The Magical Shrinking Kilogram!

[Patrick]

When is a kilogram not a kilogram? When it starts to weigh less. It came into existence more than two centuries ago and has become the standard unit of weight around the world, from the shopping malls of Europe to the souks of the Middle East, but scientists believe that the reign of the kilo as we know it is about to come to an end.

A group of experts meeting in London today want to redefine the kilogram so that it is no longer based on the mass of a solid cylinder of platinum-iridium alloy that sits beneath three layers of protective glass sealed in a locked vault in Sèvres, France.

This metal block, known as the International Prototype Kilogram, has been used since it was first registered with the International Bureau of Weights and Measures (BIPM) in 1889 as the definitive unit of mass against which all other kilograms are measured.

In the past 122 years, it has been brought out of storage just three times to calibrate the national prototype kilograms used by countries around the world. However, scientists now believe it is time to redefine the kilogram because there is evidence that the precise mass of the international prototype in Sèvres is not as constant as it should be.

"We think it is losing weight, and we don't know why," says the BIPM's Michael Stock, who is due to attend the meeting at the Royal Society in London that will look again at the kilogram. "From the three times we have had it out to make calibrations, we have had indications that it is not perfectly stable. It seems to have lost about 50 micrograms and there is no real explanation."

[everso]

What's a kilogram?

eversooldfashioned

[everso]

And by the way, what happened to the florin?

[Weyland]

Jan 24, 2011 17:47:58 GMT everso said:

What's a kilogram?

[Patrick]

I haven't forgiven them for giving up the Groat!

[Weyland]

Jan 24, 2011 17:48:23 GMT everso said:

And by the way, what happened to the florin?

Decimalised away on 1971.02.15, just six months before I first got married. The first thing I ever bought with new pence was The Guardian.

The florin survived until €-Day 2002.01.01 in the Netherlands. The old name for the Guilder was florijn. Hence the Guilder symbol, ƒ. The first thing I ever bought with the € was The Radio Times. They didn't sell The Guardian in that shop.

[everso]

Jan 24, 2011 18:17:49 GMT Weyland said:

Jan 24, 2011 17:48:23 GMT everso said:

And by the way, what happened to the florin?

Decimalised away on 1971.02.15, just six months before I first got married. The first thing I ever bought with new pence was The Guardian.The florin survived until €-Day 2002.01.01 in the Netherlands. The old name for the Guilder was florijn. Hence the Guilder symbol, ƒ. The first thing I ever bought with the € was The Radio Times. They didn't sell The Guardian in that shop.

Those crazy days of our youth. ;D

[Weyland]

Jan 24, 2011 18:29:36 GMT everso said:

Those crazy days of our youth. ;D

How true. But I got over it, and read The Observer nowadays.

[aubrey]

I had to check then what a florin was - 10p. I mean, I had assumed it was that. I still think of 10ps as florins, sometimes.

That Kilo thing: I get confused by the extra decimal place on the scales I use at the hospital now. I think I read from right to left. "74.75" where it used to be "74.7;" I go back to write it down and find myself wanting to write "47.5."

[everso]

I shall never get used to metric weights and measures. I've only just adjusted to decimalisation - and if you mention ten shillings it STILL seems like a lot of money.

[Weyland]

Jan 25, 2011 16:56:59 GMT everso said:

I shall never get used to metric weights and measures. I've only just adjusted to decimalisation - and if you mention ten shillings it STILL seems like a lot of money.

Calm down, dear!