The instructions are printed on it: "Wrap wool with even tension round gauge and cut along groove"- the groove is on the under side.
|From Patons & Baldwins catalogue, 1935.|
The KCG collection also has several booklets of rug designs, from the Patons archive. The earliest, I think, is a Rugcraft booklet. There seem to have been several editions of Rugcraft; this one is later than the one illustrated in the 1935 catalogue, but still shows vaguely Art Deco designs, so possibly dates from the late 1940s.
My mother used to make rugs, up to the 1970s. (My mother-in-law too.) But I don't remember my mother having a rug wool gauge - she bought Readicut kits, with a printed canvas, and bundles of wool already cut to the right length. So no need for a gauge.