These French carriage wrenches come in all sizes. I have 3 of them: a huge one(17.5 inches long) I found at an antique store in Chadds Ford, PA; a small one(6.25 inches long) I found at a flea market in New Castle, DE; and a medium-sized one (8.25 inches long) I found one Sunday at the Schauman Kai flea market in Frankfurt, Germany (WWII booty? a Rhineland artifact?). It's my belief that the French made these wrenches for a period of up to a century, ending in the late 19th or the early 20th centuries.
The largest of the wrenches has a steel cap over the end of the handle, and it is secured by a square nut; the other two wrenches are secured by a round nut with two opposing slots in the perimeter of that nut. I wonder if the nature of the securing nut correlates to the age of one of these wrenches?