2888: US Survey Foot

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US Survey Foot

Title text: Subway refuses to answer my questions about whether it's an International Footlong or a US Survey Footlong. A milligram of sandwich is at stake!

Explanation

This explanation may be incomplete or incorrect: Created by a 610 US-SURVEY-NANOMETER MONKEY - Please change this comment when editing this page. Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks.

This comic pokes fun at a difference in length of the US Survey Foot and the International Foot. After Carl Edvard Johansson's gauge blocks in 1912 led to an international agreement in 1959, the foot has been defined to be exactly 0.3048 metres, whilst the US survey foot is defined as 1200/3937 meters as it continued to use the definition of 1893, making it a bit longer than the international foot. However, the difference between the two is proportionately too small for most purposes, as they only differ by 2 parts per million. At foot-length scales, the difference is a fraction of a micron, with longer measures (where the error grows to a notable degree) requiring an already excessive implied precision likely to mismatch its true accuracy. Some engineering or scientific applications may involve such tolerances, but would be expected to consistently use some more modern standard of measurement to avoid such confusion.

In the fourth panel, Cueball says that Black Hat is drawing the world 610nm closer to madness, which is about the difference between the two measures (per foot). Cueball, outraged, then tells that the National Institute of Standards and Technology (usually abbreviated with NIST) has been authorized to capture Black Hat to stop him from using the US survey foot. The joke here is that his coordinates show that he is 8,000 miles away, but since he is using the US survey foot, he is 0.016 miles away from the search team, making them unable to find him at that exact spot. (A good strike team would likely keep looking, but perhaps being strictly NIST-trained to adhere to particularly exacting standards has ironically made them vulnerable to the same inaccuracies that they are supposed to be preventing.)

Note – 0.016 miles is about 28.16 yards (84.48 feet), or 84.4798 US Survey Feet, or 25.749 metres.

Randall is playing a bit fast-and-loose here. To make this joke work implies a rather absurd situation: that both Black Hat and the searchers have set their devices to measure and report location in reference to the same location (the place where Cueball is and that is one end of the 8,000 mile measurement) and not just use GPS and lat/long like every other smartphone on the planet. The only location that can be reasonably inferred based on the comic's info is NIST headquarters in Gaithersburg, Maryland. In the unlikely event that the searchers' phones measure and report location in reference to NIST HQ, evidently Black Hat has also overridden his device's in-built GPS to report its location in reference to NIST headquarters as a way to toy with them – a curious choice that the NIST strike team doesn't find suspicious – and then traveled EXACTLY 8,000 miles away, knowing NIST would be in hot pursuit. After all, Black Hat is known for his preternatural powers of mischief.

Where might Black Hat be hiding? If he was in U.S. territory that would give them clear jurisdiction over him, but there is no U.S. territory which is exactly 8,000 miles from NIST headquarters in Gaithersburg, Maryland (regardless of which foot is used). The closest U.S. territory would probably be Cocos Island, Guam, 7923.92 miles away from Gaithersburg; the closest U.S. jurisdiction is probably the U.S. Embassy in Dhaka, Bangladesh, at 8015.14 miles. This implies that Black Hat is not on U.S. soil, which means that the NIST strike team is operating in a legal gray area, like a SEAL team catching an international terrorist.

Part of the joke is the imaginative idea that NIST employs and dispatches strike teams to apprehend persons that use incorrect measurements.

The title text references a 2013 lawsuit over the length of a "Footlong" sandwich sold by Subway fast food chain. However – in contrast to the issue at stake in that lawsuit – the difference in length between an 'international footlong' sandwich and a 'US survey footlong' sandwich is way below the precision or accuracy by which sandwiches are usually produced – making it understandable that Subway would not think it necessary to clarify which definition of 'foot' they use for their products.

Transcript

This transcript is incomplete. Please help editing it! Thanks.

[Closeup on Cueball.]

Cueball: We thought it was over. After 60 years of struggle, the US survey foot was dead, deprecated by NIST in 2023.

[Cueball is shown to be talking to Ponytail, Hairy, and Megan. He has a presentation behind him.]

