Promotional fliers for The Butterfield Hem Finder, Butterfield Mfg. Co, Fostoria, Ohio.
This hem gauge is so grand, it’s called a “machine”. A lady, in this shown version, stands on the platform, and her skirts are draped over the ring, which is then raised to the desired length, allowing for the fitter to very easily mark a chalk circle all the way around the skirt, right on the fabric. Based on patent info and illustration, this dates to La Belle Époque, or circa 1890’s to 1910’s.
For more information on this, see my article at Collectors' Quest.