Measurements

Aughnanure · Post by **Aughnanure** » Thu Jan 05, 2006 3:36 am

We all know the importance of accurate measurement but how many of us ever think how our systems came about?

Here's two ends of a part of the story.

"It is ordained that three grains of barley, dry and round, make an inch..."

The Statute for Measuring Land. 33Edw.1, Statute 6 (AD 1305).

"The metre shall be equal to 1,650,763.73 times the vacuum wave-length of the orange line of the Krypton 86 atom, the radiation being ideally specified by the unperturbed transition between the levels identified by the spectral terms

2P10 and 5d5".

11th General Conference of Weights and Measures (1960)

That's the best that I could do on this computer with the maths symbols.

Now haven't you always wanted to know how accuraccy is achieved?

Eoin.

Brass Rat · Post by **Brass Rat** » Thu Jan 05, 2006 7:13 am

The barley one makes more sence to me.

Tom-May · Post by **Tom-May** » Thu Jan 05, 2006 1:59 pm

Eoin,

The metre has since been re-defined (in 1983) and is now the distance covered by light travelling in a hard vacuum in 1/300 000 000* of a second.

I think they may have had difficulty working out which orange-red line was the one specified

Tom

* My source states 1/299,792,458 of a second.

Aughnanure · Post by **Aughnanure** » Thu Jan 05, 2006 4:14 pm

Tut, tut ! Tom,

Rounding out to the nearest ???

Accuracy, old chap, accuracy

I'm glad to be brought up to date though. The trouble with getting so technical is that it spoils some good things. Not many people could answer correctly when asked what was the American stanard of measurement. Few knew that it was the Metre and that the US then converted to Imperial for ordinary use. Their reference metre was kept in Paris. This would have caused a theoretical problem in WW2.

Eoin.

spearedum · Post by **spearedum** » Mon Jan 09, 2006 1:11 pm

I look back at my past and I can not believe how accurate I must have been: I started out as a draftsman being extreamly precice to 1/64th. of an inch. Than I was a artillery surveyor... precession to the ntn. degree splitting a circle into 3600 mils. Statistical annalysis at the VAMC at Loma Linda, CA., and now directing and editing to 1/30 of a second!

AAAAAAAHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!

Give me the joys of MAH.

thanx Dante'

Brass Rat · Post by **Brass Rat** » Mon Jan 09, 2006 1:51 pm

Isn't there 6400 mils in a circle?

spearedum · Post by **spearedum** » Mon Jan 09, 2006 2:16 pm

everyone's a critic... so I was off a few mils!

Thanx Dante'

long live in my past Buryl

Jethro · Post by **Jethro** » Tue Jan 10, 2006 10:52 am

... and I find it almost incredible. I always wondered where those shorts came from.

OneFreeTexan · Post by **OneFreeTexan** » Thu Jan 12, 2006 4:20 pm

Oh, that kind of measurements!

Wasn't what I was hoping for.