how well does the wing nut at the top hold 2' arms at a precise adjustment?

Even God uses a compass


I found these interesting as well, an improved version of the drawing compass, the unique design of the legs helps them to hold their adjustment when they are opened widely, and the design of the top portion allows for a sturdy and comfortable one-handed grip. I might make myself a pair of these and see how they work. Recreation based on a carving from an architect's tomb.


Both of these pictures are from this page, http://medievalarchitecturalgeometry.com/Measure%20and%20the%20medieval%20architect.htm, which I would highly recommend to anyone interested in the medieval practice.

see the compass in the bottom right corner.

Note the use of the term compass instead of dividers.
In the middle ages the tool was always called a compass, and it should be called thus whenever it is being used as a drawing tool. The tern dividers came about in the Renaissance when the tool lost its drafting purpose, and was used as a means of dividing (by guess and check) a certain space into equally sized portions. Since we here are not using the tool for dividing, but rather for drawing and measuring, we should call them compasses.