[AT] Supposedly why our old tractors are not metric and a fairly simple tutorial
Thomas Martin
tmartin at xtra.co.nz
Tue Feb 25 12:10:27 PST 2020
Well the French had been measuring objects with better accuracy than most, since 1631 when Vernier
invented his secondary scale...
That the French didn't make their Standards out of copper could be a result of the of the accuracy of their measurement.
Tom
> On 26 February 2020 at 07:11 Stephen Offiler <soffiler at gmail.com> wrote:
>
> 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 mailto: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> mailto: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 mailto:robinson46176 at gmail.com
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
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