Set Squares

Many of the set squares in the mathematics collection are early modern treasures handcrafted in Europe. A particularly interesting example has a then-new metric scale. (See also the scale rules group for information on the history of length measures.) Also included on this page are sets of drawing instruments that contain set squares and artillery squares, used to design fortifications and position artillery.

This 6-1/2" brass rule unfolds to form a set square. The outer edge of one leg has a scale for German inches (roughly 1-1/32 English inches), numbered by ones from 1 to 6. The first unit is divided into twelfths. The scale is marked: Demy pied de Rhin [half a foot of the Rhine].
Description
This 6-1/2" brass rule unfolds to form a set square. The outer edge of one leg has a scale for German inches (roughly 1-1/32 English inches), numbered by ones from 1 to 6. The first unit is divided into twelfths. The scale is marked: Demy pied de Rhin [half a foot of the Rhine]. The inner edge of this leg has a scale numbered by tens from -10 to 50. The first unit is divided into tenths. The scale is marked: Eschelle [scale]. This leg is also marked: CHAPOTOT A PARIS.
Both edges of the other leg have scales for French inches (roughly 1-1/16 English inches), numbered by ones from 1 to 6. The first unit on the outer edge is divided into twelfths. The leg is marked: Demy pied de Roy [half a foot of the French king]. This leg has a pinhole and a larger hole (1/4" diameter) for hanging plumb lines. Compare to 1985.0580.03, 316929, 317362, and 316914.
Louis Chapotot and his son, Jean, were prolific instrument makers with a workshop at Quay de l'Horloge du Palais à la Sphère Royale in Paris. Louis is known to have been active around 1670 to 1700, and Jean worked from about 1690 to 1721.
Albert Haertlein (1895–1960), who collected this square, graduated with a bachelor's degree in civil engineering from the Massachusetts Institute of Technology in 1918. He served in the engineering corps of the U.S. Army during World War I and taught engineering at Harvard from 1919 until 1959. Haertlein was prominent in the American Society of Civil Engineers.
References: J. A. Bennett, "New Acquisition: 'La planchette,'" Sphaera no. 9 (Spring 1999), https://www.mhs.ox.ac.uk/sphaera/issue9/articl4.htm; Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/; "News From the Classes," Technology Review 21 (1919): 645; Albert Haertlein, Papers, HUG4444, Harvard University Archives, Cambridge, Mass.
Location
Currently not on view
date made
1670-1721
maker
Chapotot, Louis
Chapotot, Jean
ID Number
1985.0580.02
accession number
1985.0580
catalog number
333927
A square is an instrument used to draw lines perpendicular to other lines. It also can be used to test whether two lines are perpendicular. Squares in which the arms are fixed date from ancient times.
Description
A square is an instrument used to draw lines perpendicular to other lines. It also can be used to test whether two lines are perpendicular. Squares in which the arms are fixed date from ancient times. By the 16th century, they also were made from two rules hinged together at one end so that they fold up compactly, allowing them to fit conveniently into a case of drawing instruments. See MA.316914, MA.335353, 1979.0876.01, and 1984.1070.01.
Early modern squares often had plumb bobs for finding a vertical axis, as in a building under construction. While most others in the collection were lost before they arrived at the Smithsonian, this fixed-leg, L-shaped brass instrument retains its plumb bob, which is tied to a string that runs through a pinhole at the square's vertex. On one side, the long leg of this instrument has a scale divided into units of about 7/16". The scale is numbered by tens from 10 to 100 and is marked: Echelle De 100 parties [scale of 100 parts]. The first unit is divided into tenths and numbered from 1 to 10. This side is also marked: N Bion AParis.
On the other side, the long leg has a scale divided into units of about 7/8". The scale is numbered by tens from 60 to 10 and is marked: Echelle de 60 parties [scale of 60 parts]. The first unit is divided into tenths and numbered from 10 to 1. The outer edge has a scale of French inches (about 1-1/16" English inches) numbered by ones from 5 to 1. The largest unit is divided into twelfths and numbered by threes from 12 to 3. This scale is marked: Pouce de Roy [inch of the French king].
The short leg has a scale divided into units of about 1-25/32". The scale is numbered by tens from 10 to 20 and is marked: Echelle de 20 parties [scale of 20 parts]. The first unit is divided into tenths and numbered from 1 to 10. The outer edge has a scale of French inches numbered by ones from 1 to 4. The largest unit is divided into twelfths and numbered by threes from 3 to 12. This scale is marked: pouce de roy [inch of the French king].
