In his book American Wood Type, Rob Roy Kelly showed 3 different designs for Quarter Rounds and attributed them to the Hamilton Manufacturing Company, along with the date 1892. Because I don’t have access to more than a handful of specimens, I can only guess that the date refers to the Hamilton Mfg. Co.’s Wood Type & Borders from 1892 (see the comprehensive Hand List of Specimen Books on the Rob Roy Kelly American Wood Type Collection website). Update: see also David Shields’ comment about the origins of what Page called “Japanese Corners.”
The very shallow counters in the ornamental design indicate that the face has been die stamped, while the deeper shoulder has been cleared away with a router.