Wednesday, August 26, 2020

Why is a mile 5,280 feet? (Why is a nautical mile different??) +"naked Greeks are involved, and Jesus, and Vikings"

From the blog of Peter S Magnusson:
The original Roman mile was 1000 paces (milia passuum), or 5000 feet. The modern mile was defined as 5280 feet under Queen Elizabeth at the end of the 16th century in order to reconcile multiple discordant measurement systems already in wide use. In particular, it was convenient to make it an even multiple of the sides of an acre, which since early medieval times was a rectangle 660 feet long and 66 feet wide. 660 divides neatly into 5280, eight ways, allowing a square mile (640 acres or a “section”) to be conveniently quartered three times over: into quarter sections (160 acres), sixteenth sections (40 acres), and finally the 10 acre squares (660 by 660 feet) that remain at the base of all US land surveys to this day.

Background: Many years ago, I became curious as to why, exactly, there are 5280 feet in a mile. The explanations I found online at the time weren’t very convincing. At the time I tried to make some fixes to parts of the puzzle in Wikipedia, but they frequently rejected as OR (original research). Eventually I wrote this article, since revised and updated several times. Since then, my “version” of things will occasionally drift to the #1 spot on Google or Bing, or both, when answering the specific question “why are there 5280 feet in a mile”. More often some SEO-optimized version will slip ahead, though it seems this article is holding steady in the top 3 or 4 at least. So hopefully pretty much everybody who cares about the details will find this. If you have any comments or questions (or corrections), please add to the comment section, I do (eventually) read all comments.

I have yet to find an answer to the question that’s as thorough and complete as this one is. But I must caution that this article isn’t really up to academic standards and contains a non-trivial amount of speculation. Caveat Emptor, what follows is my theory of how the mile ended up with 5280 feet.

The conventional wisdom on this topic goes something like this: the mile was originally 5000 feet. It was changed to 5280 feet in Elizabethan times around the year 1600 (some point to 1592 and some to 1593) to accommodate the furlong, which was 660 feet. It was easier to fix the mile rather than the furlong for various reasons, hence, eight furlongs and 5280 feet in a mile.

That’s the standard story. It’ll be fleshed out with bells and whistles, including odd theories about horses etc, but that’s about it.

The problem with these versions is that they don’t explain why this collision between furlong and mile occurred around 1600, and not centuries before. It implies, therefore, that people suddenly woke up and realized, hey, wait a second, if there’s 660 feet in a furlong … and eight furlongs in a mile … but 5000 feet in a mile …. wait a second !?!

It somewhat implies that four-digit multiplication was invented ca 1600. Like a lot of rear-view-mirror takes on history, the “explanation” boils down to: “before time X people were stupid about topic Y, and at time Z they wizened up.”

Failing to find a good write-up of the origins, I’ve pieced together my own theory over the years. And it’s a fun one because the answer (or rather, hypothesis) is simply this: the number 5280 arises out of a collision between organized religion, the military, and taxation. Three powerful historical forces, to be sure, so the fourth pillar to modern society (rationality) obviously has to be the one to compromise!

But wait, there’s more: naked Greeks are involved, and Jesus, and Vikings. In that order....

HT MetaFilter: