- I know, I was only joking. I would probably have to

relearn it in a few years also.

--- Mike Diamond <mdia1@...> wrote:

> I was merely describing a shape, using the closest

__________________________________

> geometric form.

> But I'm sure you're aware of that. My geometry is

> probably as rusty

> as yours. But with my daughter just having entered

> Junior High, I'll

> have the pleasure of relearning it all over again.

>

> Geometry is of inestimable value in, for example,

> calculating the

> expected weight of any wrong stock error. It's also

> useful in

> calculating expected densities of alloys for which

> no SG value has

> been published.

>

> --- In errorcoininformationexchange@yahoogroups.com,

> Al

> <bull102797@y...> wrote:

> >

> > So, if, in a triangle, angles a, b, g lie opposite

> the

> > sides of length a, b, c, thensign(a + b - g) =

> sign(a2

> > + b2 - c2)

> >

> > --- Mike Diamond <mdia1@a...> wrote:

> >

> > > To be more precise, the shape is that of an

> > > isosceles trapezoid.

> > > This link with provide a precise definition.

> > >

> > >

> http://mathworld.wolfram.com/IsoscelesTrapezoid.html

>

>

>

>

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http://farechase.yahoo.com - --- In errorcoininformationexchange@yahoogroups.com, "Mike Diamond"

<mdia1@a...> wrote:

> Geometry is...also useful in

I don't know why I said this. Simple algebra (calculating a weighted

> calculating expected densities of alloys for which no SG value has

> been published.

average) is what I use to arrive at an expected specific gravity. I

inevitably come up with the same values as those that have been

published. All you need to know is the SG of each metallic element

(easily found on the internet), and the percentage of each element used

in the coin.

Since published tables occasionally have mistakes, you can easily

double-check the SG values yourself. - One note when doing sp grav tests, use room temp. distilled water

--- In errorcoininformationexchange@yahoogroups.com, "Mike Diamond"

<mdia1@a...> wrote:>

has

> --- In errorcoininformationexchange@yahoogroups.com, "Mike Diamond"

> <mdia1@a...> wrote:

>

> > Geometry is...also useful in

> > calculating expected densities of alloys for which no SG value

> > been published.

weighted

>

> I don't know why I said this. Simple algebra (calculating a

> average) is what I use to arrive at an expected specific gravity.

I

> inevitably come up with the same values as those that have been

used

> published. All you need to know is the SG of each metallic element

> (easily found on the internet), and the percentage of each element

> in the coin.

>

> Since published tables occasionally have mistakes, you can easily

> double-check the SG values yourself.

> - In a message dated 10/29/05 10:34:38 A.M. Central Daylight Time, RichErrors@... writes:
One note when doing sp grav tests, use room temp. distilled water

Yes. Other advice includes:1. using a vibration-free table2. making sure the surface the balance is resting on is perfectly level3. tapping the submerged coin and its holder to liberate any micro-bubbles4. use a balance accurate to at least the nearest .01 grams, and preferably .001g.5. do multiple tests to reduce random fluctuations in SG value6. test a sample of normal coins to establish a range of variationSG is simple in concept, but tricky to execute well. - These tips are in order for SG measurement. See below for

other desirable tips.

--- mdia1@... wrote:

>

Also take into consideration wind gusts. Balance should be

> In a message dated 10/29/05 10:34:38 A.M. Central

> Daylight Time,

> RichErrors@... writes:

>

> One note when doing sp grav tests, use room temp.

> distilled water

>

>

> Yes. Other advice includes:

>

> 1. using a vibration-free table

protected from ANY movement whatsoever.

> 2. making sure the surface the balance is resting on is

And...letting the balance stand in the wet measurement for

> perfectly level

> 3. tapping the submerged coin and its holder to liberate

> any micro-bubbles.

about a minute or so would allow bubbles to break up some

more.

> 4. use a balance accurate to at least the nearest .01

The more precise a balance is the more reproducibility in

> grams, and preferably .001g.

the final SG calculation.

> 5. do multiple tests to reduce random fluctuations in SG

The use of a "standard" coin whose SG is known to a much

> value

> 6. test a sample of normal coins to establish a range of

> variation.

higher degree is a great advantage for calibration

purposes. Since you know this SG to a very precise level,

the running of this coin's SG in your system will easily

tell how good is it.

The use of calibration weights for your balance might be a

good idea. If your balance is not retrieving weight

consistently throughout the range, your results will vary

widely.

> SG is simple in concept, but tricky to execute well.

Yep. It sure is.

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