Nicolas Bion (about 1652–1733) made and sold mathematical instruments in Paris in his own shop and as royal maker for Louis XIV. He prepared a famous 1709 manual on the construction and use of mathematical instruments. 1980.0580.05 and MA.321675, two sectors in the collections, also came from his workshop. The Smithsonian acquired this object in 1959. Henry Russell Wray, the previous owner, graduated from the University of Pennsylvania and was a businessman in Colorado Springs, Colo., in the early 20th century.
References: Maya Hambly, Drawing Instruments, 1580–1980 (London: Sotheby's Publications, 1988), 105; Nicholas Bion, The Construction and Principal Uses of Mathematical Instruments, trans. Edmund Stone (London: for John Senex, 1723), 12, Plate 2.
Reference:
Sotheby & Company, Catalogue of a Collection of Scientific Instruments, the Property of the Late Henry Russel Wray, London, 1959 (a copy of the catalogue is in the accession file).
Location
Currently not on view
date made
1681-1733
maker
Bion, Nicholas
ID Number
MA.316929
catalog number
316929
accession number
228694
This brass semicircular protractor is divided by single degrees and marked by fives from 5° to 180°. The letter X is at the 90-degree mark. The upper right side of the protractor contains a shadow square.
Description
This brass semicircular protractor is divided by single degrees and marked by fives from 5° to 180°. The letter X is at the 90-degree mark. The upper right side of the protractor contains a shadow square. This is divided on both sides into sets of four units, each approximately 3/8" long and numbered from 1 to 12, for a total of 48 units on each side. The vertical side is marked: OMBRA VERSA. The horizontal side is marked (upside down): OMBRA RETTA.
The scale on the "ombra versa" side measured tangents from 0 to 45°. The scale on the "ombra retta" (or "recta") side measured tangents from 45° to 90°. The lines for degrees and on the shadow square appear to be made by hand, perhaps by placing the instrument next to a pattern. The instrument is decorated with floral and solar motifs. The protractor rests in a brass base that unfolds to form a limb, which is chipped. There are two holes in the limb; the numbers 2 and 1 are scratched next to the holes. There are four holes in the base; the numbers 3 and 1 are scratched next to the outermost holes, which align with the holes on the limb. This instrument is Italian in origin and was likely made before 1800. New York University donated the object in 1963.
Reference: J. A. Bennett, The Divided Circle (Oxford, 1987), 42–43.
Location
Currently not on view
date made
18th century
ID Number
MA.326978
catalog number
326978
accession number
1990.0646
This 6-7/8" brass rule unfolds to form a set square. The outer edge of one leg has a scale for French inches (roughly 1-1/16 English inches), numbered by ones from 1 to 6. The first unit is divided into twelfths and numbered by threes from 3 to 12.
Description
This 6-7/8" brass rule unfolds to form a set square. The outer edge of one leg has a scale for French inches (roughly 1-1/16 English inches), numbered by ones from 1 to 6. The first unit is divided into twelfths and numbered by threes from 3 to 12. The scale is marked: demy pied de Roy [half a foot of the French king]. The inner edge of this leg has a scale for English inches numbered by ones from 1 to 6. The first unit is divided into twelfths and numbered by threes from 3 to 12. The scale is marked: demy pied des Londres [half a London foot].
This leg is also marked: Pre le Maire (/) AParis. It has a pinhole for hanging a plumb bob and a rectangular hole with a rounded end (approximately 1" long) for viewing the plumb bob. The other leg has a diagonal scale, numbered vertically by ones from 1 to 10 and horizontally by twenties from 100 to 20, and a plotting scale that is numbered by hundreds from 100 to 900. Each unit is about 9/16" long. The plotting scale has eleven horizontal lines; the sixth line is marked "5" at each unit of the scale.
Pierre Le Maire (1717–1785) took over his father Jacques's workshop in the late 1730s. Large numbers of his sundials, mathematical instruments, and lodestones survive. Albert Haertlein (1895–1960), who collected this square, graduated with a bachelor's degree in civil engineering from the Massachusetts Institute of Technology in 1918. He served in the engineering corps of the U.S. Army during World War I and taught engineering at Harvard from 1919 until 1959. Haertlein was prominent in the American Society of Civil Engineers.