Cueball: We thought architects and engineers could rest easy, free of the headaches of having two conflicting definitions of the foot that differ by 610 nanometers.

International foot: 0.304 800 000 m

US survey foot [crossed over in gray] R.I.P.: 0.304 800 609... m

[Cueball points at an image of Black Hat]

Cueball: But I bring dire news:

Cueball: Someone has started using the US survey foot again.

[Closeup on Cueball again.]

Off-panel voice: Why!?

Cueball: We don't know.

Cueball: Some people just want to drag the world 610nm closer to madness.

[Farther view of Cueball only. He clenches a fist.]

Off-panel voice: What can we do!?

Cueball: A NIST team is already in the air. We will capture the scofflaw and end this nightmare.

[Two helicopters flying, with mountains in the background.]

Caption: 8,000 miles away

[Two operatives in a forest with "NIST" helmets. One talks on a walkie-talkie.]

Operative: We've reached the coordinates of the target's device. There's no one here.

Voice from walkie-talkie: How!?

Caption: 8,000.016 miles away

[Black Hat walking elsewhere in the forest, very close by.]

Black Hat: ♫ ♪

Trivia

The number of miles in the last panel was originally 8,000.014, but was changed to 8,000.016. The latter matches the 2 ppm difference between the international foot and the US survey foot.

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Discussion

Breaking news- the comic just got changed to 8,000.016TenGolf MathHacker (talk) 17:28, 31 January 2024 (UTC)

As it should ... I did the math, and the difference between the two measurements over 8000 miles comes out to be 25.7249999 meters – which works out to be 0.0159842 of a mile.  This is, of course, why it appears that the team and Black Hat are on the shores of the same pond, with only the boulder(?) preventing the team from being able to see Black Hat. RAGBRAIvet (talk) 10:25, 1 February 2024 (UTC)

So no one has caught on to the fact that the imagery of last panel appears to be a continuation of the second-to-last panel? 172.71.155.18 (talk) 19:02, 1 February 2024 (please sign your comments with ~~~~)

Too obvious to mention explicitly. Although it does place his location at far less than 8000 miles'-worth of accumulated error. Consider it a figurative continuation. 172.69.43.170 21:23, 1 February 2024 (UTC)

He isn't 8,000 away from the NIST team. The NIST team is 8,000 miles from Cueball, Black Hat is 8,000.016 away from Cueball. The distance between Black Hat and NIST is 0.016 miles. :) i.e. same lake. NiceGuy1 (talk) 06:45, 3 February 2024 (UTC)

"8000 miles'-worth of accumulated error" isn't the full 8000(.016) miles, if that was what you were trying to clarify. Its the ±0.016 miles.

Also, current explanation says "25.749 metres, being unusually close compared to what the comic seems to depict", yet (depending upon how contiguous or uncontiguous the pond(s), rock(s) and presumably the same woodland is (it's drawn as not only inter-panel-border difference in distance, but may be not be very much more, perhaps less than a full further tween-panel would depict) I get the impression that he is actually closer than the 25m discrepancy. (As in the NIST team leader just needs to say "spread out!" and someone on the team almost instantly wanders into him by default.) 162.158.74.49 11:47, 3 February 2024 (UTC)

(cntd) There was an edit more in agreement with me (that they were close). But suggested definitely frame-border close, which I (I hope they don't mind) hedged to it not much more than (probably) frame-border close. To cover the actually unknown exact relation between the obviously related neighbouring scenes. 162.158.74.69 22:17, 3 February 2024 (UTC)

UK & Ireland Survey Foot

Until the British Ordnance Survey adopted the metre they used a foot of 0.304 800 749 1 metres. RogerWTurner (talk) 19:34, 9 February 2024 (UTC)

So US Miles, UK Miles, and "International" "Imperial" Miles are all different?172.69.194.202 12:10, 1 February 2024 (UTC)

US and UK/Commonwealth "statute miles" are 1609.344 metres (exactly, since 1959). Though based upon shared origin of 5280 (English) feet. That's probably as International as you can get. (5280*610nm is 3.2208mm of difference if you get mixed up.) But it took a while to even get to "roughly that exact".

