Measuring & Mapping

• Alvergniat Aneroid Barometer

  Description

  This is a brass instrument, 5½ inches diameter and 2¼ inches deep. The printed paper face reads “BAROMÈTRE DE PRÉCISON / POUR STATIONS MÉTÉOROLOGIQUES” and “ALVERGNIAT FRES 10. R. de la Sorbonne” and “BREVETÉ S.G.D.G.” The latter indicates that this instrument, or some part thereof, was covered by a French patent. The pressure scale reads from 700 to 790 cm of mercury, by centimeters. There are also words for weather conditions, in French.

  This came to the Smithsonian in 1910, a transfer from the U.S. Department of the Interior. It had probably been collected by the short-lived federal Bureau of Education.

  Alvergniat Frères were in business in Paris from 1858 until after 1900, manufacturing a wide range of instruments for the various sciences.

  Location

  Currently not on view

  date made

  late 19th century

  maker

  /Alvergniat Freres

  ID Number

  PH.261256

  accession number

  51116

  catalog number

  261256

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• AGA EDM (Geodimeter Model 4B)

  Description

  The Geodimeter Model 4, introduced in the spring of 1959, measured 12 inches square, weighed about 35 lbs (plus the 12-volt battery and inverter), cost less than $5,000, and had a range of 50 feet to 3 miles. Because of its small size and low cost, it was attractive to independent surveyors, especially when advertisements promised that the initial outlay was "easily returned by the savings gained in just a few projects use." Model 4B was similar to the Model 4, but had a slightly different housing. Model 4D used a high-pressure mercury vapor lamp. Advertisements in 1963 boasted: "Now up to 3 miles in brightest sunshine" and "only one instrument, only one operator."

  In 1965, having found that the Model 4 offered the same accuracy as the Model 2, the U. S. Coast and Geodetic Survey, began phasing out the heavier instrument. The Survey also realized that by equipping a Model 4D with a laser they could increase its range and productivity. George "Bud" Lesley, who had used the Model 2 at Cape Canaveral and several Model 4Ds on the transcontinental traverse, had read up on lasers, and was given the task of designing this modification. Within a year Lesley had replaced the mercury vapor lamp with a 2-mw Perkins-Elmer helium neon laser, replaced the Kerr cell with a KDP cell (an electronic shutter), and replaced the original 1P21 phototube with a 56TVP phototube.

  The Coast and Geodetic Survey then put out a call for someone to put lasers in a number of 4Ds. As the low bidder, AGA got Lesley and his prototype for 60 days, and was soon producing the Model 4L. This instrument required an ac generator, but had a range of 42 km at night, and about 21 km in daylight. On one test in Nebraska, the laser Geodimeter measured a 30-km line, "nearly twice the length of previous measurements, with accuracy exceeding one part in a million."

  A July 14, 1968, press release stated that "A major breakthrough in surveying has been achieved with lasers," and quoted Lesley to the effect that "lasers have enabled survey teams to expand by 20 to 50 percent the amount of terrain covered and to increase their accuracy." For this work Lesley received the Colbert Medal of the Society of American Military Engineers.

  This example is a Model 4B that belonged to the Coast and Geodetic Survey. It is marked "AGA STOCKHOLM SWEDEN X590315 nr 284 NASM-4B." It was made in the period 1960-1964, and was still in use in 1976. The original lamp was replaced with a 2 milliwatt laser in 1969, and a 6 milliwatt laser in 1971.

  Ref: AGA, Geodimeter System Bergstrand Model 4D (March 15, 1964).

  George B. Lesley, "Laser Geodimeter," Surveying and Mapping 27 (1967): 625-631.

