Comment by zeveb | Hacker News Reader

Comment by zeveb | Hacker News Reader

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> vastly easier to use for a large number of tasks that a large number of people need to do frequently (specifically, arithmetic on measurements).

At the expense of being vastly more difficult for a large number of tasks that a large number of people need to do frequently (specifically, manipulation of physical quantities).

What do I mean? It's very, very easy to take a pound of some substance and reduce down to ounces with a balance: halve, halve, halve & halve again. It's very, very easy to take a gallon of some liquid and reduce it to gills: halve to get 2 pottles, halve each again to get 4 quarts, halve each again to get 8 pints; halve each again to get 16 cups; halve each again to get 32 gills. It's easy to cut a yard into feet (thirds) or a foot into inches (thirds, halves, halves).

But it's very difficult to manipulate physical quantities in the French Revolutionary system: if you have a kilogram of some substance, turning it into decigrams is … a right royal pain, because dividing a weight into tenths with a balance is a chore; you need a set of pre-measured weights to do it. Ditto with a litre; ditto with a metre.

If the French had really wanted to make a difference, they'd have chosen to introduce a different base for arithmetic …

(I certainly agree that it's nice that the whole world has settled on one standard; I just wish that it were a better standard. Much the same as with computing & x86/C/Unix.)

I'm a bit baffled by how you think turning kilograms into decigrams is 'a right royal pain', multiplying by 10000 seems pretty simple to me.

> I'm a bit baffled by how you think turning kilograms into decigrams is 'a right royal pain', multiplying by 10000 seems pretty simple to me.

That's performing arithmetic (and you're of course correct: in base 10, multiplying by 10,000 is really easy — just slide the decimal point right), not manipulating a physical quantity. Take a gram of sand, and try to cut it into 10 decigram-weight quantities using a balance without a pre-existing decigram weight. You're going to have a hell of a time: there's no good way to divide a physical quantity of stuff (whether a volume, a length or a weight) into tenths. It's much easier to divide things into halves and (less easy) thirds.

Thanks for commenting, though. I wonder if others misread similarly (and I've added one word to clarify). I can't imagine anyone seriously believes that it's easier to divide quantities of physical substances into fives or tens than into halves.

(as an aside, the HN rate limiter has been insane this week: I posted one article and three comments, and I've not been permitted to post for over an hour now)

Dividing a gallon into tenths is easy. Pour it into a measuring cup until it's at 1/10th of a gallon. With sand by weight, pour it onto a balance until you get your desired weight. Easy peasey.

I'm not sure about physicality being the problem here, the ISO 216 standard, based on metric units (square meter), is used for dividing and multiplying the areas of physical things (paper) and seems to be doing rather well, each size being half of the previous one, I would say that's quite intuitive.

Granted, if we look at the tiny details, the exact measurements of each size are not what one would call intuitive, round numbers, but it's much easier and reliable to use than the US, non-decimal based standard.

I think it's mostly an economic problem, for the majority of people it's too much trouble for very little real gain. For engineering, on the other hand, it's almost mandatory.

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