The Roman Mile was 5000 (Roman) feet, approx 1480m, but led also to the Italian Mile of 1852m-ish by various convolutions, whilst the Chinese 'Mile' is officially 500m. Even within Britain, the Scots Mile was 1807m-ish (as seen between some historic roadside mileposts) and the Welsh version was once around 6,170m (even more historic/obsolete).

Even nautical miles are 'wrong' against what they should be, but are nonetheless standardised to their own separate international standard. (You could say "they're in a league of their own", but then leagues can be anything from 2.2km to 6.6km, at least, depending on where/when you are!) You can probably look all this up, if you really want. ;) 172.71.242.204 12:54, 1 February 2024 (UTC)

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There are (or used to be) states that specify U.S. survey measure for various things. Others that specify the international definition. Still others that just leave it undefined. Seems normal.

Although it IS a small difference, the survey grid in the U.S. and thus the property lines for a large portion of the U.S. are done with the older definition and a few reference longi- and latitudes. That could make property lines suddenly shift, so the U.S. survey foot may never fully die. I even made sure it's in my app accurately.

162.158.159.236 19:39, 31 January 2024 (UTC)

Someone should mention who NIST is (National Institute of Standards and Technology). I'm only familiar with them because of their work with information systems.

And maybe something about the absurdity of NIST having "SEAL Team"-like agents that can capture someone violating their standard. Barmar (talk) 07:20, 1 February 2024 (UTC)

The explanation doesn't mention the NIST helicopters (which have no precedent), but somehow doubts the US would send a SEAL team where they have no jurisdiction (which does). 198.41.242.118 14:00, 1 February 2024 (UTC)

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No Ingenuity tribute comic? :/ 162.158.102.64 21:07, 31 January 2024 (UTC)

Perhaps he couldn't make his original attempt fly? 172.69.43.170 21:24, 31 January 2024 (UTC)

I love XKCD, but it isn't often they make me laugh out loud. The sheer absurdity of this, and that Randall picked up on it did. 172.68.144.147 21:05, 31 January 2024 (UTC)

I measured the 2 feet that I have readily available. None of them come close to either the International or US Survey foot. And most worrying, the difference between them is significantly more than 610nm.... 172.71.99.49 11:19, 1 February 2024 (UTC)

You sure you measured correctly? The proper direction is lengthwise... 172.68.138.166 15:47, 1 February 2024 (UTC)

Please consult a healthcare professional immediately. Laser813 (talk) 20:23, 1 February 2024 (UTC)

You are non-standard. You will be eliminated. SDSpivey (talk) 17:45, 2 February 2024 (UTC)

I would think 0.016 miles would be close enough for the NIST team to be like "There he is!", :) I love how it looks like they're both on the same lake, what's with "being unusually close compared to what the comic seems to depict", to me it's DEPICTING them pretty close! NiceGuy1 (talk) 06:45, 3 February 2024 (UTC)

I know that this is a semantically annoying nit to pick, but the overall theme of the comic is about the difference between the two original measurements, not how much .016 can make in measurements. So why is decimal variance the punchline? 1245 UTC, 6 Feb 2024. 172.70.34.122 12:47, 6 February 2024 (UTC)

It's the punchline from the absurdity that two entirely separate units existed for which even over a great distance of 42.2 million feet, the variance would be only 84 feet. I had projects come to a screeching halt when the survey/international issue made stuff be wrong by less than 2'. It ends up that property owners get very protective of their property lines being exact. 172.70.126.49 (talk) 21:02, 16 February 2024 (please sign your comments with ~~~~)

Prior to 1959 the UK foot was defined by a physical object (unlike the US one which was allready defined based on the meter), so all conversation to meter where purely empirical. Hence the change was simply a measurement refinement / redefinition, akin to the multiple redefinitions of the meter and kilogram. The UK didn't have the difference at the survoyer scale issue, as UK survoyers had allready adapted metric back then.

India did have a survey foot, but this has been retired since then.--172.70.246.85 17:30, 27 March 2024 (UTC)

Interesting! What was it called? Z1mp0st0rz (talk) 15:48, 16 April 2024 (UTC)