A page from a machinist’s textbook showing a monkey wrench (left) compared to a Stillson or pipe wrench (right). Both are adjustable wrenches, but the monkey wrench is designed to grip straight surfaces, like hex bolts. The pipe wrench permits some play in the jaws, allowing it to grip circular surfaces, like pipes.
18 May 2021
[19 May 2021: added reference and link to Peter Reitan’s blog; 20 May 2021: added minor clarifications and corrections to the likely/unlikely origins]
A monkey wrench is a type of adjustable wrench or spanner. And to throw a monkey wrench into the machinery is a metaphor for disrupting something, a metaphor of throwing a heavy metal object into machinery. The term originated in Britain, although nowadays it’s primarily found in North American speech and writing.
Why it is called a monkey wrench is uncertain, and there are a number of possibilities, as well as a series of false etymologies based on the name of its supposed inventor. Among the likely origins are that the wrench could be so called because it is a metal object that moves up and down a vertical shaft, not unlike a monkey climbing up and down a tree. Others have observed that the head of the wrench resembles a monkey’s head. (I don’t really see it, but okay. It’s a valid opinion.)
What we do know for sure about the origins is that the term is recorded in England in the early nineteenth century. There is a record of a Richard Fleetwood of Parr and Rainford manufacturing monkey wrenches. He was in business by 1807, although if he was making monkey wrenches as early as that year we don’t know. We do, however, have a definitive use of monkey wrench in the Chester Chronicle of 4 August 1826 in a list of seventeen defendants on trial for various crimes:
13. Andrew Sealion, (27) stabbing David Rogers.
14. William Poole, (50) stealing a candlestick, the property of Daniel Poole.
15. William Darlington, (60) stealing a monkey wrench, the property of the Canal Company.
16. John Phelan, (17) stealing £70. 7s. 10d. the monies of John Finchett-Maddock.
Monkey wrench appears in North America by 1838. The following advertisement appears in the Natchez Daily Courier (Mississippi) on 20 September 1838:
HARDWARE.
CARPENTERS knob-locks, flush bolts, cast butts, monkey wrenches, hand-cuffs, Salters Patent Spring balances; with a large and general assortment of Carpenters tools for sale by
sept 20 PATTERSON & WISWALL
The following odd legal notice appears in the New York Evening Post on 31 May 1839, announcing a lawsuit having been filed against an assortment of property that includes a monkey wrench. Under U.S. law it is possible to sue property, especially when the ownership of the property is to be decided by the court. In the notice, the word libel is being used to mean a written complaint, not an accusation of defamation:
Whereas a libel hath been filed in the District Court of the United States for the Southern District of New York, on the 24th day of May, A.D. 1839, by Gabriel Dissossway, Libellant, on behalf of himself and others, the crew of the schooner Elisha Ruckman, against 5 Spanish hides, 1 barrel of brown sugar, 2 harness casks, 7 sails[?], 14 yards of canvass, ship’s side steps, side skids, 18 fathom square sail halyard, 10 pounds of rope yarn, 8 pounds spun yarn, 1 keg, 1 tea cannister, 1 oil can, 2 jugs of oil, 12 purchase blocks, 2 barrels, 1 monkey wrench, 2 ship’s scrapers, shovel, a part of the cargo of the schooner La Bruce[?].
And whereas the substance of the said libel is, that the Libellant, with others of the crew of the said schooner Elisha Ruckman, on or about the 21st of April 1839, on the high seas fell on[?] with the schooner La Bruce[?], totally abandoned and derelict, that they then boarded her and towed her into port, with the articles before enumerated, and praying that said articles may be condemned and sold to pay the Libellants a reasonable salvage for the same.
And we get a formal definition in an 1858 Dictionary of Trade Products:
MONKEY-WRENCH, a spanner with a moveable jaw.
One explanation for the term that appears as a suggestion in some major dictionaries is that monkey has been used to refer to menial laborers since the seventeenth century, so the wrench could be one used by such laborers. This, however, is somewhat doubtful, as these instances are few, and invariably refer to jobs commonly performed by children (e.g., powder monkey), who can be likened to monkeys.
It is often claimed that the monkey wrench is named after its inventor, either a Charles Moncke or any number of others with a similar name. There is no evidence supporting any of these claims, and in all the claims that I have seen, the inventor is said to be an American and to have invented it on a date after we find the term in print. Given the wide variety of claims, the fact that the proffered names are invariably American when monkey wrench first appears in Britain, and the claimed invention sometimes coming decades after the actual invention, we can confidently dismiss these claims as false.