References: Nicholas Bion, The Construction and Principal Uses of Mathematical Instruments, trans. Edmund Stone (London: for John Senex, 1723), 12, Plate 2; Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures; "News From the Classes," Technology Review 21 (1919): 645; Albert Haertlein, Papers, HUG4444, Harvard University Archives, Cambridge, Mass.
Location
Currently not on view
date made
ca 1735-1785
maker
Le Maire, Pierre
ID Number
1985.0580.03
accession number
1985.0580
catalog number
333928
This 4-1/2" brass rule unfolds to form a set square. The outer edge of one leg has a scale for German inches (roughly 31/32 English inches), numbered by ones from 4 to 1. The first unit is divided into twelfths and numbered by threes from 3 to 12.
Description
This 4-1/2" brass rule unfolds to form a set square. The outer edge of one leg has a scale for German inches (roughly 31/32 English inches), numbered by ones from 4 to 1. The first unit is divided into twelfths and numbered by threes from 3 to 12. The scale is marked: Pouces du Rhin [inches of the Rhine]. The inner edge of this leg has a scale numbered by tens from 10 to 50. The 5 point is also marked. The scale is marked: Eschelle [scale].
The outer edge of the other leg has a scale for French inches (roughly 1-1/16 English inches), numbered by ones from 1 to 4. The first unit is divided into twelfths and numbered by threes from 3 to 12. The scale is marked: pouces de Roy [inches of the French king]. The inner edge of this leg has a scale numbered by tens from 10 to 60. The 5 point is also indicated. This leg has a pinhole for hanging a plumb line and a rectangular hole with a rounded end (approximately 25/32" long) for viewing the plumb bob. This leg is also marked: Desnos AParis. Compare to 1985.0580.02, 1985.0580.03, MA.316929, and MA.316914.
Louis-Charles Desnos was a cartographer and globemaker in France from about 1753 to 1782. Another plumb rule by Desnos is shown at http://teodolite.it/desnos.htm.
Reference: Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/.
Location
Currently not on view
date made
ca 1753-1782
maker
Desnos, Louis-Charles
ID Number
MA.317362
accession number
230278
catalog number
317362
This 18th-century pocket-sized wooden case is covered with black fish skin. It currently holds ten drawing instruments:1) A 4" brass semicircular protractor, divided to single degrees and numbered by tens in both directions from 10 to 180.
Description
This 18th-century pocket-sized wooden case is covered with black fish skin. It currently holds ten drawing instruments:
1) A 4" brass semicircular protractor, divided to single degrees and numbered by tens in both directions from 10 to 180. It is marked: Butterfield AParis.
2) A 6-3/4" brass folding combination set square and ruler. The outer edges of the legs have scales for French inches, numbered by ones from 1 to 6. The inner edges are divided to ten degrees and numbered from 5 to 110. One leg is marked: Demi Pied de Roi [half a king's foot] (/) Butterfield AParis. This leg has a slit and pinhole for hanging a plumb line and a rounded cut-out. The other leg is marked: 6 pouces du vin [6 inches of wine].
3) A 6-3/4" brass French-style sector with straight edges. One side has double scales of equal parts, running from 10 to 200 (misnumbered as 120); of planes (unlabeled), running from 10 to 60; and for inscribed regular polygons, from 12 sides to 3 sides. The outer edge of one leg has an unlabeled scale for the size of artillery shot, running from 4 to 24.
The other side has double scales of chords, running from 10 to 180; of solids, running from 5 to 60; and for the specific weights of five metals. The outer edge of one leg has an unlabeled scale for the weight of artillery shot, running from 4 to 24. This side is marked: Butterfield (/) AParis. Compare to MA.321676, MA.321677, and 1985.0580.04.
4) A 4-1/2" brass dotter, for marking a paper so that the lines of the drawing could be filled in later.
5) A second 6-3/4" brass folding combination set square and ruler. The outer edge of one leg has a scale for French inches, numbered by ones from 1 to 6, and a slot, pinhole, and rectangular cutout for a plumb line. This leg is marked: Langlois aux Galleries du Louvre AParis. The other leg has a plotting scale numbered by hundreds from 100 to 900, with a diagonal scale at the left end.
6) A pair of 4-3/4" brass and steel dividers.
7) A pair of 4" brass and steel dividers with a removable point.
