Marked Ohio Tool Co. A major plane manufacturer in Columbus, Ohio in the 19th century and the early 20th century, 1823-1913. This is the 'C' mark in AWP - 5th Edition,  page 276. Rated G+++ and is a user if you are so inclined. Marked '48' and 3/4" on the heel. A nice Dado Plane. Brass depth stop works easily. Many more to follow!