Hacker News new | past | comments | ask | show | jobs | submit login
[dupe] Why are there 5280 feet in a mile? (2009) (petersmagnusson.org)
23 points by wellokthen 37 days ago | hide | past | favorite | 21 comments




Ouch, that is a hell of a dupe to miss. Thanks!


I grew up in a metric using country, I didn't learn imperial until I had to for a job. I came to appreciate the way being broken into 16ths, 8ths, 4trs, and halves really worked well for hands on practical things.

Unfortunately, I had to work in decimal inches a lot and had to convert back and forth between metric and that's where the arbitrariness of the imperial system began to make my brain hurt.

1.181 inches will forever be burned in my mind as the near almost but still not quite exact equivalent of 3cm...and the day the customer took out a measuring tape and lost their mind because we gave them something 3cm, what it was sold as and agreed upon by them as, and not the 1.25 inches they expected. The material we produced with came in 3cm not an inch and a quarter. For some reason, the customer believed they were getting inch and a quarter material despite it never being listed anywhere in any plans or marketing they received from us and despite the material not being manufactured in any thicknesses other than 2cm or 3cm. They literally threw the measuring tape at my coworker over those .069 inches...


Sucks that your customer didn’t pay attention to the details, but I can understand losing your mind over a 0.069 inch mistake. That’s greater than 1/16 inch. It’s huge.

In fact, I think that would be outside of any allowable tolerance in any industry I can think of, except for maybe rough-in framing in home construction.

Curious, what was the medium and how expensive was this mistake?


The medium is stone, the mistake was not a mistake, the difference was not noticable.


Yes, the successor to the 5000-foot Roman mile should have been 5040, but 5280 isn't bad for something that arose organically out of various unit systems' needs.


It's not great. We have a base 10 number system so everything should be in powers of 10. Not too familiar with my 528 multiplication tables.


2, 3, 4, 5, 6, 8, 10, 11, 12, 15, 16, 20, 22, 24, 30, 32, 33, 40, 44, 48, 55, 60, 66, 80, 88, 96, 110, 120, 132, 160, 165, 176, 220, 240, 264, 330, 352, 440, 480, 528, 660, 880, 1056, 1320, 1760, 2640.

5040 is of course well-known as one of the most factorable numbers of all time:

2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 28, 30, 35, 36, 40, 42, 45, 48, 56, 60, 63, 70, 72, 80, 84, 90, 105, 112, 120, 126, 140, 144, 168, 180, 210, 240, 252, 280, 315, 336, 360, 420, 504, 560, 630, 720, 840, 1008, 1260, 1680, 2520.

But 5280 isn't bad. And it gets 11, though it misses 7 and 9. 5040 only misses 11 out of 1-12.

5000 is pathetic. 2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 125, 200, 250, 500, 625, 1000, 1250, 2500.


> We have a base 10 number system

You hit the nail on the head. Bases 12 amd 60 are much handier as they have more factors.


I agree, but the odds of switching the default base to either is extremely low.


Metric system foolishly went the wrong way. Didn manage to displace the calendar, degrees in a circle, minutes and seconds, etc, despite attempting to.


How often are you converting miles to feet?


Giving road directions, especially if you are sitting in the passenger seat navigating for someone, is an example that comes up in my life fairly frequently. It gets awkward to talk about things that are between 0 to 1/2 mile so I find myself trying to do the mental math to convert to feet for someone else. These days I usually give verbal directions in meters. Most people in the United States seem to have some conceptualization of what a meter is so it usually works quite well as it’s also easier for me to estimate meters instead of feet.


>Most people in the United States seem to have some conceptualization of what a meter is so it usually works quite well as it’s also easier for me to estimate meters instead of feet.

I think most people in the US just convert the meter to the three-foot yard measure. I doubt people would notice if you did the same thing in order to give estimates in feet. I work in metric weights but speak to people using US Imperial weights, so I regularly say something is "about 4 ounces," and the same idea of something being "about 1000 feet" would likely be fine since you're already estimating.


Given that road directions aren't even remotely precise, it's fine to just consider a mile to be 5000 feet, and if you want to say "a quarter mile" you can just say 1250 feet. Or even 1500 feet if you want something more round. Most people will not meaningfully feel the difference between "turn right after 1250 feet" and "turn right after 1500 feet" when moving at car speeds.


When I'm cycling I'm comparing metres to kilometres all the time; in imperial you'd presumably have to do the same with feet to miles (or maybe yards, but they seem to be a more obscure measurement - e.g. people talk about speed in feet per second but not in yards per second).


In imperial/US (which are not identical) you simply think of it differently, using a quarter mile, half mile etc. Using rational fractions (1/2, 1/3, 1/4 ... 11/16 etc) are very simple and natural in that system. Having lived in countries that use on or the other, or have transitioned (and having been born before currency decimalization) I appreciate the strengths and weaknesses of both systems, and use each in its “natural” mode, just as I don’t speak a second language using the grammar of the first.

Metric is not “automatic” either. One year in university I took three classes that happened to be in the same classroom. One was in cgs, one was in MKs and one in ASME units (US customary units plus mils). Three different subject domains. It didn’t feel odd or complicated.


Never since I'm not American, but if I were I'd use a calculator. I think this is primarily bad for kids who have to do miles to feet conversion in math problems. It could even be lowering math scores, who knows.


My local swimming pool is two hundred feet long


Never. But meters to kilometres all the time.


Are there any liquid measures (or volume units in general) odder than acre-feet, whose unit parallelepiped is furlong x chain x foot?




Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact

Search: