I noticed on my new watch that I just bought that there is a scale going round the edge and is labelled a TACHYMETER. Does anyone know what a tachymeter is?

Very interesting question. I've been wondering that for a long time too.

Here's what I found on http://www.omega.ch/omega/he_faq?print=true&print=true#q14

"A tachymeter is an instrument for measuring speed. It is a chronograph with a graduated dial on which speed can be read off in kilometres per hour based on 1000 metres distance.

How to read an observation on the tachymeter: Only the central chronograph seconds-hand is used. For observations of a longer duration, the indications of the timers (minutes and hours) count.

Example for calculating the speed of a car:The chronograph indicates that the distance of one kilometre has been covered in 30 seconds. The corresponding point on the tachymeter scale indicates 120. The speed is therefore 120 km per hour."

By the by, SteveH, I looked a bit further and apparently there are imperial tachymeters too.

they'll be the UK ones.

My other half does a lot of jogging and she has a joggers watch.

she had to put her height in and weight in all in imperial.

She's getting ready to run a half marathon and goes out for a run then goes out in the car to see how many miles she's covered (ie working up)
Maybe she could do with a "tachymeter"?

"they'll be the UK ones."

Oh yeah?

err, yes.

We use miles in the uk (and mph). Ask anyone.
Actually - go for a drive.

Tachymeter, hmmm.

Sounds like something for measuring how much longer it will take for that paint to dry.

OR perhaps the quality of argument on this forum :-)

Hello! Planet Earth calling!

Has everyone got their brains turned off, or what ?

A wrist watch tachymeter is NEITHER metric or imperial because the watch can't measure the distance travelled. You have to do that yourself and as a result you can specify your own units.

Using Conrad's example if you travel one "unit" in thirty seconds the watch is telling you that your speed is 120 "units" per hour.

So, measure 1km you get 120km/h.

Measure 1 mile you get 120mph.

Measure 1 elephant you get 120 elephants per hour.

Everybody happy now ? Good.

Nicely put - thanks.

P.S. I walked 8 baboons today, at the "mini in the park" event