Message for Simon of Harman/ Ilford

The meter was redefined in 1983. What it was before that was perfectly clear, and standardized.

And that's the thing this off-topic spin-off is about: the assertion that measurements make sense because they "correspond to a human-sized useful measurement" is seriously flawed.
The meter was defined by drawing two lines on a bar of metal, and saying that the distance between those marks would be the meter. No unclear my-foot-is-bigger-than-yours "human sized usefull measurements".

It was so clear, simple and unproblematic that there never were local variations of the meter, or all the mix-ups you get without a clearly defined unit.
On the other hand, i don't think the act of 18-something-or-other did more than get the Scottish units of the same and different names in line with the English units. Or did it?

Anyway, as long as you clearly define a unit, it is clearly defined. Since the late 1950s, there shouldn't be a problem converting UK inches (etc.) to meters. It's clear, and easy.

The only remaining thing is the complexity of the system of units.
For that i can only refer to (there was a url link here which no longer exists).



Back on topic:
I think that providing beginners with help, supplying 'old hands' with usefull in depth tips, will do lots to build a solid base of loyal customers.

And it's not as if it all has to be created from scratch: the process hasn't changed much over the years. If only the info Ilford provided many years ago was made available again, the biggest step will have been.
Fine tuning and updating to the present products should not be much work.
Publishing the lot is the easiest part of it all (though some people say they prefer hard copy, and don't want to print their own): internet and PDFs.

Q.G. said:

The meter was redefined in 1983. What it was before that was perfectly clear, and standardized.

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The inch was redefined in 1959. What it was before that was perfectly clear, and standardised.

the assertion that measurements make sense because they "correspond to a human-sized useful measurement" is seriously flawed.

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I cannot see where it has been shown, as opposed to asserted, that the correspondence of measures to 'human useful-sized measures' is "flawed". Our counting system is based on ten for a reason. Horse height is measured in hands for a reason. The mile is a human-sized measure for a reason, based on the old Roman army quick-march 'passus' or 'long pace' of five foot per step, 'mille passum', or 1,000 x 5 foot, the 5,000 foot length later converted to 5,280 to line up with the later English definition of a yard. The French, those latter day champions of metric measures, hitherto used 'pouce', 'pied', and 'double-yard' for a reason. Other socieities and cultures used measures named after body parts for a reason.

The criticism is rightly made that these measuring schemes are open to variability, but that is an issue of precision, not utility ; but over the last quarter of a millennium, variations in the length of a yard (36 inches) due to definitions have been of the order of +/- 0.001". In practical terms, insignificant. That these (Imperial) measures arose because they were human and therefore useful-sized is pretty indisputable.

The meter was defined by drawing two lines on a bar of metal

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It wasn't. It was defined originally as a fraction of the quarter-circle passing through Paris. Subsequent definitions involved the length of a seconds pendulum. A metal rod was used to provide a reference length. Exactly the same was true of the yard, whose reference length was the length marked between two lines on a gold bar held by the Exchequer. Increases in precision have been due to technology, not some inherent superiority of metric measure.

and saying that the distance between those marks would be the meter. No unclear my-foot-is-bigger-than-yours "human sized usefull measurements".

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The issues relating to the precision of Imperial measurement in the yard were identical to those in establishing the precision of the standard metre, both being set as either the length of a seconds-pendulum swing or the length of a metal rod at standard temperature and pressure.

The advantages of metric are many. It is precise, it is (relatively, but not entirely) unambiguous, it lines up closely with the human basis of calculation. It makes good sense because computing with large quantities is as easy as computing with small or infinitesimal quantities. Millions of people use it without problem, because they are formally taught how to use it.

However, the notion that Imperial measures made sense because they corresponded to human experience is not even 'slightly flawed', it's a piece of anthropic metrical history. There are proper criticisms to be levelled at the Imperial system. This isn't one of them.

All I can say regarding metric vs imperial systems is... (and having skipped over much of this thread) As a lad who has never known anything other than metric, the various names and units that imperial uses, sound very strange and weird to me! All the names for metric units have a logical progression but the imperial names don't seem to relate to each other in any way!!!

alexmacphee said:

The inch was redefined in 1959. What it was before that was perfectly clear, and standardised.



I cannot see where it has been shown, as opposed to asserted, that the correspondence of measures to 'human useful-sized measures' is "flawed".