  Location

  Currently not on view

  maker

  AGA

  ID Number

  1986.0395.03

  accession number

  1986.0395

  catalog number

  1986.0395.03

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• David White Theodolite

  Description

  This 9-inch theodolite was made for the U. S. Coast and Geodetic Survey, and designed for first order triangulation. It dates from the mid-1930s. New, it cost $2,175. It is marked "David White Co. Milwaukee Wis. No. 9049" and "USC&GS No. G362." The horizontal circle is graduated to degrees, and read by opposite micrometers with drum dials to 30 seconds. The vertical circle is graduated to 10 minutes, and read by opposite verniers and magnifiers to single minutes. The David White Co. was established in 1895, and renamed the David White Instrument Co. in 1956.

  Ref: David White Co., Catalog A, 7th edition (Milwaukee, Wisconsin, about 1937), pp. 103-104.

  maker

  David White Co.

  ID Number

  1986.0395.11

  accession number

  1986.0395

  catalog number

  1986.0395.11

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  "American Method in Astronomical Observation"

  Description

  From its infancy, timekeeping has depended on astronomy. The motion of celestial bodies relative to the rotating Earth provided the most precise measure of time until the mid-twentieth century, when quartz and atomic clocks proved more constant. Until that time, mechanical observatory clocks were set and continuously corrected to agree with astronomical observations.

  The application of electricity to observatory timepieces in the late 1840s revolutionized the way American astronomers noted the exact movement of celestial events. U.S. Coast Survey teams devised a method to telegraph clock beats, both within an observatory and over long distances, and to record both the beats and the moment of observation simultaneously. British astronomers dubbed it the "American method of astronomical observation" and promptly adopted it themselves.

  Transmitting clock beats by telegraph not only provided astronomers with a means of recording the exact moment of astronomical observations but also gave surveyors a means of determining longitude. Because the Earth rotates on its axis every twenty-four hours, longitude and time are equivalent (fifteen degrees of longitude equals one hour).

  In 1849 William Cranch Bond, then director of the Harvard College Observatory, devised an important improvement for clocks employed in the "American method." He constructed several versions of break-circuit devices—electrical contracts and insulators attached to the mechanical clock movement—for telegraphing clock beats once a second. The Bond regulator shown here incorporates such a device. Bond's son Richard designed the accompanying drum chronograph, an instrument that touched a pen to a paper-wrapped cylinder to record both the beats of the clock and the instant of a celestial event, signaled when an observer pressed a telegraph key.

  Location

  Currently not on view

  Date made

  ca 1850

  maker

  William Bond & Son

  ID Number

  1981.0322.01

  accession number

  1981.0322

  catalog number

  1981.0322.01

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Indenture of William J. Young

  Description

  With this indenture, signed on January 30, 1813, William J. Young (1800-1870) became an apprentice to Thomas Whitney. The indenture details the conditions under which Young would work over the course of the next seven years, as well as Whitney's agreement to teach him "the Trade or Mystery of a Mathematical Instrument Maker." Alfred C. Young donated his great-grandfather's indenture to the Smithsonian in 1981.

  In 1820, having earned his freedom and with $30 in his pocket, Young went into business on his own. His was soon the leading mathematical instrument shop in the United States. Here he introduced improved forms of the railroad compass, the solar compass, and the surveyor’s transit. And here he trained younger men to carry on the tradition.

  Young was the first American to own a dividing engine—a device for mechanically dividing circles into degrees and minutes. He would not have needed such a complex and costly device just to make compasses, but he would need it to graduate the circles of more precise instruments. Not having the money to purchase a dividing engine from England, Young built his own. He had never seen a dividing engine, but worked from a printed description of an English engine. He would later modify this original engine, and build two others.

  Young signed his earliest instruments "W. J. Young Maker Philadelphia [or Philada]." He changed his signature to "Wm. J. Young Maker Philadelphia [or Philada]" around 1840, and began marking serial numbers on his instruments around 1853. These numbers began around 3000, and probably indicate the number of Young instruments to date. Analysis of these serial numbers shows that Young produced some 65 instruments per year in the 1850s, with annual production rising to 120 in the early 1900s.

