About Scioto Works, This book says:

An Ohio Tool Co. imprint for its second-grade line of beechwood planes 1893-1907. It seems ironical that the phrase “extra quality” that appears on the E imprint was used to describe “second grade” planes. The name may have originated from the fact that Ohio Tool Co. was located near the Scioto River in Columbus, Ohio.

Some more information about Ohio/Scioto on the Old Tools Archive