Cross-shaped slider 1 has guides perpendicular to each other and moves along fixed guides p. Link 3 moves in slider 1 and is connected by turning pair K to link 4. Link 4 moves in slider 5 which is connected by turning pair A to slider 1. Roller 2 has a sharp-edged rim and rotates about axis a-a. When slider 1 moves along axis x-x of guide p, roller 2, cutting into the surface of the drawing with its sharp edge, moves during each instant along straight line AK. Link 3 moves in a direction perpendicular to axis x-x. The envelope of the successive positions of straight line AK is a logarithmic or exponential curve with the equation y=ke^(ax) where a=A͞͞B , k = value of ordinate y at x=0, e = base of natural logarithms.
$1232$LG,Ge$