US Patent 7373734 Linear proportioner

A linear proportioner including a logarithmic mechanism to be used for transferring linear dimensions from an existing drawing, picture or actual scene to a new drawing or artist medium. An elongated assembly provides two indicators (one fixed and one variable) as reference pointers, two indicators (one fixed and one variable) for object pointers and an adjustment knob which, when rotated, moves the variable indicators synchronously and proportionally. By depressing the knob when transferring the first object dimension, the proportion ratio (transparent to the operator) is automatically set for subsequent dimension transfers.