Wrenches have existed for many centuries, but saw a great blossoming in development starting in the 19th century.
The first patent for a wrench was granted in 1835 to Solymon Merrick.
Today, size is usually determined by dimensions such as across-flats distance (inscribed-hexagon size).
In the 19th and early 20th centuries, it was common to define the nominal size of the wrench according to the nominal size of the screw thread that it was meant to be used on. This is seldom, if ever, done any more.
Clever design…I’ll take 2, Thanks.
That pic’s kinda creepy man
And he humbly bowed his head in shame knowing these wrenches were more than enough to size him up as a man.