An aside on this: the machinist square with B [dot] S logo appears as early as the 1905 catalog.
However, the same logo with the words "TRADE MARK" underneath first shows up (that I can find) in illustrations in the 1952 catalog. In the 1954 catalog, new illustrations of the logo with "TRADE MARK" no longer have the dot between "B" and "S".
The 1959 USPTO
trademark registration, with no dot, claims a "First Use Anywhere" date of July 28, 1955.
However, the 1967 USPTO
trademark registration for a version with shaded letters and no dot claims a "First Use Anywhere" of 1897. It also claims ownership of the related registration
56130, which (if you look to the
registration certificate) was filed in May 18, 1905. Unfortunately, the "accompanying drawing" was not scanned, and I actually need to leave the keyboard at some point today.
Short version: logo was used since about the first of January 1897, logo with "TRADE MARK" underneath it appears to date from 1950s?