Anyone own an Oris watch (NLC)

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Gareth
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Post by Gareth » Sat Jul 22, 2006 12:39 pm

Gonna buy this:

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Michael
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Post by Michael » Sun Jul 23, 2006 9:07 am

does the tackymeter numbers on the outside actually do anything?? Please tell me its not just for show... :shock:
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Gareth
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Post by Gareth » Sun Jul 23, 2006 10:12 am

Michael wrote:does the tackymeter numbers on the outside actually do anything?? Please tell me its not just for show... :shock:
It's used to calculate many things, but its primary purpose is to calculate a speed after noting how long it takes to travel a fixed distance (like one mile or one kilometer). The dial is a logarithmatic scale that computes the function. For example:

If you wanted to measure the average speed a car was traveling. After starting the chronometer function when the car passed the starting line, and stopping it after the car traveled exactly one mile, you noted that the chronometer hand is pointing at the 4 o'clock position, i.e. 20 seconds had elapsed. Looking beyond the 4 to the Tachymetre dial reveals the chronometer hand pointing to "180". This means the average speed of the car was 180 MPH

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robin
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Post by robin » Sun Jul 23, 2006 11:36 am

Gareth wrote: It's used to calculate many things, but its primary purpose is to calculate a speed after noting how long it takes to travel a fixed distance (like one mile or one kilometer). The dial is a logarithmatic scale that computes the function. For example:
Computing speed is a linear function, not logarithmic.

Given that the second hand points directly at the speed, and assuming the second hand marches forward at constant angular velocity (6 degrees per second, you would hope!) then the scale cannot be logarithmically formatted.

Simple arithmetic allows you to prove that the scale must be formatted as 3600/unit-interval-seconds and all it's doing is converting unit/seconds into units/hour (there being 3600 seconds in an hour) - I guess it cannot compute speeds < 60mph without cheating and using half-miles and then halving the result, etc.

BTW logarithms are usually used to avoid multiplication/division and replace them with additions and table lookups (assuming you had a table to lookup logarithms) and in the days when your telephone wasn't also a clock, calendar and calculator, having a log table on your wrist might have been quite useful ...

For example 571 x 609 = inverse-log(log(571)+log(609)).

Cheers,
Robin

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mac
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Post by mac » Sun Jul 23, 2006 11:54 am

Someone call a Moderator - that kind of stuff shouldn't be posted that early on a Sunday morning - my brain now hurts (nothing to do with the weegie night out either) :D


Mac
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Michael
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Post by Michael » Sun Jul 23, 2006 9:10 pm

Computing speed is a linear function, not logarithmic.

Given that the second hand points directly at the speed, and assuming the second hand marches forward at constant angular velocity (6 degrees per second, you would hope!) then the scale cannot be logarithmically formatted.

Simple arithmetic allows you to prove that the scale must be formatted as 3600/unit-interval-seconds and all it's doing is converting unit/seconds into units/hour (there being 3600 seconds in an hour) - I guess it cannot compute speeds < 60mph without cheating and using half-miles and then halving the result, etc.

BTW logarithms are usually used to avoid multiplication/division and replace them with additions and table lookups (assuming you had a table to lookup logarithms) and in the days when your telephone wasn't also a clock, calendar and calculator, having a log table on your wrist might have been quite useful ...

For example 571 x 609 = inverse-log(log(571)+log(609)).

Cheers,
Robin



My sentiments exactly :wink:
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Gareth
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Post by Gareth » Wed Aug 09, 2006 12:16 pm

So bought the Day Date.
Really like it in the flesh.
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GregR
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Post by GregR » Wed Aug 09, 2006 12:33 pm

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Shug
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Post by Shug » Wed Aug 09, 2006 12:46 pm

Gareth wrote:So bought the Day Date.
Really like it in the flesh.
Image
Tidy, sir. Nice :thumbsup
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deano15482
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Post by deano15482 » Wed Aug 09, 2006 2:43 pm

nice...

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