  While 18th-century American instrument makers tended to work alone, or with an apprentice or two, Young usually had ten or so men in his shop, some apprentices and some journeymen. These men were all highly skilled and commanded relatively high wages. The instruments they produced were substantially more costly than those produced in factories, such as that of W. & L. E. Gurley.

  William J. Young joined with Charles S. Heller and Thomas N. Watson in 1866, and began trading as William J. Young & Co. The partnership disbanded in 1870, Alfred Young, a son of William, operated the firm as Wm. J. Young & Sons, and Heller went on to form Heller & Brightly. Alfred Young's firm began signing its instruments Young & Sons in 1875, and began using this name in advertisements around 1882. Young & Sons was incorporated in 1917. Keuffel & Esser obtained control of the firm in 1918, made it the Y&S department of K&E, and moved the operations to the K&E factory in Hoboken, N. J.

  Ref: Deborah Jean Warner, "William J. Young. From Craft to Industry in a Skilled Trade," Pennsylvania History 52 (1985): 53–68.

  Robert C. Miller, "Dating Young Instruments," Rittenhouse 5 (1990): 21-24.

  Location

  Currently not on view

  ID Number

  1981.0511.02

  accession number

  1981.0511

  catalog number

  1981.0511.02

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Lady's Pocket Watch

  Description

  This tiny watch, with a movement made by the American Watch Company, Waltham, Mass., was the gift of Philip Cadmus to his fiancée Augusta Francis Stipp in 1906, shortly before their marriage.

  Cadmus, a watchmaker, had his photo applied to the dial. The gold case, engraved with the monogram “A.F.S.”, is the hunter style, with a cover over the dial of the watch and the winding stem positioned at three on the dial. The movement is serial number 11647977. Preserved with the watch are its protective cloth sack and velvet-covered presentation box.

  Location

  Currently not on view

  date made

  1906

  maker

  Waltham Watch Company

  ID Number

  1981.0691.01

  catalog number

  1981.0691.01

  accession number

  1981.0691

  maker number

  735

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Datalizer Universal English/SI Converter Slide Rule

  Description

  This white rectangular cardboard rule is held together with four metal rivets. The front has logarithmic scales for making measurement conversions for length, mass, area, and volume. A chart for converting temperatures runs along the bottom edge. The top is marked: THE NEWS (/) NEW YORK'S PICTURE NEWSPAPER Universal ENGLISH/SI (metric) Datalizer. The bottom is marked: © 1976 datalizer by DATALIZER SLIDE CHARTS, INC., Addison, IL 60101 PRINTED IN U.S.A. FORM NO. EM2.

  The back has charts for converting between cubic meters and cubic feet; gallons and liters; miles and kilometers; inches and centimeters; and fractional inches and millimeters. A table of miscellaneous conversions appears in the center of the back.

  Around 1960 a former employee of the Perry Graf Corporation (see 1979.3074.03) established Datalizer in Addison, a Chicago suburb. The company made this promotional rule during a time of considerable interest in adopting the metric system in the United States. The New York Daily News used the "picture newspaper" slogan between 1920 and 1991.

  References: "Slide Chart Specialists," Datalizer Slide Charts, http://www.datalizer.com/about-us/; Lance Gould, "The Lenses And Legacy Of New York's Picture Newspaper," New York Daily News, January 25, 2002, http://articles.nydailynews.com/2002-01-25/entertainment/18195567_1_photographers-gallery-exhibit-exposed.

  Location

  Currently not on view

  Currently not on view

  date made

  1976

  maker

  Datalizer Slide Charts, Incorporated

  ID Number

  1981.0922.15

  catalog number

  1981.0922.15

  accession number

  1981.0922

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Conversion Factors, Reference Table for Engineers and Other Executives

  Description

  This battered table, printed on heavy green paper, gives an alphabetical list of units of measure, conversion factors, and new units of measure. For example, for the unit of measure centimeters, the conversion factor is 0.3937. Multiplying a measurement in centimeters by the conversion factor gives a result in inches.