8) A brass dotter attachment that would fit the longer dividers if one point could be removed.
9) A pencil point that nearly fits the smaller dividers.
10) A brass and steel pen point that fits the smaller dividers.
As was typical for sets of drawing instruments, there is not a one-to-one correspondence between the slots in the case and the instruments stored in them. Draftsmen often purchased cases and drawing instruments separately, buying only what they actually used. Over time, instruments were also lost or replaced.
Michael Butterfield (1635–1724) was an English instrument maker who worked in France from around 1677 until his death. He was best known for his distinctive sundials. Claude Langlois (d. 1756) and his successors operated a workshop in Paris from 1730 to 1780. The Smithsonian acquired this object in 1959. Henry Russell Wray, the previous owner, graduated from the University of Pennsylvania and was a businessman in Colorado Springs, Colo., in the early 20th century.
References: Maya Hambly, Drawing Instruments, 1580–1980 (London: Sotheby's Publications, 1988), 24, 28, 134–135; Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/.
Location
Currently not on view
date made
mid 18th century
maker
Butterfield, Michael
ID Number
MA.316914
accession number
228694
catalog number
316914
By the 17th century, makers of scientific instruments collected together a range of tools useful for making drawings in surveying, navigation, architecture, and engineering and sold these collections as sets in cases.
Description
By the 17th century, makers of scientific instruments collected together a range of tools useful for making drawings in surveying, navigation, architecture, and engineering and sold these collections as sets in cases. Sets of drawing instruments allow modern observers to examine a variety of drawing instruments—such as dividers, compasses, pens, rulers, and protractors—at one time. They also provide a sense of what makers and practitioners thought someone starting to work in one of these fields needed in order to be successful.
Marks on the proportional dividers and calipers indicate that the workshop of J. D. Weickert of Leipzig, Germany, manufactured this set. This firm, later known for making felt for piano hammers, was established in 1783 and remains in business as of 2013 (as Filzfabrik Wurzen). The style and condition of the multilayered case suggest the set was made no later than the mid-19th century. The donor received this set of instruments from a distant relative, Gunther Mathies, who emigrated from Germany in the early 20th century and worked for the Thomaston Clock Company in Connecticut.
Two semicircular brass protractors are inside the lid of this plain wooden case lined with pink felt. The handle is missing from the case, and one hinge is broken. The first protractor is hand-divided to single degrees and numbered in both directions by tens from 10 to 180. Underneath the left side of the arc is marked: R. 1/4 F. A plotting scale with a diagonal scale at the left is on the base of the instrument. The second protractor is divided to quarter-degrees and numbered in both directions by tens from 10 to 180. A movable arm with an adjustable blade is attached around the origin point. Two plotting scales are on the base of the instrument. One is marked: Paris.Zoll. The other is marked: Rheinb.Zoll.
Both layers of the case have empty spaces for instruments and instruments that do not fit properly into their spaces, suggesting that parts of the set have been lost or replaced. All of the instruments are brass and steel. The first layer has an L-shaped set square; two screws and a hinge that were originally attached to the case lid; three joint tighteners; and a drawing pen. A pair of dividers has rotating legs with pen and pencil points at the other ends. There are two more pairs of dividers, one with one point removed and stored separately in the case. Two pen points, one pencil point, and a leg extension do not appear to fit the instruments in the case. Bow dividers and three-legged dividers are also on this layer.
The second layer has a narrow (2-1/2" wide) beam compass with a handle; an elliptical trammel; calipers attached to a 6-5/8" rule; and proportional dividers. The rule has scales for German and French inches on one side. This side is also marked: J. D. Weickert in Leipzig. The other side has scales for English inches and for units of 5/16". The second scale is marked: Circum. Verniers are on both edges of the rule, next to the calipers. The proportional dividers are heavily tarnished. One side has scales for polygons and straight lines. That side is also marked: Weickert in Leipzig.
References: Maya Hambly, "Cases of Drawing Instruments," in Drawing Instruments, 1580–1980 (London: Sotheby's, 1988), 150–193; "History of the Felt Factory," http://www.filzfabrik-wurzen.de/de/51/company/history/.
Location
Currently not on view
date made
1783-ca 1850
maker
Weickert, J. D.
