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Article stated that fæthm meant bosom. I found two sources saying it meant outstretched arms so I changed this. Oska 11:30, Dec 20, 2004 (UTC)

I don't know whether this was one of them but if not, then it's another. Jimp 2Nov05
In the singular it was indeed bosom. It's the plural that meant outstretched arms and has come down to us as the measurement. Old Moonraker 15:13, 21 October 2006 (UTC)
The Old English word can be translated in various ways, e.g. bosom, outstretched arms, embrace, grasp, protection, expanse, abyss. In each case, the sense may be literal or figurative or somewhere in between, depending on the context:
(Note: The letters þ and ð were used interchangeably by Old English scribes for the dental fricative sounds which we represent with th in Modern English.)
The OED does indeed claim a distinction in Old English between sg. bosom and pl. the embracing arms. But both examples it cites of the latter sense refer to the outstretched arms of more than one person. The entry in Bosworth & Toller, at the link above, cites examples of both singular and plural with the sense embrace (sg. on fremdes fæðm, pl. of brimes fæðmum), as well as examples of both singular and plural under the sense lap, bosom, breast (sg. on bates fæðm, pl. to fæder fæðmum). But in some cases, especially where the meaning is figurative, this distinction between bosom or embrace may be more or less arbitrary, or at least open to interpretation. As a measure of length, the Old English Corpus Glossary (c. 800) glosses Latin passus as sg. faeðm. This is cited by the OED under the sense "The length covered by the outstretched arms, including the hands to the tip of the longest finger; hence, a definite measure of 6 feet."
Even if the OED is correct, it would be misleading to say that the name derives from the Old English word fæthm (plural) meaning 'outstretched arms' , since fæðm is grammatically singular.

-- Dependent Variable.

Why is depth measured in fathoms?[edit]

As an English man born in England in 1954 and brought up in England, I have been aware since Primary School that depths of water were measured in fathoms. However no-one has ever told me why this should be; why do we measure depth in fathoms?

In those pre-metrication days length and distance were generically expressed in combinations of inches, feet, yards and miles. Horse races were measured in furlongs, but that was about the only unusual measure in use ...apart from the fathom. It struck me as perverse that fathoms should still be in common use. There must have been a important reason.

The (to me) obvious answer occurred to me a few years ago after mowing my back lawn. As I coiled the mower cable I realised I was forming each loop of the coil from the length of cable between my two outstretched arms – my personal ‘’fathom’’. I was also aware how easy this coiling action was. I’m not particularly fit, but my left hand, (holding the growing coil) swung easily back and forward like a pendulum, balancing the action of my right hand. As my left hand stretched out, it pulled the next length of cable through my right hand (“measuring�? the “fathom�?) and as my two hands came together I made another coil. How long is my cable? Easy! Count the coils; it’s that many fathoms! How long is a rope stowed aboard ship? Count the coils; it’s that many fathoms!

This, to me, seems an obvious explanation of why a fathom is a measure of length corresponding to the outstretched arms (see wiktionary), rather than being an mere defintion, but I’ve never heard anyone give it as a reason and I've never come across it in any book, not that I have looked too hard! Does any Wikipedian know of an authority for this idea other than me in my back garden?

Further thoughts:

  • If I am correct, the determining factor for using fathoms as a unit of measurement is not that you’re at sea but that you are using rope. Have fathoms been used anywhere other than at sea because people were measuring with coils of rope? The article says fathoms were used in Cornish mines – is this the reason?
Not just in Cornwall. It was used throughout the UK. See Scottish example at --ML5 14:44, 28 May 2007 (UTC)
Found a link for "throughout UK" and added it to ML5's correction — thanks for putting me right! --Old Moonraker 15:33, 28 May 2007 (UTC)
  • The article list units of similar length from other cultures. I wonder if any of those relate closely to coiling rope?
  • This also seems to tie in with the “encircling�?, “embracing�? meaning of fathom (see wiktionary again). It seems very reasonable for a circular loop of rope formed this way to be called, effectively, “an embrace�? of rope.

Brother Francis 12:20, 15 April 2007 (UTC)

It's an interesting theory, but unfortunately, without an authoritative cite, it is mere speculation, and shouldn't be in this article. Rhialto 13:40, 15 April 2007 (UTC)
I agree and so I hope there is someone out there who is able to cite a reference. In time, because that's how some coils of rope are (there's nothing speculative about the way I coil my mower cable!), I would consider proposing text that addresed the matter for this discussion to consider ... but before I do that I hope for a citation. Brother Francis 23:22, 15 April 2007 (UTC)
It's because depths were originally measured using a lead sinker attached to a line. The lead was dropped over the side of the ship and allowed to bottom. The line was then hauled-in manually using the distance between the outstretched arms as a measure and the number of 'arms'-used counted. This gave the depth in measures of approximately six feet. When the person doing the sounding was lax or lazy he wouldn't wait for the sinker to bottom and would haul-in prematurely giving inaccurate readings - hence the term swinging the lead. Ian Dunster (talk) 10:05, 13 May 2008 (UTC)
Ian Dunster's suggestion, of measuring rope as it's hauled in by counting the number of "arms", is highly persuasive: does anybody have a WP:SOURCE so it can be put in? --Old Moonraker (talk) 20:25, 13 May 2008 (UTC)
I included a description of this in the article back in 2004. It has been removed in the interim period. Oska (talk) 09:34, 28 May 2008 (UTC)