  The table was distributed by Precision Equipment Company of Chicago, Illinois. The back of the table advertises the company’s shelving and safety steps. A sentence at the bottom of the chart reads: Reproduced with the Permission of Foxboro Co. and Exporters’ Digest.

  The owner of the table inserted a row with the conversion factor of 1.151 for converting from nautical miles to statute miles.

  Exporters’ Digest was published from 1927 through 1958. Foxboro Company was in business from 1912 through 1990. A surviving piece of trade literature suggests that the Precision Equipment Company was in business in the 1950s. Hence the rough date of 1950 assigned to the object.

  Location

  Currently not on view

  date made

  ca 1950

  ID Number

  1981.0922.16

  accession number

  1981.0922

  catalog number

  1981.0922.16

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Lowe's Graphic Hygrometer

  Description

  Nathaniel M. Lowe, the manufacturer of Edson's Hygrodeik, designed a similar but somewhat simpler instrument for showing the dew point and relative humidity. In this example, the chart is on a white enamel plate marked "LOWE'S Graphic hygrometer" and a monogram. It came to the Smithsonian from Trenton State University.

  Ref: N. M. Lowe, "Psychrometers," U.S. Patent 202276 (1878).

  Location

  Currently not on view

  maker

  Lowe, Nathaniel M.

  ID Number

  1982.0230.11

  accession number

  1982.0230

  catalog number

  1982.0230.11

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Faber-Castell Map Measure Sold by U. S. Blue Co.

  Description

  This metal map measure consists of a slender tubular handle attached to a dial with a wheel protruding from the bottom. The white paper dial is covered by glass and has a thin blue metal arrow attached in the center. The arrow moves as the wheel is traced along a map. The outer ring of the dial is marked by threes from 0 to 39 for converting inches to miles or inches to verstes (a traditional Russian length measure equivalent to 3,500 feet). The inner ring is divided by units and numbered by tens from 0 to 100 for converting centimeters to kilometers.

  The center of the dial is marked: Made in (/) Switzerland (/) U.S. BLUE CO. (/) CHICAGO. The metal between the dial and the wheel is marked: F C (/) DEPOSE. The Faber-Castell logo of a castle is between the letters F and C. The letter B is scratched into the back of the instrument.

  The German company A. W. Faber was renamed Faber-Castell in 1905. It sometimes manufactured products in Switzerland, and "depose" suggests that the firm filed for a trademark there. U.S. Blue was presumably a blueprint company located in Chicago; it also sold slide rules from Hemmi. The Eugene Dietzgen Co. also sold this instrument, charging $2.20 in 1926. Alfred J. Betcher (1887–1971) owned this example, perhaps purchasing it when he was studying at the University of Minnesota (1906) or at West Point (1907–1911). He was commissioned as a captain, served at posts in New York, Vermont, and Kentucky, and retired in 1939 at the rank of lieutenant-colonel. In 1940 he was elected mayor of Canajoharie, N.Y.

  References: Russ Rowlett, How Many? A Dictionary of Units of Measurement, July 11, 2005, http://www.unc.edu/~rowlett/units/index.html; Catalogue & Price List of Eugene Dietzgen Co., 12th ed. (Chicago, 1926), 171; accession file.

  Location

  Currently not on view

  date made

  ca 1910

  maker

  Faber, A. W.

  ID Number

  1982.0386.07

  accession number

  1982.0386

  catalog number

  1982.0386.07

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Railroad Watch

  Description

  Railroad managers learned that to have their lines run on time, they needed to issue accurate timepieces to their employees. This watch was made in 1869 by Elgin National Watch Company, Elgin, Ill., under contract to the Pennsylvania Railroad. Outside case back is engraved "449," the number of the locomotive on which the watch was used. The "449" was a Baldwin 10-wheeler delivered to the railroad in July 1869.