ID Number
1984.1070.01
catalog number
1984.1070.01
accession number
1984.1070
This 6-3/8" brass rule unfolds to form a set square. The outer edge of one leg has a centimeter scale numbered by ones from 1 to 16. It is marked: Nelle Mesure. The outer edge of the other leg has a scale for French inches (approximately 1-1/16") numbered by ones from 1 to 5.
Description
This 6-3/8" brass rule unfolds to form a set square. The outer edge of one leg has a centimeter scale numbered by ones from 1 to 16. It is marked: Nelle Mesure. The outer edge of the other leg has a scale for French inches (approximately 1-1/16") numbered by ones from 1 to 5. The first unit is divided into twelfths. The scale is marked: 6 Pouces. This leg has a pinhole for hanging a plumb bob and a rectangular hole with a rounded end (approximately 15/16" long) for viewing the plumb bob. The square has no maker's mark.
For a brief history of squares, see MA.316929. Typically, the legs were marked with scales for measuring lengths. What is unusual about this square is that it has both a traditional French measure and a unit from the newly introduced metric system, which is denoted as a "nouvelle mesure," or "new measure." The metric system was created in France in the 1790s, after the French Revolution of 1789. This suggests a date of about 1800 for the instrument.
Albert Haertlein (1895–1960), who collected this square, graduated with a bachelor's degree in civil engineering from the Massachusetts Institute of Technology in 1918. He served in the engineering corps of the U.S. Army during World War I and taught engineering at Harvard from 1919 until 1959. Haertlein was prominent in the American Society of Civil Engineers.
References: "News From the Classes," Technology Review 21 (1919): 645; Albert Haertlein, Papers, HUG4444, Harvard University Archives, Cambridge, Mass.
Entry 1985.0580.05.
Location
Currently not on view
date made
ca 1800
ID Number
1985.0580.01
accession number
1985.0580
catalog number
333926
This wooden case is covered with black leather and lined with purple velvet. Several circles have been drawn on the top of the lid.
Description
This wooden case is covered with black leather and lined with purple velvet. Several circles have been drawn on the top of the lid. The velvet inside the lid folds out to reveal a 6-3/4" wooden straight edge; a 3-1/2" metal L-shaped square; a 3-3/8" metal semicircular protractor divided to single degrees and numbered by tens from 10 to 170; and a 6" ivory plotting scale with one scalloped end. The plotting scale has diagonal scales at both ends. Above it are scales divided to 1/10" and numbered by ones from 6 to 1, and divided to 1/12" and numbered by tens from 50 to 10. The back of the plotting scale has a scale of chords and scales dividing the inch into 45, 40, 35, 30, 25, and 20 parts.
The bottom of the case has four pairs of German silver and steel dividers. Two pairs have a removable leg and are 5-3/8" long, one pair has fixed legs and is 4-7/8", and one pair has a removable leg and is 3-3/4". A pencil point is a little bit too short for the longest dividers, and a pen point is a little bit too long for the longest dividers. Another pen point and pencil point fit the shortest pair of dividers. A 2-3/4" drawing pen has a very short cylindrical handle. Three empty slots suggest that some of the original instruments in the set are missing. One slot is round for a ceramic cup; compare to 1990.0115.01.
The set was found in the Museum collections in 1979 with objects that suggest an association with Cleveland Abbe (1838–1916), an American engineer, astronomer, and meteorologist who worked for the U.S. Weather Service from 1871 until shortly before his death.
Reference: accession file.
date made
19th century
ID Number
1979.0876.01
catalog number
1979.0876.01
accession number
1979.0876
This polished wood case has a metal plate on the lid and is fastened with brass hooks (one is missing). The case is lined with burgundy silk and velvet.
Description
This polished wood case has a metal plate on the lid and is fastened with brass hooks (one is missing). The case is lined with burgundy silk and velvet. The case and instruments appear to have been assembled separately, because there are more instruments than slots in the case and the styles of the instruments do not match. The case contains:
1) 4-1/4" clear plastic protractor (held in a compartment inside the lid), divided to single degrees and numbered by tens in both directions from 0 to 180.
2) 6-1/4" brass folding square. The outer edge of one leg has a centimeter scale, numbered from 1 to 15, with the first centimeter divided to millimeters. This leg is marked: NLLE MESURE. The outer edge of the other leg has a scale divided to 1-1/16", numbered from 5 to 1, with the first unit divided into twelfths. This leg is marked: ANC MESURE. The scale thus represents a pre-metric French inch. A rectangular hole with a rounded end is cut out of this leg, and the leg has a pinhole for suspending a weight on a string. This instrument is the oldest in the case and probably dates to around 1800.
