel and disc polar planimeters in the early 1880s. In 1894 he made the pole arm higher than the tracer arm and connected the arms with a ball joint. This "compensating" planimeter could trace in both the clockwise and counterclockwise directions, preventing errors introduced by planimeters made in the Amsler style. In 1901 K&E began selling Coradi's compensating planimeter for $36.00. In 1936 the firm began offering the planimeter under the company's Paragon brand name and charged $49.00. K&E stopped selling the instrument in 1939. The Interstate Commerce Commission transferred this example to the Smithsonian in 1963. ID number 1977.0112.02 is an instruction manual.
- References: Peggy Aldrich Kidwell, "Planimeter," in Instruments of Science: An Historical Encyclopedia, ed. Robert Bud and Deborah Jean Warner (London: Garland Publishing, 1998), 467–469; "The Lang-Coradi Planimeter," in Olaus Henrici, "On Planimeters," in Report of the Sixty-fourth Meeting of the British Association for the Advancement of Science (London, 1894), 496–523, on 515; Clark McCoy, "Collection of Pages from K&E Catalogs for the 4240 Family of Polar Planimeters," http://www.mccoys-kecatalogs.com/PlanimeterModels/ke4240family.htm; Catalogue of Keuffel & Esser, 33rd ed. (New York, 1909), 323; Catalogue of Keuffel & Esser, 38th ed. (New York, 1936), 256.
- Location
- Currently not on view
- date made
- 1914
- distributor
- Keuffel & Esser Co.
- maker
- Coradi, Gottlieb
- ID Number
- MA.321777
- catalog number
- 321777
- accession number
- 246883
- Data Source
- National Museum of American History, Kenneth E. Behring Center
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Coradi Precision Disc Polar Planimeter
- Description
- This polar planimeter has a German silver tracer arm that is evenly divided to half-millimeters and numbered from 8 to 66. (One unit is equivalent to 5mm.) The tracer point is bronzed brass and steel and has a support. The length of the tracer arm may be adjusted by thumbscrews on a bronzed brass carriage. A hinged horizontal extension from the carriage holds a white plastic vernier, measuring wheel, and registering dial. The wheel rests on a black-coated aluminum disc faced with white paper. The wheel and disc both rotate when the tracer point is moved. The disc regulates the motion of the wheel, so that it is not affected by folds or other uneven points in the paper with the diagram to be traced.
- A bronzed brass holder for the disc is marked: G. Coradi. Zürich. Switzerland (/) No 4012. The holder rests in the middle of a round brass weight that is 6" in diameter. An oblong German silver testing rule is marked for 0", 1", 2", and 3". It is also marked: G. Coradi Zürich. An oblong brass testing rule is marked for inches and for 0, 50, and 100mm. It is also marked: G. Coradi Zürich.
- A wooden case covered with black morocco leather is lined with purple velvet. A printed paper chart is pasted inside the case. The chart has columns for Scales, Position of the vernier on the tracer bar, Value of the unit of the vernier on the measuring roller, and Constant. The values in the Position and Constant columns are handwritten in the same hand that indicates the Coradi firm manufactured this planimeter with serial number 4,012 on March 25, 1916.
- Gottlieb Coradi (1847–1929) began to make wheel and disc polar planimeters in the early 1880s. The Interstate Commerce Commission transferred this instrument to the Smithsonian in 1962. There is no record of where the ICC purchased the planimeter, but American firms such as Keuffel & Esser (1906–1936 as model 4251) and Dietzgen (by 1926, as model 1808) distributed Coradi's precision disc planimeter. K&E sold it for $95.00 in 1906, for $85.00 in 1909 and, by special order, for $215.00 in 1936. Dietzgen charged $127.00 in 1926. ID number 1977.0112.02 is an instruction manual.
- References: Clark McCoy, "Collection of Pages from K&E Catalogs for the 4251 Family of Precision Polar Disc Planimeters," http://www.mccoys-kecatalogs.com/PlanimeterModels/ke4251family.htm; Catalogue of Keuffel & Esser, 32nd ed. (New York, 1906), 336; Catalogue of Keuffel & Esser, 33rd ed. (New York, 1909), 324; Catalogue of Keuffel & Esser, 38th ed. (New York, 1936), 343; Catalogue & Price List of Eugene Dietzgen Co., 12th ed. (Chicago, 1926), 183.
- Location
- Currently not on view
- date made
- 1916
- maker
- Coradi, Gottlieb
- ID Number
- MA.321745
- catalog number
- 321745
- accession number
- 246883
- Data Source
- National Museum of American History, Kenneth E. Behring Center
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Coradi Polar Compensating Planimeter Sold by Keuffel & Esser (Model 4242)
- Description
- The adjustable tracer arm on this German silver and bronzed brass instrument is evenly divided to tenths of a unit, with each unit equal to 5mm, and numbered from 5 to 36. The measuring wheel, vernier, and registering dial are white plastic. A second vernier is made of German silver and used with the scale on the tracer arm. The carriage for the measuring wheel is marked: No 25743. The pole arm fits inside a tube attached to a cylindrical weight, allowing the arm's length to be adjusted. The pole arm has a scale like the scale on the tracer arm, but it is numbered from 30 to 34. The tube is marked: G. Coradi, Zürich Switzerland.
- An oblong German silver testing rule is marked for 0", 1", 2", and 3". It is also marked: G. Coradi Zürich. A wooden case covered with black morocco leather is lined with purple velvet. A printed paper chart is pasted inside the case. The chart has columns for Scales, Position of the vernier on the tracer bar, Value of the unit of the vernier on the measuring roller, and Constant. The values in the Position and Constant columns are handwritten in the same hand that indicates the Coradi firm manufactured this planimeter with serial number 25,748 in 1917.
- The label is also stamped in purple: 4242. This was the model number used by Keuffel & Esser of New York, which sold the instrument from 1901 to 1972. The price was $46.50 in 1909, $33.50 in 1915, and $55.00 in 1921; presumably, World War I affected Coradi's ability to export planimeters. By 1936, a German firm was manufacturing model 4242 for K&E's Paragon product line. Compare to 1998.0032.03. See 1991.0882.02 for a later instruction manual.
- References: Clark McCoy, "Collection of Pages from K&E Catalogs for the 4242 Family of Polar Planimeters," http://www.mccoys-kecatalogs.com/PlanimeterModels/ke4242family.htm; Catalogue of Keuffel & Esser, 33rd ed. (New York, 1909), 322; Catalogue of Keuffel & Esser, 35th ed. (New York, 1915), 315; Catalogue of Keuffel & Esser, 36th ed. (New York, 1921), 257; Catalogue of Keuffel & Esser, 38th ed. (New York, 1936), 340.
- Location
- Currently not on view
- date made
- 1917
- maker
- Coradi, Gottlieb
- ID Number
- 1999.0250.01
- accession number
- 1999.0250
- catalog number
- 1999.0250.01
- maker number
- 25748
- Data Source
- National Museum of American History, Kenneth E. Behring Center
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