On September 13, 1870, U.S. Patent No. 107,304 title “Wrench” issued to Daniel C. Stillson (1826-1899), a mechanic at the Walworth Company, in Cambridge, Massachusetts:

This was improvement to the original pipe wrench that Stillson patented on October 12, 1869, (U.S. Patent No. 95,744):

In some places pipe wrenches are still called “Stillsons.”

Stillson’s pipe wrench is often confused with a monkey wrench, but (1) a pipe wrench usually has serrated or toothed jaws; (2) the upper jaw moves on a pipe wrench, while it is the lower jaw that moves on a monkey wrench; (3) the handle of a monkey wrench is usually round and made of wood; and (4) while monkey wrenches are more versatile, pipe wrenches (because of the serrated jas, grip pipes better.