S.I. or British M.U.?

[Mike Halmarack]

There's more to it than ease of measurement. What would you rather have fat middle aged greengrocers do? Weigh bananas by the pound or throw molotov cocktail parties?

[Mary Fisher]

:-)

I suspect that might cause some head scratching ...

Mary

[Mike Halmarack]

In some cases, though most people use disposable gas lighters these days. :-)

[Rob Morley]

500 ml containers.

local supplier is.

Hereabouts you get pints in Asda Sainsbury Tesco but litres in Co-op.

[Rob Morley]

It's 4.5 litres to the gallon, not 5.5. ISTR that metrication happened around the same time as an "oil crisis".

[Rob Morley]

Does the navy still use knots and fathoms?

[Christian McArdle]

Yes, round here (Reading), the supermarkets have pints and the smaller shops have litres.

Christian.

[Christian McArdle]

What age are you? I know few people under 40 who use mainly imperial for other than specific things.

Christian.

[Guy King]

The message from "Christian McArdle" contains these words:

You know why that is, don't you? The metric size in each case is smaller than the similar imperial size so they can disguise the higher prices more effectively.

[Christian McArdle]

Actually, the local shop sells milk at considerably lower prices than the supermarkets. 3 litres costs 1.09. Sainsburys sell 4 pints (2.27L) for 1.00. Extrapolating the 4 pints up to 3 litres, it would cost 1.32.

Christian.

[Mary Fisher]

In Waitrose you get both measures according to the supplier.

Mary

[Mary Fisher]

Doesn't take away the itch ...

Mary

[Mary Fisher]

Which navy?

[Christian McArdle]

No idea. However, knots are used in aviation.

They are also not an arbitrary unit, like the statute mile. Indeed, the nautical mile and metre were both originally based on approximations of the same measurement.

A metre was originally supposed to be one 10,000,000th of the surface distance from pole to equator. A nautical mile is one minute of arc of the planet's diameter, i.e. (360*60)th of the earth's diameter.

Equating these,

(360*60)nm = 4x(10,000,000)m.

i.e. 21,600nm = 40,000,000m.

or 1nm = 1852m.

This was the original derivation. The metre is now defined by an atomic based standard and the nautical mile (like imperial distances these days) is based on the metre. However, based on their original derivation, the two units basically share the same original source.

Christian.

[Mary Fisher]

Yes, really memorable and with a visual meaning.

Mary

[Christian McArdle]

In terms of immediate human visualisation, there's not much to choose between the length travelled by light in a vacuum during 1/299,792,458 of a second and a 40,000,000th of the earth's diameter.

Then, the inch is no better. It is now defined as the length travelled by light in a vacuum during 1/11,802,852,677th of a second...

Christian.

[Mike Halmarack]

I hope this particular itch isn't associated in some way with your current interest in the navy. Unvetted sailors are best avoided,. particularly those with monikers like "Ophelia".

[Mary Fisher]

Much easier to look at the top joint of one's thumb. and I know what you're going to say, but it's good enough for most of us - was for a very long time.

Mary

[Mary Fisher]

Indeed.

>

[Christian McArdle]

Yeah, but you'll find similar measurements that approximate metric measurements too. My finger is 1cm wide and much easier to line up multiples than a thumb at 90 degrees. Besides, my thumb is over an inch.

Christian.