A geometric construction done with a movable Compass alone. All constructions possible with a Compass and
Straightedge are possible with a *movable* Compass alone, as was proved by Mascheroni (1797). Mascheroni's
results are now known to have been anticipated largely by Mohr (1672).

**References**

Ball, W. W. R. and Coxeter, H. S. M. *Mathematical Recreations and Essays, 13th ed.*
New York: Dover, pp. 96-97, 1987.

Bogomolny, A. ``Geometric Constructions with the Compass Alone.'' http://www.cut-the-knot.com/do_you_know/compass.html.

Courant, R. and Robbins, H. ``Constructions with Other Tools. Mascheroni Constructions with Compass Alone.'' §3.5 in
*What is Mathematics?: An Elementary Approach to Ideas and Methods, 2nd ed.*
Oxford, England: Oxford University Press, pp. 146-158, 1996.

Dörrie, H. ``Mascheroni's Compass Problem.'' §33 in
*100 Great Problems of Elementary Mathematics: Their History and Solutions.* New York: Dover, pp. 160-164, 1965.

Gardner, M. ``Mascheroni Constructions.'' Ch. 17 in
*Mathematical Circus: More Puzzles, Games, Paradoxes and Other Mathematical Entertainments from Scientific American.*
New York: Knopf, pp. 216-231, 1979.

Mascheroni, L. *Geometry of Compass.* Pavia, Italy, 1797.

Mohr, G. *Euclides Danicus.* Amsterdam, Netherlands, 1672.

© 1996-9

1999-05-26