A monkey
wrench is an
elegant, dynamic tool. The
distance between each jaw can be changed to accommodate different sizes of
nuts. In place of an entire set of
heavy wrenches needed for each size of
nut, this solitary one* can be carried and easily
adapted to
the worker's needs.
In the latter half of the 20th century, several examples of what wrench experts believe to be obvious 17th or 18th century monkey wrenches have been found near Boston, Massachusetts. Their appearance is similar enough to indicate a single smith had produced them. The design of the spanners clearly predates the earliest U.S. wrench patent, that being in 1830. It's highly probable that these wrenches were made in England, and imported to North America in the 17th or 18th century during colonization. This is much earlier than the claim that Charles Moncke had invented the spanner in the mid 19th century, and also precludes the notion that Monk, an American employee of Bemis and Call, invented it.
The ironworks on the Saugus River built in the 17th century provided the demand for this sort of instrument. However, since the discovered spanners aren't signed or dated, it's difficult to tell whether they were produced during the 17th or 18th century. To muddle the waters of history even more, both English and American smiths at the time had the technology and information to possibly produce these wrenches.
This is...
the Great Monkey Wrench Enigma.
*In general. Peculiar jobs require peculiar tools, and therefore more than just a monkey wrench, or a different size of spanner, might be required in nut-turning situations.