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A discussion from User talk:CyborgTosser:

Hello, CyborgTosser. Noticed your inclusion of "jack rock" as a synonym for caltrop. This puzzled me at first, as I haven't heard this term before, and couldn't find it in any of my dictionatires. Further, I was initially unable to find any Google references that didn't derive from the article. However, I did eventually find CODE OF ORDINANCES CITY OF WASHINGTON, ILLINOIS. These are cirty ordinances for a small town in Illinois. Thus, the term is possibly a local Illinois usage? At present the description makes it appear as if "jack rock" is a common or widely known synonym, which I don't believe is correct. I wondered if you had any additional information on the distribution of this usage so we could clarify the point? Securiger 01:36, 12 May 2004 (UTC)

Well, I found something here: [1] Not excatly the same thing, but along the same lines. I know it's not just a local Illinois thing. I didn't grow up in Illinois and it's the only word I've heard to describe such an item in modern usage. I don't know where I first heard it, but when I mention it to other people, they seem to know what I'm talking about. As a side note, I've always thought of "caltrop" having a military (and usually somewhat archaic) connotation, whereas "jack rock" describes something a criminal might put in the road to slow down police. CyborgTosser 06:35, 18 May 2004 (UTC)

A related term seems to be "star nails", although it doesn't seem to be exactly the same thing. Anyone know? CyborgTosser 06:42, 18 May 2004 (UTC)

"Star nails" are smaller caltrops intended to puncture a vehicle's tires. --Carnildo 07:31, 8 Aug 2004 (UTC)

I added a bit about it being used in labor disputes as well. I know that there are definte POV concerns here. I do remember hearing about jack rocks during the catepillar strike - that they seemed to be a pretty widespread problem. I also seem to remember that not only were tires getting punctured by these devices, but that people were also getting hurt by stepping on them, and that one of the people injured was a reporter. I want to tread lightly here, but if anyone has a better way of exploring this that is more netural than feel free to make changes.
JesseG 21:11, 10 January 2006 (UTC)

Dubious addition[edit]

Caltrops are used inside some atomic bombs to center the uranium or plutonium "pit" inside the spherical tamper. The air gap allows the tamper more time to accelerate, which compresses the pit more tightly and leads to more efficient fission.

I find this to be very unlikely -- for something as highly-engineered as an atom bomb, I'd think they'd use something purpose-built. --Carnildo 05:06, 8 August 2005 (UTC)

It may be that "caltrop" is just the name the engineers have given to a similarly-shaped , similarly-used part. The description of the air-gap is a fact, so there must be some kind of support for the pit (core).
Atlant 12:45, 8 August 2005 (UTC)

Questioning synonyms[edit]

I have never heard of a caltrop being refered to as a dragon's tooth other than the tenuous functional similarity already mentioned in the current article, will the editor who added it please provide a citation. I have deleted it in the meantime.

I was surprised not to find a reference to nail star - that is quite a descriptive name. However, is it really justified?

Jackrock seems prety obscure. However, while discounting web-pages that obviously originate from Wikipedia, in addition to CyborgTosser's reference above[2] I did find a reference to a jackrock as a caltrop here and an authorative looking reference here (Sec. 21-1.4). Gaius Cornelius 17:04, 13 October 2005 (UTC)

Tiswas has recently been added as a synonym. I have googled and found no convincing confirmation. Revert pending cite.

Use in modern day combat?[edit]


I seem to recall reading somewhere (many years ago) that the Air Force would drop caltrops, or at least, something similar, along roads in North Korea during the Korean War. They'd do this around nightfall, then the next morning, bombers would return with bombs to destroy supply trucks that had been backed up when the first vehicle hit the devices and blew out it's tires (this was done before they had any effective means of locating enemy forces in the dark, making night bombing of supply convoys impractical).

Does anyone else remember this? If someone reminds me, I'll look for a cite after I get home tonight, but I'm on my way to work right now.--Raguleader 16:56, 20 November 2006 (UTC)


Rebels manufacture caltrops by the bucket full:

  • C. J. Chivers (3 May 2011). "Hidden Workshops Add to Libyan Rebels' Arsenal". New York Times. p. 2.


I have remnoved the paragraph claiming that the Scots used Caltrops at Bannockburn. The only source to suggest that they were available at Bannockburn is Bower, who claims that they were brought by the English army. Thos caltrops alledgedly 'recovered' from the battlefield seem to have been manufactured by enteroprising Stirlingshire blacksmiths in the 19th century. —Preceding unsigned comment added by (talk) 11:58, 8 January 2010 (UTC)

IIRC, they were used in the English Civil War. —Preceding unsigned comment added by (talk) 21:16, 27 January 2011 (UTC)

The statement in the main article that "there is no evidence that the caltrop was used in either the first Wars of Scottish Independence (1296–1328)" conflicts with the wikipedia article on the Battle of Stirling Bridge, according to which "The heavy cavalry to the north of the river was trapped and cut to pieces (due, in part, to the strewing of caltrops to unseat the cavalry making them easy targets for the Scottish forces),..." — Preceding unsigned comment added by (talk) 11:50, 16 January 2013 (UTC)

How big are they[edit]

From the images, I can not determine how big caltrops are. From the first picture, they look gigantic! I looked for images that demonstrated a caltrops scale, but most were modern and just showed someone using them. Does anyone have a picture with them by say, a penny or ruler? If someone told how big they are, I could theoretically edit in a ruler, if that is permitted for images on articles.TheKing44 (talk) 22:07, 18 December 2014 (UTC)

Exploding caltrops?[edit]

@BabelStone: We've a photo here of "exploding caltrops", or mines. Are you sure the use of "caltrop" here is correct? In modern parlance these would be known as "anti personnel mines". François Robere (talk) 21:15, 26 November 2018 (UTC)

The National Museum of China describes them as "Pottery Caltrops with Gunpowder" in English and as "蒺藜陶弹" ["caltrops pottery bomb"] in Chinese. Another Chinese museum describes them as "Pottery caltrop-shaped gunpowder weapon" in English and as "陶制火蒺藜" ["pottery fire caltrops"] in Chinese. Please feel free to change the description to use the terminology given in reliable sources. BabelStone (talk) 10:28, 27 November 2018 (UTC)

Notes and Queries Reference[edit]

In the 8th series vol II, p 406, 19 November 1892 - mentions a reference to the term being used in The Daily Telegraph in 1882 about the Egyptian war of the time. (talk) 18:02, 21 February 2019 (UTC)