Suspension Pantograph in Case by G. Coradi of Zurich Sold by Eugene Dietzgen Company with Stand


This suspended pantograph consists of four hollow steel bars, which form a rectangle with two extended parallel sides. The bars are about twenty-eight inches long. One vertex of the rectangle contains a peg with a rounded tip, which attaches to a heavy iron standard which anchors the pantograph. This standard, painted black, has three paper protective pads underneath it. Two wires stored in the lid of the case connect to the standard at perpendicular corners. These wires hold the arms of the pantograph off the paper, reducing friction in the tracing.

Three of the bars are marked from zero to sixty centimeters by tenths and in ratios from 1:20 to 4:5. Joints with adjustable feet are at the corners. The tracer and pencil points are placed at the far end of one bar and on the crossbar. These points are interchangeable so they can be used in both enlarging and reducing.

When the three arms with divisions are set to the desired ratio, the standard, pencil point, and tracer point lie in the same line. Thus, the pantograph works on the principle of similar right triangles. The tracer is moved over the drawing with an oblong wooden handle. A clip next to the far point holds a string (wrapped around a card in the case) which runs through the corner joint, the other point, and ends at the other corner joint.

The pantograph is stored in a wooden case with a metal handle. Braces inside the case are lined with felt. The case also contains a cleaning rag, two metal disk weights for the pencil, a pencil holder, and two tracer points. The pantograph must be set to the 1:2 ratio to be placed into the case.

A mark inside the lid of the case reads: PANTAGRAPH (/) 8-6-42 (/) From Eng. & Val. Div. Another mark there, inside a box, reads: Prepared in (/) SERVICE DIVISION (/) Income Tax Unit. A printed label filled in with crayon on the bottom of the case reads: TO: NATIONAL PRESS BUILDING (/) Floor 7-[?] (/) Room No. 757 (/) Section Eng (/) Unit No. Draftingroom (/) Employee M E Spear (/) Consolidated Returns, (/) Audit Division. A mark on a metal tag on one bar reads: Eugene Dietzgen Co. A mark engraved on another bar, near the handle for directing the pencil point reads: G. Coradi, Zurich (/) Switzerland (/) No 3777.

Eugene Dietzgen Company of Chicago offered suspended pantographs in its catalogs from at least 1902. This appears to be Dietzgen’s Model No. 1889 which was listed in the Dietzgen Catalogue from 1910 until at least 1949.

The tag on the bottom of the case for the object indicates that it was moved to an office of the Internal Revenue Service at the National Press Building. According to Cosgrove, the IRS moved into that building in 1928 and left in 1930. Hence the object was made by 1928.

The pantograph was sent to M.E. Spear. The 1920 U.S. Census indicates that Mary E. Hunt, then twenty-two years old, was a draftsman living in Washington, D.C., and working for the Internal Revenue Service. By 1924, Hunt had married A. Spear and was living Takoma Park, Md., and still working for the Internal Revenue Service. The 1930 U.S. Census lists a Mary E. Spear, thirty-three years old and living in Takoma Park, Maryland, with her husband Albert A. Spear. From information there, her birthdate appears to be about 1897. By 1935, she is listed in the city directory as a draftsman at the U.S. Department of Labor. In the 1940 U.S. Census, her occupation is given as “analyst.” By 1952, Mary Eleanor Spear, a Visual Information Specialist at the Bureau of Labor Statistics of the U.S. Department of Labor, published Charting Statistics (McGraw-Hill, 1952). She would go on to write Practical Charting Techniques (McGraw-Hill, 1969). The Social Security Death Index lists Mary Spear (1897-1986) who was living in Gaithersburg, Md., at the time of her death.


John Cosgrove, ed. Reliable Sources: The National Press Club in the American Century, Paducah, Ky.: Turner Publishing Company, 1997, p. 141.

Eugene Dietzgen Company, Catalogue, Chicago, 1902 (pp. 149-152), 1904 (pp. 180-182), 1910 (pp. 230-232), 1919 (pp. 93-95), 1921 (pp. 212-214), 1926 (pp. 192-194), 1928 (pp. 197-199), 1938 (pp.252-253), 1949 (pp. 252-253). In these catalogues, the model 1889 is listed from 1910-1949.

Eugene Dietzgen Company, Price List, 1943 (p. 16).

U.S. Census Records, Washington, D.C. city directories, Social Security Death Index, as listed on the website

Date Made: 1910-19301910-1928ca 1942

Maker: Coradi, Gottlieb

Location: Currently not on view

Place Made: Switzerland: Zürich, Zurich

Subject: Mathematics


See more items in: Medicine and Science: Mathematics, Pantographs, Science & Mathematics


Exhibition Location:

Credit Line: Transfer from the Internal Revenue Service

Data Source: National Museum of American History

Id Number: MA.333875Accession Number: 304213Catalog Number: 333875

Object Name: Pantograph

Physical Description: metal (overall material)steel (overall material)wood (overall material)Measurements: overall (instrument in case): 15.5 cm x 139 cm x 14.5 cm; 6 3/32 in x 54 23/32 in x 5 23/32 inseparate stand: 39 cm x 25.5 cm x 25 cm; 15 11/32 in x 10 1/32 in x 9 27/32 in


Record Id: nmah_904630

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