  The watch is an 18-size, 15-jewel key-wind movement in silver case. Movement marked: "B.W. Raymond / Patent Pinion / No. 69170 / Elgin, Ills." The B. W. Raymond model was named for Elgin’s first president, who also had been mayor of Chicago twice and president of the Elgin and State Line Railroad Co. Inside of dust cap marked: "7431." Inside of case back stamped: "J. R. Reed & Co. / Pitts / Coin / 7431." Dial reads: "PENNSYLVANIA RAILROAD CO." Its steel winding key survives.

  Location

  Currently not on view

  date made

  ca 1869

  manufacturer

  Elgin National Watch Co.

  ID Number

  1982.0517.01

  accession number

  1982.0517

  catalog number

  1982.0517.01

  serial number

  69170

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Pocket Watch

  Description

  The Peoria Watch Co., Peoria, Ill., made this high-grade watch. The movement is marked with the company’s name and serial number 17672. The dial indicates the watch could be used for railroad timekeeping, where the most reliable watches and clocks were fundamental to safe and efficient operation. The definition of a railroad watch changed over time and varied among railroad companies in the nineteenth century, but by about 1920 generally accepted, closely specified standards governed almost every detail of watch construction for railway use.

  Location

  Currently not on view

  date made

  ca 1887

  manufacturer

  Peoria Watch Co.

  ID Number

  1982.0518.001

  catalog number

  1982.0518.001

  accession number

  1982.0518

  serial number

  17672

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Rubidium Frequency Standard, Model FRK

  Description

  This object, marked “F. Nr. E250/116,” is an unflown back-up for two rubidium frequency standards installed on NTS-1, the first of the Navigation Technology Satellites (NTS) launched to validate the key concepts and hardware for the Global Positioning System (GPS). NTS-1 (originally named Timation III) was built at the Naval Research Laboratory (NRL), Washington, D.C. It was launched in July 1974 and carried the first atomic clocks into space.

  The compact rubidium frequency standard for NTS-1 is the Model FRK made by Efratom Elektronik, Munich, Germany. Gerhard Hübner and Ernst Jechart established the firm in 1971 and a year later supplied examples of the clock to NRL. Researchers had constructed relatively large laboratory rubidium frequency standards in the 1950s, and portable commercial versions were available by the mid1960s. But the FRK—weighing roughly three pounds and measuring about four inches on a side—was the smallest frequency standard of any type available in the early 1970s and attractive for space applications. NRL modified the commercial model for use in space, specifically to permit controlling its rate and frequency output from the ground.

  Efratom established a branch in Irvine, California, in 1973 and manufactured compact rubidium frequency standards there for a variety of customers. The firm became a division of Ball Aerospace in 1982 and then part of Datum in 1995. Symmetricom acquired Datum in 2002.

  Reference:

  1. Carroll O. Alley et al., “Performance of the New Efratom Optically Pumped Rubidium Frequency Standards and Their Possible Application in Space Relativity Experiments,” Proc. of the 4th Ann. Precise Time and Time Interval (PTTI) Appl. and Planning Meeting, 1972, 29-40.

  2. Stephen A. Nichols, Joseph D. White and Danzy, Frederick. Design and Ground Test of the NTS-1 Frequency Standard System. Naval Research Laboratory Report 7904. Washington, D.C., September 5, 1975.

  Brief description of an atomic clock

  Electromagnetic waves of very specific and consistent frequencies can induce atoms to fluctuate between two energy states, and by measuring that frequency we can determine the “tick” of an atomic clock. A second in a cesium clock, for example, is defined as 9,192,631,770.0 cycles of the frequency that causes the cesium atom to jump between those states. Different atoms “tick” at different rates – strontium atoms tick about 10,000 times faster than cesium atoms – but all atoms of a given element tick at the same rate, making atomic clocks much more consistent than clocks based on macroscopic objects such as pendulums or quartz crystals.

  Steven Jefferts, physicist, National Institute of Standards and Technology.

