.... all the different variants of "S" handle adjustables following this design. Seems I am always finding some marked just a bit different than others I had seen before.
The adjustable "S" handles were around for a long time -- if you include the crook handle British "Clyburn spanners" which go back to 1842 -- 0therwise the U.S. ones start roughly Civil War but did not really take off until the 1880s. With marking variations, combinations of wrought iron, malleable iron, drop forged steel, cast steel, etc. and then throw in the nut wrench styles, pipe wrench styles, and "convertible" where the wrench body could take an adjustable jaw for either pipe or nuts ...
As to patents -- beside the British "CLYBURN SPANNER" from 1842, U.S. manufacture mostly went ahead without patents. According to Cope, the GREENE RIFLE WORKS was advertising "Patent Adjustable S Wrenches" in 1867 -- but the patent they refer to was probably related to the adjustment means & not the handle shape.
Scrolling through Schockley:
R.S. Stenton had "S" handle monkey wrench patents in 1866 / 1867 (# 56,628 & 60,801).
G.C. Taft April 27, 1869 patent 89,517 is an adjustable "S" as is 108,738 of Oct. 25, 1870.