Compasses

A collection of dividers and compasses in the Division of Medicine and Science's Mathematics collection.

One characteristic of the compasses in the collection is the variety of ornamentation molded into their metal parts. More often than the instruments on the other pages, compasses were manufactured in the United States, and Americans received patents for adding innovations to the instrument. Several of the objects below were used in schools, and some were even designed to prevent schoolchildren from poking themselves and each other. This page also contains spare parts for compasses.

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Safe-T Circle Perfect Compass

This instrument consists of two orange molded plastic discs held together by a metal screw and a plastic bolt, a blue pencil, and a blue plastic stylus with a metal point. The pencil and the stylus fit between the discs on opposite sides of the screw.
Description
This instrument consists of two orange molded plastic discs held together by a metal screw and a plastic bolt, a blue pencil, and a blue plastic stylus with a metal point. The pencil and the stylus fit between the discs on opposite sides of the screw. The user adjusts the screw and stylus to the desired diameter for the circle, according to a scale from zero to ten inches on the front of the instrument or a scale from zero to 24 centimeters on the back of the instrument. The compass is somewhat flimsy to operate.
The front of the disc is marked: CIRCLE™ (/) PERFECT (/) #45748. The back is also marked: pat. pend. The stylus is marked: CHINA. A blue and orange cardboard backing was held to the instrument by the screw. The back of the card has instructions and is marked: Pat. Pend. (/) Made in China (/) SAFE-T PRODUCTS™, Inc. (/) P.O. Box 692 (/) LaGrange, IL 60625 [sic]. As with other Safe-T items in the collections, this model number was used for distribution to retail stores. Extra Measures, the company associated with Safe-T Products, sold this compass through its own catalog as model number 45743 for $2.25 around 2000. For company information, see 2000.0160.04.
References: Bruce Stoneberg, "Circle Compass" (U.S. Patent 5,630,278 issued May 20, 1997); accession file.
Location
Currently not on view
date made
1997-2000
maker
Safe-T Products, Inc.
ID Number
2000.0160.07
accession number
2000.0160
catalog number
2000.0160.07

Safe-T 45762 Blackboard Compass

This is an oversized form of the Safe-T Compass (1998.0033.03), for use at a blackboard or dry erase board. It is a white plastic wedge-shaped instrument, with a rotating clear plastic disc set inside the wide end of the wedge.
Description
This is an oversized form of the Safe-T Compass (1998.0033.03), for use at a blackboard or dry erase board. It is a white plastic wedge-shaped instrument, with a rotating clear plastic disc set inside the wide end of the wedge. Both long edges of the wedge have a row of 9 circular holes. The holes are marked for the radius of various circles, from 1" to 5". To draw a large circle, a marker or piece of chalk is placed in the desired hole and the instrument is rotated while the user holds the disc. Note that the circle radii are those that may be drawn with the pocket-sized version of the instrument. This compass actually draws circles with radii from 3" to 15". One long edge of the wedge has a scale marked for four inches, divided to 16ths of an inch. The other edge has a scale marked for ten centimeters, divided to millimeters. Both scales are oversized.
Seven holes are in the disc. A piece of black rubber in the center hole attaches the instrument more securely to the blackboard. To draw a small circle of up to 3/8" radius, a marker or piece of chalk is placed in the desired hole and used to rotate the disc, while the wedge is held in place. Again, this instrument actually draws larger circles. The wedge is marked: SAFE-T (/) COMPASS® (/) Bensenville, IL 60106-0316 (/) #45762 Pat. #5,615,485. It is also marked: π = 3.1416 (/) A = πr2 (/) C = πd. The donor applied for the patent listed on this instrument in 1995 and simultaneously assigned it to Safe-T Products, Inc. A company catalog in the accession file indicates the compass sold for $18.95 around 2000.
According to the donor, the Safe-T compass, invented by Jack Kettlestrings of Naperville, Ill., was the first product of Safe-T Products, Inc., and Extra Measures, Inc. These related companies were established in the northwest Chicago suburbs in 1992 and 1997, respectively, to sell drawing instruments that were safe for children. For instance, as the donor noted, the compass is too wide to be swallowed, and the plastic bends, but does not break. This concern for safety is reflected in numerous products of the time. In 2006 and 2007, Safe-T was absorbed into Classroom Products Warehouse, and Extra Measures was taken over by Learning Resources, Inc. These firms were next-door neighbors in Vernon Hills, Ill., as of 2012.
References: Accession file; Bruce Stoneberg, "Instruments for Drawing Circles" (U.S. Patent 5,615,485 issued April 1, 1997); "Corporate and Limited Liability Company Name Search," Office of the Secretary of State for the State of Illinois, http://www.ilsos.gov/corporatellc/CorporateLlcController.
Location
Currently not on view
date made
before 2000
maker
Safe-T Products, Inc.
ID Number
2000.0160.04
accession number
2000.0160
catalog number
2000.0160.04

Safe-T 45700 Bullseye Compass

Like 2000.0160.06, this red and white plastic instrument combines a ruler, a protractor, and a compass. Unlike 2000.0160.06, this object is smaller, white instead of clear, and uses a slide instead of rows of holes for setting the radius of a circle.
Description
Like 2000.0160.06, this red and white plastic instrument combines a ruler, a protractor, and a compass. Unlike 2000.0160.06, this object is smaller, white instead of clear, and uses a slide instead of rows of holes for setting the radius of a circle. The semicircular (protractor) end is wider than the rectangular part of the instrument. It is marked in 15-degree increments in both directions, from 15 to 165 degrees, and divided to units of five degrees.
Inside the arc is a small rotating disc. The rectangular ruler has a groove down its center that carries a sliding red plastic piece with two holes in it. This piece can be set anywhere along the scales on the ruler, giving the distance from the center of the small disc. Placing a writing implement in one of the holes and rotating the ruler while keeping the disc fixed gives a circle of the radius set. One of the long edges has a ruler 12 centimeters long, divided to millimeters. The other edge has a five-inch ruler, divided to 16ths of an inch.
The back of the instrument is marked: U.S.Pat. # 5,615,485 (/) Other Pats. Pend. The back of the slide is marked: MADE (/) IN CHINA. The Bullseye Compass was introduced in 2000 and retailed for $1.99 in 2012.
References: Learning Resources online catalog (accessed October 22, 2012); Ho Chan, "Adjustable Compass with Ruler and Protractor" (U.S. Design Patent 411,959 issued July 13, 1999); J. Bruce Stoneberg, "Drawing Tool" (U.S. Patent 6,606,796 issued August 19, 2003); accession file.
Location
Currently not on view
date made
2000
maker
Safe-T Products, Inc.
ID Number
2000.0160.08
accession number
2000.0160
catalog number
2000.0160.08

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