3) 12" section of a four-fold wooden rule with brass hinge and tip. One side is divided to 1/8" and numbered by ones from 23 to 13. The other side is divided to 1/16" and numbered by ones from 11 to 1. The other half of the rule is missing. Compare to 1990.0099.01 and MA.335275.
4) 4-1/4" German silver extension bar and 3" divider and pen points that do not fit the dividers in the case.
5) 1-18" brass tack that appears to hold ink.
6) 4-1/2" ivory and steel drawing pen with a brass adjusting screw.
7) 7/8" metal joint tightener.
8) 3-3/4" brass and steel dividers with removable divider and pencil points.
9) 4-7/8" German silver and steel fixed-point dividers.
10) 2-5/8" brass and steel pen point that does not fit the dividers in the case.
11) 2" brass pencil point that does not fit the dividers in the case.
12) 3-1/8" curved steel needle point in brass holder; its function is not known.
13) Extra brass adjusting screw, metal plate with one screw, and crudely cut metal circle marked: PEN.
The donors' family was prominent in the history of American science. John William Draper (1811–1882) was a chemist who also made innovations in photography. He had three sons: John C. Draper (1835–1885), who was a physician and chemist; Henry Draper (1837–1882), who was an astronomical photographer; and Daniel Draper (1841–1931), who established the New York Meteorological Observatory in Central Park in 1868 and directed it until 1911.
References: Maya Hambly, Drawing Instruments, 1580–1980 (London: Sotheby's Publications, 1988); Robert S. Harding and Jeffrey L. Tate, "Draper Family Collection, ca. 1826–1936," Archives Center, National Museum of American History, http://amhistory.si.edu/archives/d8121.htm.
Location
Currently not on view
date made
ca 1800-1920
ID Number
MA.335353
accession number
304826
catalog number
335353
This flat brass trapezoid has a rectangular shape cut out of one corner. Beginning at the left side of the rectangle and proceeding counter-clockwise, the corners have Japanese characters for the numbers 9, 4, 3, 5, and 7.
Description
This flat brass trapezoid has a rectangular shape cut out of one corner. Beginning at the left side of the rectangle and proceeding counter-clockwise, the corners have Japanese characters for the numbers 9, 4, 3, 5, and 7. The corners thus were used to draw regular polygons with 9, 4, 3, 5, and 7 sides. (For instance, the angle at the corner with the number 4 is 90°.) According to the accession record, the object was described as a ho kaku-gi (artillery or cannon square) and hoyo ki (artillery scale rule). A user would have made regular polygons in the course of designing fortifications and positioning artillery.
This square was displayed by the Japanese Empire Department of Education at the 1876 Centennial Exposition in Philadelphia. It then was held by the Museum of the U.S. Bureau of Education until it was transferred to the Smithsonian National Museum in 1910. For more information, see MA.261298 and MA.261313.
Location
Currently not on view
date made
before 1876
ID Number
MA.261290
catalog number
261290
accession number
51116
On one side, this 4-3/8" white plastic L-shaped square has scales along its inner edge for reducing yards to the representative fraction (R.F.) of 1:20,000, divided to twenties and numbered by 500s from 0 to 1,000. Scales along its outer edge are for reducing yards to R.F.
Description
On one side, this 4-3/8" white plastic L-shaped square has scales along its inner edge for reducing yards to the representative fraction (R.F.) of 1:20,000, divided to twenties and numbered by 500s from 0 to 1,000. Scales along its outer edge are for reducing yards to R.F. 1:62,500, divided to hundreds and numbered by thousands from 1,000 to 6,000. The end of one leg is marked: U.S.
The other side has scales along its inner edge for reducing meters to R.F. 1:25,000, divided to twenties and numbered by 500s from 0 to 1,500. Scales along its outer edge are for reducing meters to R.F. 1:50,000, divided to fifties and numbered by thousands from 1,000 to 5,000. The end of one leg is marked: U.S. The device, also known as a "coordinate scale," was used by soldiers to compare measurements to notations on a chart in order to aim weapons. Compare to 1977.1141.16. This example was also received with a duplicate square, but the second square was broken and discarded.
