The Gerber Variable Scale, described here, is a thing of beauty and elegance, admirable for its ingenuity and craftsmanship. It is also a “one of a kind” device, or so I thought until my unexpected sighting on eBay of the “Proportional Rule” made by the Data Scaler corporation of Westfield, Massachusetts.

The Datascaler Proportional Rule and the Gerber Variable Scale

This device is a clone — a direct knock-off — of Gerber’s elegant invention. Close inspection shows the small differences in design and manufacturing quality that usually accompany such cloning.

This article examines the details, and uncovers who made this device and under what circumstances.

Check it out!