watch question

[streetfighterjeff]

guys, want to pick all you clever folks brains. you know when you get a watch with a "tachymeter" round the outside bezel? how the hell do you work it all out? had a sports watch for a couple of years now and have never been able to work it out and the handbook doesn't say. anyone got any ideas?
jeff

[oz]

try the first link on here. http://en.wikipedia.org/wiki/Tachymeter_(watch)

oz