According to the accession file, this instrument was made for the U.S. Army by Felsenthal Instrument Company in 1945 as model number FAE-6. The company was the leading supplier of mathematical instruments to the U.S. Army Air Force and the U.S. Navy Bureau of Aeronautics, particularly during World War II (when the firm was known as G. Felsenthal & Sons). After the company ceased operations in approximately 1976, it provided a large sample of its products to the Smithsonian. The lack of any form of the firm's name on this instrument suggests it may actually have been made in the 1960s. For company history, see 1977.1141.02.
Location
Currently not on view
date made
ca 1945
maker
Felsenthal Instrument Co.
ID Number
1977.1141.17
catalog number
336401
accession number
1977.1141
These two instruments are identical. On one side, each 4-3/8" white plastic L-shaped square has scales along its inner edge for reducing yards to the representative fraction (R.F.) of 1:25,000, divided to twenties and numbered by 500s from 0 to 1,500.
Description
These two instruments are identical. On one side, each 4-3/8" white plastic L-shaped square has scales along its inner edge for reducing yards to the representative fraction (R.F.) of 1:25,000, divided to twenties and numbered by 500s from 0 to 1,500. Scales along its outer edge are for reducing yards to R.F. 1:50,000, divided to hundreds and numbered by thousands from 1,000 to 5,000. The end of one leg is marked: U.S. The other leg is marked: G. FELSENTHAL & SONS, INC. (/) MFR. PT. NO. FAE-5 (/) FSN 6675-283-0020. The letters FSN abbreviate "Federal Stock Number."
The other side is printed in red and has scales along its inner edge for reducing meters to R.F. 1:25,000, divided to twenties and numbered by 500s from 0 to 1,500. Scales along its outer edge are for reducing meters to R.F. 1:50,000, divided to fifties and numbered by thousands from 1,000 to 5,000. The end of one leg is marked: U.S. The device, also known as a "coordinate scale," was used by soldiers to compare measurements to notations on a chart in order to aim artillery or to interpret surveillance photographs. Compare to 1977.1141.17.
The Chicago firm that manufactured these squares was known as G. Felsenthal & Sons in the 1940s, G. Felsenthal & Sons, Inc., in the 1950s, and Felsenthal Instrument Co. in the 1960s and 1970s. It made model number FAE-5 for the U.S. Army from World War II through the 1960s. By the late 1960s, the product also came in an aluminum version.
Ben Wharton Rau (1904–1995) and his wife, Margery Felsenthal Rau (1916–2010), arranged the donation of this and many other instruments to the Smithsonian. Margery's grandfather, Gabe Felsenthal, founded the firm in 1899, and her father, Irving (1887–1956), was one of the "Sons" of G. Felsenthal & Sons. Ben worked for the Felsenthals for over three decades. His duties included touring military facilities with a large display of the company's products. He catalogued hundreds of instruments when the company went out of business in 1976. He also held patents on a collapsible film reel, a proportional divider, and a belt buckle assembly.
References: Deborah J. Warner, “Browse by Maker: Felsenthal,” National Museum of American History Physical Sciences Collection: Navigation , http://amhistory.si.edu/navigation/maker.cfm?makerid=173; "Irving G. Felsenthal," Chicago Tribune , February 26, 1956, http://www.susaneking.com/genealogy/showsource.php?sourceID=S01752&tree=GreenebaumSam; Copyright Office, Library of Congress, "Books and Pamphlets," Catalog of Copyright Entries , 3rd ser., 16, part 1, no. 2 (1964): 1392; ); Department of Defense, Employment of U.S. Army Aviation Company (Aerial Surveillance) in Counter-Intelligence Operations (February 9, 1966), D-1–D-2, http://www.dtic.mil/dtic/tr/fulltext/u2/371854.pdf; U.S. Army Artillery and Missile School, Artillery Trends, Instructional Aid No. 41 (Fort Sill, Okla., July 1968), 84, http://sill-www.army.mil/firesbulletin/archives/1968/JUL_1968/JUL_1968_FULL_EDITION.pdf; Ben W. Rau, "Collapsible Film Reel" (U.S. Patent 3,447,759 issued June 3, 1969), "Proportional Divider" (U.S. Patent D214,399 issued June 10, 1969), "Belt Buckle Assembly" (U.S. Patent 3,475,797 issued November 4, 1969.
Location
Currently not on view
date made
1950s
ID Number
1977.1141.16
catalog number
336400
accession number
1977.1141

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