Given the circumference of a circle, construct its center using the compass alone. 

Construct the Peaucellier's linkage using the compass alone.  
Given a circle and two points, construct the points of intersection of the line joining the two points with the circle using the compass alone.  
Construct the vertices of a regular pentagon using the compass alone. 
Construct the linkage to draw an ellipse using the compass alone. 
Construct the Bowditch Curve using the compass alone. 
Construct the ellipse and the hyperbola using the compass alone.  
Construct the parabola using the compass alone. 