B-L Wrench Company (Boston, MA) - We believe the "B-L" stands for Baston - Leavitt. Organized ca. 1903. An article appearing in a 1904 edition of Domestic Engineering and the Journal of Mechanical Contracting announces the formation of the E. K. Baston Co. to take over the business of the B-L Wrench Company.
The B-L wrench is based on Patent #765,583 by Claude F. Leavitt, and assigned to Ephraim K. Baston on 7/19/1904.
Advertisement from The Plumbers Trade Journal - January 1, 1908.
Article from 1903 explaining the B L Wrench.