I can't think of a better wording right now, or I'd fix it. But reading this article, mainly about a maritime measurement, on being told that it was used for the depth of mines, I naturally assumed the military kind of mine. It was only when, out of curiosity, I followed the link, that I found it concerned mineral extraction! —Preceding unsigned comment added by (talk) 03:01, 23 February 2008 (UTC)

Ouch—good catch! Now fixed, using your terminology. Thanks. --Old Moonraker (talk) 22:40, 24 February 2008 (UTC)

Other fathoms and similar units of length[edit]

where do the differing numbers for some of the other fathoms come from? and is the implied accuracy of some of them really justified?Rody1990 (talk) 02:15, 2 April 2010 (UTC)

No, it looks like WP:NOR. For example, in what context (since Moses, that is) has there ever been a comparison between measuring the height of horses using hands and the fathom? Nearly all of these could go, leaving just the ones that are actually used, for example metres and feet on maritime charts, at a realistic level of precision. --Old Moonraker (talk) 07:44, 2 April 2010 (UTC)
going ahead and deleting the section as several of the indicated numbers seem false, and there seems little justification of their inclusion anyway (most of these are simply the same unit, but translated and somehow given a different value perhaps due to WP:NOR). if you feel this is wrong at least justify all the numbers used.Rody1990 (talk) 11:18, 13 January 2011 (UTC)

Abbreviation "ftm"[edit]

I didn't want to splatter the lede paragraph with a {{citation needed}} link, so I'm asking here: What's the source for this, please? The American Heritage Abbreviations Dictionary (Houghton Mifflin) has "fm.". --Old Moonraker (talk) 08:14, 27 June 2010 (UTC)

The American Heritage Abbreviations Dictionary is obviously wrong. "fm" is the SI symbol for femtometres.— Preceding unsigned comment added by (talkcontribs) 12:38, 4 February 2012‎ (UTC)
OK, tried a little harder and found some. Not one of them agrees with another (e.g. fth, fthm, fat, and fm) and one authoritative publication from OUP can't make up its mind: it offers two, on different pages. So, there doesn't seem to be a definitive one. Thanks for the nudge, and I'll shut up now. --Old Moonraker (talk) 13:38, 4 February 2012 (UTC)
To say that The American Heritage Abbreviations Dictionary is obviously wrong because "fm" is also the SI symbol for femtometres makes no sense. Look at any dictionary of English abbreviations: nearly all two- and three-letter abbreviations have multiple meanings, depending on the context. The letters "fm" can mean Frequency Modulation, the Federated States of Micronesia, Family Medicine, etc. Zyxwv99 (talk) 15:55, 11 February 2012 (UTC)

The American Practical Navigator (Bowditch)lists fm(s) Fathom(s) as the proper abbreviation (Page 851). "Bowditch" is certainly considered a authoritative publication. — Preceding unsigned comment added by (talk) 17:24, 24 July 2013 (UTC)

WP:BOLD I removed the abbreviations: there was just one ('ftm') at the beginning, and someone had added a list of (some of the) possible abbreviations. If there is no standard abbreviation -- which the above discussion shows to be the case -- then it is wrong to list one, and there is no value in a shopping list. Any word in the English language can be abbreviated where necessary and appropriate, in any reasonable way. Imaginatorium (talk) 17:17, 10 March 2015 (UTC)

Thanks for removing ftm, but now there is a problem with {{convert}}. In the past, convert used "acre" as the symbol for acre, and "fathom" as the symbol for fathom, and so on for a few other similar units. The space saved by showing "ftm" rather than "fathom" is negligible, particularly given that the units rarely appear in articles, and "ftm" would have very little meaning to most readers today. Unfortunately, convert was changed with this edit to show "ftm" as the symbol for fathom, with the result that several articles are now unnecessarily obscure. For example, Atlantic Ocean#Geography has:
The average depth of the Atlantic with its adjacent seas, is 3,339 metres (1,826 fathoms; 10,955 ft)
The change to the symbol caught me at a delicate time because I try to not OWN convert too much (I wrote its module), so I took a very neutral line when raising the issue at convert's talk. I actually think "ftm" is very unhelpful in 2015, but when I checked this article, it assured me that "ftm" was correct! It was this edit on 27 June 2010 which added "'(abbreviation: ftm)" and it is bogus because there is no official symbol for a unit like fathom. Assuming we can get agreement here, I should revert the change to convert when I next update it, perhaps in a few weeks. Johnuniq (talk) 10:43, 11 March 2015 (UTC)

Dubious arithmetic[edit]

The section "On land" seems to include obvious errors: the expression "six foot square" means a square of side 6 ft, so 36 sq. ft., not 6 sq. ft. I also notice that the claim about referring to amounts of wood in Britain should be past tense: the quote cited in the SOED is from 1577! And I am removing the bit about Hungary: almost exactly the same claim could be made about Japan (I happen to know), and there really is not coherent point in including such random factoids.

I'm also puzzled about "full fathom five" (see the catchphrase entry): generally it seems to be assumed that this means "five fathoms", i.e. 30 ft., but "deep six" is said to mean being buried in 6 fathoms of water, yet one fathom (i.e. 5 or 6 ft.) is said to be the burial depth on land. I can't find any authoritative-looking statement on this, but I would have guessed that if anything "full fathom five" meant a full fathom of five feet. Imaginatorium (talk) 05:37, 3 September 2016 (UTC)

I'm an obscure unit geek, and this is literally the first time ever I have seen anyone suggest that a fathom might be exactly five feet. Definitions I have seen are either exactly six feet or exactly 6.08 feet. Rhialto (talk) 08:33, 5 September 2016 (UTC)