  For additional background information go to:

  http://www.nist.gov/pml/div688/timekeeping.cfm

  maker

  Efratom

  ID Number

  1982.0634.01

  catalog number

  1982.0634.01

  accession number

  1982.0634

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  F.T.S. Cesium-Beam Frequency Standard

  Description

  This was the first in a series of cesium pre-production frequency standards developed in the 1970s by Frequency & Time Systems Inc. (FTS), Danvers, Mass. Two cesium clocks based on this early instrument, or “brassboard,” were aboard NTS-2, the second of the Navigation Technology Satellites (NTS) launched to validate the key concepts and hardware for the Global Positioning System (GPS). Built at the Naval Research Laboratory, Washington, D.C., NTS-2 was launched in June 1977.

  FTS was founded in Danvers, Mass., in 1971 and later became a subsidiary of Datum Inc. Symmetricom acquired Datum in 2002.

  Reference:

  Martin W. Levine, “Performance of a Preproduction Model Cesium Beam Frequency Standards for Spacecraft Applications,” Proc. of the 10th Ann. Precise Time and Time Interval (PTTI) Appl. and Planning Meeting, 1978, 169-193.

  Brief description of an atomic clock

  Electromagnetic waves of very specific and consistent frequencies can induce atoms to fluctuate between two energy states, and by measuring that frequency we can determine the “tick” of an atomic clock. A second in a cesium clock, for example, is defined as 9,192,631,770.0 cycles of the frequency that causes the cesium atom to jump between those states. Different atoms “tick” at different rates – strontium atoms tick about 10,000 times faster than cesium atoms – but all atoms of a given element tick at the same rate, making atomic clocks much more consistent than clocks based on macroscopic objects such as pendulums or quartz crystals.

  Steven Jefferts, physicist, National Institute of Standards and Technology.

  For additional background information go to:

  http://www.nist.gov/pml/div688/timekeeping.cfm

  maker

  Frequency & Time Systems Inc.

  ID Number

  1982.0634.03

  catalog number

  1982.0634.03

  accession number

  1982.0634

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Declinometer

  Description

  A declinometer measures the horizontal angle between the geographic and magnetic poles of the earth (also known as the declination, or variation, of the magnetic needle). This particular form was introduced by H. P. Gambey of Paris in the 1830s and remained popular in France throughout the century. This example was purchased in France and was probably produced there as well. It consists of a heavy stone base, a bar magnet supported by a thread, and microscopes at either end to read the magnet's position.

  Ref: E. Mascart, Traite; de Magnetism Terrestre (Paris, 1900), p. 189-190.

  Location

  Currently not on view

  Date made

  ca 1830-1845

  maker

  Gambey, Henri Prudence

  ID Number

  1982.0668.01

  accession number

  1982.0668

  catalog number

  1982.0668.01

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Universal Magnetometer with Dip Circle

  Description

  This instrument is marked "D.T.M. C.I.W. N° 19." Designed and built by the Department of Terrestrial Magnetism of the Carnegie Institution of Washington in 1912, it incorporates an astronomical telescope and magnetometer for the determination of magnetic declination and horizontal intensity, and a dip circle with a Lloyd-Creak attachment for the determination of inclination and intensity. It is relatively light and easy to manipulate. It was used for a few years and then set aside when the universal magnetometer with earth inductor came into use.

  This magnetometer was probably transferred to the U.S. Coast and Geodetic Survey after the Carnegie Institution closed its geomagnetic program. The U.S. Geological Survey acquired it in 1973, when it took over the geomagnetic program of the federal government, and transferred it to the Smithsonian in 1982.

  Ref: J. A. Fleming, "Two New Types of Magnetometers Made by the Department of Terrestrial Magnetism of the Carnegie Institution of Washington," Terrestrial Magnetism 16 (1911): 1-12.

  Carnegie Institution of Washington, Land Magnetic Observations, 1911-1913 (Washington, D.C., 1915), pp. 7-8.

