That's a nice PEXTO steel handle, Mary.
PEXTO stands for Peck, Stow & Wilcox Co., which was formed in November 1870 as a merger of Peck, Smith Mfg. Co. , S. Stow Mfg. Co., and Roys & Wlicox Co. They were the maker of the Solid Steel monkey wrench like yours beginning in 1908. The patent was of January 14, 1896 by Robert C. Ellrich. (Source- Ken Cope's American Wrench Makers 1830-1930").