Another false etymology is that monkey wrench is a racial slur because it was invented by former heavyweight boxing champion Jack Johnson, a Black man. Johnson did patent a type of wrench in 1922, but as we’ve seen, this was about a century after the wrench’s invention. There is no evidence linking monkey wrench to the racial slur monkey.
As for throwing a monkey wrench into the machinery, that idiom is an Americanism that appears in the late nineteenth century. The earliest use I have found is ambiguous, in that it is not clear whether the use is metaphorical or if an actual monkey wrench were dropped into a printing press. The context is the Boston mayoral election of 1884. From the Marion Daily Star of 9 October 1889:
M. J. Kiley, the Boston Democrat who was to print ballots for both sides in the election when O’Brien was first made mayor, but who dropped a monkey wrench into the press before the Republican ballots were run off may be there.
It appears again in the San Francisco Chronicle of 6 July 1892. Again, the context is that of politics, but here the use is clearly metaphorical, the machinery being that of the legislative process:
Bland’s action in insisting upon amending the Stewart bill has been severely criticised. He is charged with occupying the position of the man who threw a monkey-wrench into a threshing machine because he was not allowed to feed it. The trouble with Bland seems to be that it is Stewart’s bill and not his. He wants all the fame, even if he jeopardizes the cause in which he proposes to lead.
The British version, throw a spanner into, appears later, although that co-location of words referring to a literal throwing of a wrench appears a bit earlier. In a London Times article from 27 April 1879 about an explosion at Woolrich Arsenal:
An inquest was held at Woolrich on Tuesday relative to the death of Johnson, a lad employed in the cartridge factory of the Royal Arsenal, who died on Monday from injuries received through an explosion on Saturday. The lad had stated after the accident that it was caused by his throwing a spanner into a box in the workshop, and that something in the box immediately exploded; but the evidence pointed to a different conclusion.
The metaphorical use of the British version is recorded in a 1925 story by Owen Collinson:
Hugh sat and gazed with outraged eyes at this wrecker of his life. A vision of Joyce came to him, and his heart sank as he told himself for the thousandth time that she was lost to him for ever. And Wilfred had done it—this pale little man who lad meddled with forces unimaginably beyond his comprehension, like some small boy light-heartedly throwing a spanner into a mighty dynamo and causing immense disruption.
Peter Jensen Brown’s (a.k.a. Peter Reitan) Early Sports and Pop Culture History Blog has more on monkey wrenches, including some other plausible (but still unsupported with evidence) hypotheses as to why they are called that.
Sources:
Advertisement. Natchez Daily Courier (Mississippi), 20 September 1838. Gale Primary Sources: Nineteenth Century U.S. Newspapers.
“Chester Summer Sessions.” Chester Chronicle (England), 4 August 1826, 3. Gale Primary Sources: British Library Newspapers.
Collinson, Owen. “The Perfect Friend.” Sunday Pictorial (London), 8 March 1925, 16. Gale Primary Sources: Mirror Historical Archive.
Dane, E. Surrey. Peter Stubs and the Lancashire Hand Tool Industry. Altrincham, UK: John Sherratt and Son, 1973, 219.
Evon, Dan. “Did Jack Johnson Invent the Monkey Wrench?” Snopes.com, 14 December 2015.
“Explosion at the Woolrich Arsenal.” Sunday Times (London), 27 April 1879, 5. Gale Primary Sources: Sunday Times Historical Archive.
Green’s Dictionary of Slang, 2021, s.v. monkey, v.
“Our New York Letter.” Marion Daily Star (Ohio), 9 October 1889, 3.
Oxford English Dictionary, third edition, June 2019, s.v. monkey wrench, n.; March 2021, s.v. monkey, n., monkey, v.
“Silver Men United.” San Francisco Chronicle, 6 July 1892, 3. ProQuest Historical Newspapers.
Simmonds, P. L. A Dictionary of Trade Products. London: G. Routledge, 1858, 251. HathiTrust Digital Archive.
Staten, Vince. Did Monkeys Invent the Monkey Wrench. New York: Touchstone, 1996, 41–43.
Stimpson, George. A Book About a Thousand Things. New York: Harper and Brothers, 1946, 287. HathiTrust Digital Archive.
Tréguer, Pascal. “Origin of ‘Throw a Monkey Wrench Into’: Threshing Machines.” Wordhistories.net, 25 May 2018.
Waddell, Wm. Coventry H., U.S. Marshal. “Southern District of New York.” Evening Post (New York), 31 May 1839, 2. Readex: America’s Historical Newspapers.
Image credit: Rogers, William. The Progressive Machinist: A Practical and Educational Treatise, with Illustrations. New York: Theodore Audel, 1903, 172. HathiTrust Digital Archive. Public domain image.