# Tachometer on a wristwatch? Huh?
**URL:** https://boards.straightdope.com/t/tachometer-on-a-wristwatch-huh/229118
**Category:** In My Humble Opinion
**Created:** [February 13, 2004, 10:49pm UTC](https://boards.straightdope.com/t/tachometer-on-a-wristwatch-huh/229118 "2004-02-13T22:49:02Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Algernon](https://boards.straightdope.com/u/Algernon)
#### Post date: [February 13, 2004, 10:49pm UTC](https://boards.straightdope.com/t/tachometer-on-a-wristwatch-huh/229118/1 "2004-02-13T22:49:02Z")
I know most of you have probably seen these ads in magazines for this [Steinhausen 1923 replica watch](http://www.steinhausendirect.com/). I actually kind of like the looks of this watch, but what the heck is with the numbers around the outside of the dial, labeled “Tachometer”? The numbers go around the dial counter clockwise, increasing in what looks like a logarithmic manner.
Two questions:
a) of what possible use are these numbers? (is it just supposed to look cool?)
b) and why would they be on a replica of a 1923 watch?
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### Author:  [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)
#### Post date: [February 13, 2004, 11:07pm UTC](https://boards.straightdope.com/t/tachometer-on-a-wristwatch-huh/229118/2 "2004-02-13T23:07:08Z")
> [@Algernon](#):
>
> Two questions:
>
> a) of what possible use are these numbers? (is it just supposed to look cool?)
> b) and why would they be on a replica of a 1923 watch?
My guess is the original function was to tell the wearer when the watch needed winding.
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### Author:  [@LVgeogeek](https://boards.straightdope.com/u/LVgeogeek)
#### Post date: [February 13, 2004, 11:25pm UTC](https://boards.straightdope.com/t/tachometer-on-a-wristwatch-huh/229118/3 "2004-02-13T23:25:45Z")
A watch shouldn’t have a “tachometer” that would be stupid and useless,
unless it was somehow wireless and perhaps used for cycling, this is
obviously not the case…
watches do, however, have “tachymeters”, my husbands Omega Speedmaster has one, the tachymeter is used to measure high rates of motion per hour, it is a dimensionless measure that is applied to a count or distance. the calibration is in a
reducing number scale around the second hand, usually begins with a
unit around 500 somewhere near the 5 second mark, the second hand is started
and then stopped after one unit has passed, if it takes a full minute,
then the rate is 60 units per hour.
I have seen the watch advertised, I did not notice that the fools had
called it a tachometer, it can even be seen on the watch!
a tachometer and a tachymeter are actually similar, but a tachometer
gives an instantaneous measurement the same as on a speedometer this is done
through gear reductions and spring tension. a tachymeter gives an
actual sampled and calculated measure it relates the count to the sample time.
That’s probably a lot more than you wanted to know
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### Author:  [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)
#### Post date: [February 23, 2004, 4:17pm UTC](https://boards.straightdope.com/t/tachometer-on-a-wristwatch-huh/229118/4 "2004-02-23T16:17:46Z")
I e-mailed the company on the 14th to ask about the misspelling, and received a reply today:
> [@](#):
>
> The unit on the watch does not work. It was only put on the watch to make it look exactly as the orginal watch.
I e-mailed them back to ask if “tachymeter” was misspelled on the original watch. (I also pointed out that all you need for a tachymeter to work is a stopwatch second hand.)
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### Author:  [@cybersnark](https://boards.straightdope.com/u/cybersnark)
#### Post date: [February 24, 2004, 3:14am UTC](https://boards.straightdope.com/t/tachometer-on-a-wristwatch-huh/229118/5 "2004-02-24T03:14:02Z")
Uhh - the scale on the watch DOES work, if you know how to use it. It is used when traveling a measured mile distance, and is measured by the sweep second hand. Thus, if you travel the full mile from start to fininsh in the same time the second hand sweeps a full 60 seconds, you’re traveling 60 mph, and that is what the little number is on the outside scale on the watch. Likewise, if you travel the mile in 15 seconds, you’re going 4 times as fast or 240 mph, which is what the scale reads. However, it IS a tacymeter, not a tachometer - I can’t believe they screwedup the spelling!
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### Author:  [@Algernon](https://boards.straightdope.com/u/Algernon)
#### Post date: [February 24, 2004, 2:25pm UTC](https://boards.straightdope.com/t/tachometer-on-a-wristwatch-huh/229118/6 "2004-02-24T14:25:00Z")
I’m embarrassed to confess that until reading **LVgeogeek’s** post I didn’t know that there was such a thing as a tachymeter. Though using the watch for that purpose seems to have very limited practical use, it makes sense. I suppose you could measure tenths of a mile and do the conversion.
**cybersnark** and **Johnny L.A.** , I did a bunch of web searches and found that often the ad copy will say “tachometer” but the watch itself is labeled “tachymeter”. [Here is an example of a Tag Heuer.](http://www.ashford.com/product/index.asp?pf_id=18928&sourceid=qDQQQDtcyCc9AarTp0TY0027972519&GEN5=ASHAFF02ASHAFSRF&dept_id=120&md_id=2) [This site claims the two words are synomyns.](http://www.time4watches.com/Watch%20Terms%20by%20Letter/Letter%20T.htm)
By the way **Johnny** , I find the email response from Steinhausen to be hilarious.