Miles per hour: inconvenent, obsolete

Ask yourself: how many people drive 40 miles, taking an hour to get there? Or 20?

Maybe on the freeway, you might go 60 miles in an hour, but it’s very likely that you’ll be going 55 part way, then 65, then 60.

Unless, of course, you have cruise control, in which case none of this matters to you.

Besides that, there’s the matter of the ridiculous unit: miles. A mile is 5280 feet, or 1720 yards, A yard is 3 feet, and a foot is 12 inches. The inch was originally defined as 1/12 of a foot (though where the “12” came from is anybody’s guess. The inch is nowadays divided into 1/2, 1/4, 1/8. 1/16, and so on). Some say the word “inch” is related to the word for thumb: in Sanskrit, for example, “angulam” = “inch’; “anguli” = “finger”.

“Mile” comes from the Latin “mille”, or “thousand”, because the average Roman soldier’s pace was 5 feet, and at that time, a mile was 5000 feet. Since then, inflation has taken effect.

In the interests of improving the world. I present a much more meaningful way of describing automobile speed: meters per second (m/S).

We’re much more likely to drive a meter at a constant speed. (I resist the temptation to do something about our awkward system of time units: seconds, minutes, hours, days, weeks, months, and years. The French tried, during the Revolution, but that failed miserably.)

During the brief time before everybody adopts this unquestionably superior system, it will be useful to have a conversion factor.

To convert miles per hour into meters per second, multiply by 0.44704. To go the other way, multiply by 2.237. If you use 0.45 and 2.2, you’ll only be off by less than a percent or so.

The test of a good system of units is whether or not we can represent common quantities in a manageable number of digits. This is why we switch from pounds to tons once the measurement of pounds goes past 4 digits.

So then, the average highway speed of 65 mi/hr is 29 m/S. Quite manageable. 20 mi/hr = 9 m/S. (Actually 8.94/S, but certainly close enough for road work.)

Since speed limit signs don’t include units (points off, there), there will naturally be a few cases of people driving 65 m/S, or 145 mi/hr, but, as this is perfectly understandable, little more than a warning and information booklet need be issued.

(There was a case, some years back, where a car driven by foreign tourists was stopped for going about 100 mi/hr on the freeway. When the Highway Patrol finally pulled them over, the driver explained that the sign clearly read “101”.)


7 responses to “Miles per hour: inconvenent, obsolete

  1. Fred Hammer

    Yes, I like m/S for auto speeds, although when you say 29 m/S it seems to me to be very fast because I visualize of all those meters flying by in only one second. On the other hand the miles are only slowly rolling by at 65 per hour. However, your case is well stated and we should all convert to metric. We use metric exclusively in the space program (except in one notorious case about 15 years ago when a contractor’s failure to use metric in one tiny, seemingly-insignificant area, caused the loss of a mission). It was a navigation-related error where the spacecraft contractor was passing information on the orientation of solar panels (in the wrong units) to the navigation team. The orientation of the solar panels has a slight, but cumutively-significant effect on the solar pressure exerted on the spacecraft and hence the interplanetary trajectory. The end result was that instead of entering mars orbit, we crashed into the planet.

  2. I used to think that everyone in America should start doing everything in metric. Since you mention time, I even had my watch always display a twenty-four-hour clock (“military” time, if you will—as opposed to the usual twelve-hour clock). I guess my rationale for both was simply that the system I preferred was objectively better, logically, in the abstract.

    But how much difference does it really make? Sure, it’s a little easier to convert from meters to kilometers (divide by a thousand) than feet to miles (divide by 5,280), and there would be fewer mix-ups and a little less confusion if everything were metric. But the fact that a probe crashed into Mars doesn’t mean we need a metric-only world; it means (I assume) that someone should have done his job more carefully.

    I also think traditional English units are part of the rich texture of our inherited culture and language. I wouldn’t want to iron them flat and replace them with a contrived order, almost any more than I would want to replace English with Esperanto.

    I stopped being so enthusiastic about the metric system (and the twenty-four-hour clock) in 2005, when I learned about Steve Thoburn. It’s tyranny for someone’s private property (in this case, a grocer’s scales) to be confiscated, and for him to be criminally prosecuted, just for doing business (with willing customers) in non-metric units, and it’s tyranny for the European Union to dictate to Great Britan that it has to dictate to its citizens like that. I didn’t want to be on the same side as the tyrants. (I’ve measure in English units and kept my watch in twelve-hour mode ever since.)

    Apparently enough Britons felt the same way that the European Union has since relented a little. It’s still a problem that the decision is up to European Union proto-dictators in the first place, and still “‘If a trader tries to conduct his business in just imperial measurements that will be illegal,'” but it’s something.

  3. lectorconstans

    Thanks for stopping by. I’ve been using 24-hour time probably forever – Army dad; I did 3 years way back when. It always seemed more logical. You don’t have to add “am” or “pm”.

    You’re right about the Mars probe – people should really pay attention.

    I remember the Thoburn case (or at least, one very like it). It’s a case of the Tyranny of the Minority – or at least, people who think they know better imposing their will on the rest of us. (We see many of the same types here in the US. They seem to be attracted to government, especially in Bureaus, where they can make hard and often silly rules without the inconvenience of asking the man in the street.)

    I’ve been calling it “Formerly Great Britain” for a few years now. I doubt they’ll get it back.

    The 2007 BBC article is a small sign of hope. I winced when they went to metric currency. There was always something fine and British about pounds, pence, farthings, quid, guineas, and “thruppence tuppence ha’penny”. I had lots of admiration for the clerks (like Bob Cratchit) who could add up columns of British amounts and come out correct.

    The overlying problem, of course, is that the EU is trying to impose its will on everybody else.

    Rather like our own Government telling us (as you describe in an earlier post) that incandescent light bulbs are Bad for You. California has already banned 100-W bulbs. As usual, the cure is worse than the disease – as in an earlier case, where they told oil companies they must put MTBE in the gasoline, and a year or two ago told us that MTBE wasn’t all that good after all, and that we’d have to get rid of it from our gas and from the ground. At our expense, of course.

    I like your blog. I do believe we’re on the same page.

  4. Thank you, you’re very kind, and likewise!

  5. I just realized that you mentioned you served in the Army. Thank you for your service!

    Re “formerly Great Britain”, I’ve just been reading Mark Steyn’s After America, which has a whole chapter on the decline of British empire, culture, and, well, pretty much everything else. Great stuff, but so depressing…

  6. I’ve seen the ads for “After America” – it’s on my list of things to read.

    Speaking of “metric snobbishness” (I was, a minute ago): There’s an article on, about cooling water to -55 deg F.

    Most of the comments scold the writer for using those icky nasty old-fashioned English units.

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