Gerber Scientific Instrument Variable Scale TP007200B

Description

This rectangular aluminum instrument has a scale of reciprocal inches, unevenly divided and labeled RI; a scale of equal parts, labeled I and numbered by ones from 1 to 10 and by tens from 15 to 95; and a logarithmic scale labeled L10. An aluminum slide on top of the scales has a plastic indicator with a hairline. The slide is attached to a spring that expands and contracts within a clear plastic housing above the scales. It has 103 coils, 100 of which are calibrated. Every tenth coil is colored red, every fifth coil is blue-green, and the rest are white. A second spring is numbered by twos from 0 to 10.