  Location

  Currently not on view

  Date made

  1912

  maker

  Carnegie Institution of Washington. Department of Terrestrial Magnetism

  ID Number

  1982.0671.03

  accession number

  1982.0671

  catalog number

  1982.0671.03

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Universal Magnetometer with Earth Inductor

  Description

  This instrument was designed and produced by the Department of Terrestrial Magnetism of the Carnegie Institution of Washington. Unlike the Carnegie's original universal magnetometer, this one is equipped with an earth inductor to determine dip. It is marked "DEPARTMENT TERRESTRIAL MAGNETISM Carnegie Institution of Washington E.I. - M. No. 28." It was completed in 1914 and used in many locations around the world. The U.S. Coast and Geodetic Survey used it in South and Central America in the early 1940s. The U.S. Geological Survey acquired it in 1973, when that agency took charge of the federal program in geomagnetism, and transferred it to the Smithsonian in 1982.

  Ref: J. A. Fleming and J. A. Widner, "Description of the C.I.W. Combined Magnetometer and Earth Inductor," Terrestrial Magnetism 18 (1913): 105-110.

  Carnegie Institution of Washington. Department of Terrestrial Magnetism. Land Magnetic Observations, 1911-1913 (Washington, D.C., 1915), pp. 9-12.

  U. S. Coast and Geodetic Survey, Magnetic Observations in the American Republics 1941-44 (Washington, D.C., 1946), p. 16.

  Location

  Currently not on view

  Date made

  1914

  maker

  Carnegie Institution of Washington. Department of Terrestrial Magnetism

  ID Number

  1982.0671.07

  accession number

  1982.0671

  catalog number

  1982.0671.07

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• Gurley Surveyor's Compass

  Description

  This resembles Gurley’s small vernier compass but has no vernier mechanism. The outer rim of the box is graduated to single degrees, and numbered every 10 degrees. The instrument can be used with the folding sights raised to the vertical, or with the sighting bar. In the latter case, the folding sights are folded towards each other, to form a tent, and the sighting bar attached on top. The sighting bar is equipped with a vertical circle graduated to single degrees. This form has not been found listed or described in any Gurley trade literature. The "W. & L. E. Gurley, Troy, N.Y." inscription was engraved by machine, dating it to after 1876.

  Location

  Currently not on view

  maker

  W. & L. E. Gurley

  ID Number

  1982.0701.06

  accession number

  1982.0701

  catalog number

  1982.0701.06

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• Gurley Transit

  Description

  Gurley described this as a Surveyor's Transit with two verniers to the horizontal limb. The horizontal and vertical circles are silvered, graduated every 30 minutes of arc, and read by verniers to single minutes. There is a clamp and tangent to the telescope axis. A variation scale on the face of the compass extends 30 degrees either way; the double folded vernier reads to single minutes. The transit is easily detached from the leveling head, and the two are stored separately in the box. Since the "W. & L. E. Gurley, Troy, N.Y." signature was engraved by hand, this transit was made between 1852, when Gurley began in business, and 1876, when Gurley's new engraving machine was up and running.

  Ref: W. & L. E. Gurley, Manual of the Principal Instruments used in American Engineering and Surveying (Troy, N.Y., 1871).

  Location

  Currently not on view

  maker

  W. & L. E. Gurley

  ID Number

  1982.0701.07

  accession number

  1982.0701

  catalog number

  1982.0701.07

  Data Source

  National Museum of American History, Kenneth E. Behring Center

• 

  Variometer

  Description

  This instrument belonged to the Carnegie Institution of Washington, and was probably made in the early 1900s by Max Thomas Edelmann of Munich.

  Ref: M. Th. Edelmann, "On the Construction of Earth-Magnetic Instruments," Weather Bureau Bulletin 11 (1893): 511-539.

  Location

  Currently not on view

  maker

  Edelmann, Max Thomas

  ID Number

  1983.0039.05

  accession number

  1983.0039

  catalog number

  1983.0039.05

  Data Source

  National Museum of American History, Kenneth E. Behring Center

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