[AT] Supposedly why our old tractors are not metric and a fairly simple tutorial

[Stephen Offiler]

Same thought went thru my mind when I read about the copper length
standard.  But wait a minute.  It might not have been such a bad choice.

First, even the most rudimentary understanding of the concept of thermal
expansion (which I assume they might have had back then) would suggest that
the standard is only truly correct at a single temperature.  Variaton from
that temperature would result in either expansion or contraction.  True for
all metals, and copper (including its alloys) isn't ridiculous in this
regard.  It's about 10 x 10^-6 /degF.   For comparison, steel and iron have
a value around 6.  Yes, almost twice as good, but then there's that pesky
rust factor.  I'm not sure what else was common then... below steel,
considering anti-corrosion, we have antimony, platinum, and titanium at
around 5, molybdenum at around 3, tungsten at around 2.5.  Again, not sure
whether any of these were an option back then.

Let's say they could only reliably get within about 10 degrees F of the
temperature at which the standard was defined, probably room temperature.
You'd get yourself near a fireplace in the dead of winter, and you'd avoid
this kind of work altogether at the height of summer.  OK.  That 10 degree
variation would change the length of the standard by a factor of 1 x
10^-4.  (That is, 10 x 10^-6 /degF times 10 degrees F is 100 ^ 10^-6, which
is the same as 1 x 10^-4).  Meaning:  10 degreesF warmer, a 1-meter
standard would be 1.0001 meters long, and likewise if 10 degreesF cooler,
it would be 0.9999 meters.  I will bet that they did not have measuring
tools precise enough to see this change.

SO


On Tue, Feb 25, 2020 at 12:38 PM Cecil Bearden <crbearden at copper.net> wrote:

> Tom:
>
> That copper bar was suspect to me also, for the simple fact that brass, a
> compound of copper will expand & contract with heat and cold.  One of our
> old sayings it "Cold enough to freeze the balls off a brass monkey".  A
> monkey was the holder sort of shaped like a hand for cannonball on a
> ship.   They were made of brass.  At exceptionally cold temps, the metal
> would contract and the balls would fall off the monkey..   So came the
> saying to describe the weather....    Kinda like colder than a well diggers
> butt in Utah....   One of my dad's old sayings...
> Cecil
> On 2/24/2020 5:50 PM, Thomas Martin wrote:
>
> A bit of creative writing... Certainly chronologically challenged, with
> Dombey captured allegdly
>
> in possession of a Standard meter, 4 years before the length was
> established. :-)
> FYI From more  credible sources:
>
> The metric system *was* first proposed in 1791.
> It *was adopted* by the *French* revolutionary assembly in 1795,
> and the first metric standards ( a standard *meter* bar and kilogram bar)
> *were adopted in 1799*. *The length of the meter bar was only established
> in late 1798*
>
> The Standards weren't made of copper but Platinum. Copper wouldn't be
> stable enough
>
> temperature wise.
> There *was* considerable resistence to the system at first, and its use
> *was* not made compulsory
> in *France* until 1837.
>
> Tom
>
> On 25 February 2020 at 03:08 Indiana Robinson <robinson46176 at gmail.com>
> <robinson46176 at gmail.com> wrote:
>
> I'm not sure how accurate this story is but it matches what I had read for
> years.
> https://www.thevintagenews.com/2018/04/12/metric-system-usa/
>
> If they had listened to Jefferson we would  not be messing with a double
> system, metrics would just be what we use...  The 10 based system can be
> done in  your head (could have saved all those years learning those damned
> fractions)  :-)  and every tool box wouldn't have a fraction to decimal
> conversion chart tucked in somewhere that you can't ever find when you need
> it. Also we would not have to worry about some dead kings thumb size
> getting lost or a bad few years for the barley crop or a lot of other stuff
> they tried to set as standards long ago.
>
> This site looks fairly well done and I liked the little section on the
> metric size of a few common objects.
>
> https://www.wikihow.com/Measure-Centimeters?fbclid=IwAR1z77b9GTGRpTD7TM1cH51LA1CKzsTyPJ-n87HsRDmbJv7b5ME7QyCVpbs
>
> If you have forgotten how to use your Abacus there is a section on that
> too.  :-)
>
>
> .
>
> --
> --
>
> Francis Robinson
> aka "farmer"
> Central Indiana USA
> robinson46176 at gmail.com
>
>
>
>
>
>
>
>
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