I suspect, but can not prove, that that pattern is a bit older than that. Williams bought the drop forge plant in Chicago from Whitman & Barnes in 1902. W&B wrenches do not have that ribbed pattern, but Union s-wrenches do, and match Willliams almost exactly. Later S-wrenches look like W&B S-wrenches with no ribs....
I don't have evry many samples to compare tho : (
>That is a tool post wrench
Yes and no, many early machines were assembled with square head bolts and nuts, a square end wrench would also be common for Ag machinery...