Notes: "The Gerber Variable Scale is a tool for interpolation between known points, or for dividing a length x into equally spaced divisions, or for reading values of plotted data. A precision triangular spring has markers on it at 0, 2, 4, 6, 8, and 10, and between those markers there are 20 coils of the spring with every tenth coil painted red, every fifth coil painted green, and all the rest white. Look at the second picture and this will all be much clearer. The slider on the ruler stretches the spring to cover whatever distance you want to interpolate over, up to 10"". "
