An early scale used for the presentation of resistivity logs. The scale has two parts, equally divided about a midpoint. The left part is linear in resistivity, for example 0 on the left edge to 50 ohm-m at the midpoint. The right part is linear in conductivity, from 0 on the right to 1/50 = 20 mS/m at the midpoint. In this way, it was possible to display the complete range of resistivity in one track. It was subsequently replaced by the logarithmic scale.