Rolling ruler
A rolling ruler is a ruler that contains a cylinder much like a rolling pin inside, thereby enabling it to "roll" along a sheet of paper or other surface where it is being used. A rolling ruler can draw straight, parallel lines, and also has other instruments included, enabling it to do the jobs of a protractor and compass.[1][2]
The modern rolling ruler, with protractor, pivot pin and multiple pin holes serving as fixed length compasses has been patented in the US in 1991 by Wei Wang. [3]
References
- ^ Jack E. Ingels (2003). "Using Drawing Instruments". Landscaping: Principles and Practices. Cengage Learning. p. 11. ISBN 9781401834104.
- ^ Jim Tolpin (2007). "drawing techniques". Measure Twice, Cut Once. Popular Woodworking Books. p. 24. ISBN 9781558708099.
- ^ U.S. patent 5,050,309
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