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The many different units called foot, thumb, etc., giving cause for acts, defining what these thingies should be, the last as late as 1959, should not have escaped you.

alexmacphee said:

It wasn't. It was defined originally as a fraction of the quarter-circle passing through Paris. Subsequent definitions involved the length of a seconds pendulum. A metal rod was used to provide a reference length. Exactly the same was true of the yard, whose reference length was the length marked between two lines on a gold bar held by the Exchequer. Increases in precision have been due to technology, not some inherent superiority of metric measure.

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You mix up what they imagine a meter would represent with how long they said the thing was.

The same error that you exhibit above: it is perfectly clear why people pace things off, etc. No problem there.
The problem arises when two people do the same, i.e. when that is used as a common unit of measurement.
We do not need to know what a unit represents, but how big it actually is.

alexmacphee said:

However, the notion that Imperial measures made sense because they corresponded to human experience is not even 'slightly flawed', it's a piece of anthropic metrical history. There are proper criticisms to be levelled at the Imperial system. This isn't one of them.

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And just because it is "a piece of anthropic metrical history" it is flawed.

We need governments and other bodies to tell us how long our feet are, how broad our thumbs are, how long our stride, etcetera, to turn a system based on such thingies into something usefull, good enough to build, say, space telescopes.

cmacd123 said:

That is the beauty of it all.. JUST MOVE the DECIMAL. A US Inch is legaly defined as 2.54 CM. so a CM is slightly less than a half inch. Each Cm has 10 MM. much smaller than an eighth, more like a 16th.

Your eighth of an inch is about 3 MM. (1/8 is .125 inch) 2.54Times .125 is 3.175MM

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You're missing my point, perhaps because I'm making in the English way with tongue slightly in cheek. The metric units jump down by a factor of ten, from centimetres to millimetres and up by a factor of one hundred (unless you include the decimetre, which I've never seen in my local hardware store!) from centimetres to metres, giving increments which are frequently clumsy and impractical. The imperial system lends itself to binary division to reach any degree of accuracy required.
Tellingly, as I look now at a metric rule, it has a longer mark every five millimetres, so even the metric system gives a nod to Base 2 with half-centimetre increments!
Steve

Q.G. said:

The many different units called foot, thumb, etc., giving cause for acts, defining what these thingies should be, the last as late as 1959, should not have escaped you.

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I'm not sure I understand the point you are trying to make here. Legal acts also define the metric measures, that's a requirement for weights and measures purposes in all jurisdictions. There is no difference here. In 1959 the yard was 'regularised' to the existing definition of the metre. In 1960, the metre was 'regularised' to something else. A fact which may have escaped you.

You mix up what they imagine a meter would represent with how long they said the thing was.

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I am not mixing anything up. There have been several definitions of the metre. Someone didn't wake up one day, draw two marks on a rod of platinum, and say 'This is a metre, we'll use this length as our standard'. It was originally defined as one ten-millionth the length of the great circle from the pole through Paris to the equator, a definition chosen over the competing definition based on the force of gravity because gravity varied over the surface of the earth. It was an analytic measure, not a synthetic one.

Had there been rather more scientific foresight about the length set, it would have been possible to define the metre in such a way that 'natural' physical constants came out as whole numbers, a reasonable argument to make given that the advantage of the metric system is, as I have acknowledged earlier, computability. For example, the metre could have been defined so that the acceleration due to gravity was 10 m/s/s at the equator, instead of 9.81m/s/s. Or the metre could have been defined so that the fundamental constant of the universe, c, computed as a whole number instead of a very-nearly whole number.

The same error that you exhibit above: it is perfectly clear why people pace things off, etc. No problem there.
The problem arises when two people do the same, i.e. when that is used as a common unit of measurement.
We do not need to know what a unit represents, but how big it actually is.

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I am not making any error here about standardisation. The basis of Imperial measure is in things like human activities, but these have been standardised at least as long as the metric system has. Ancient Roman surveyors and roadbuilders measuring distances used ropes or straps attached to their ankles with a reference length of five foot to run out the distances in such a way that the distance run did not vary with different stride lengths due to different leg lengths. If you seek to give the impression (and I do not wish to misrepresent you, so put me right if I'm mistaken) that until 1959, people were using inches whose lengths could vary significantly, then you're mistaken. The precision to which the inch was standardised was no different form the precision to which the metre (or centimetre) was standardised -- indeed, how could it be otherwise with the same technological context? Whilst earliest definitions of the inch were based on the dimensions of the thumb, the earliest 'legal' definition was based, not on the dimensions of one thumb, but on an average taken from a range from smallest to largest. To anyone familiar with the central limit theorem, this is going to result in a pragmatic definition of an inch that takes it some way from the variability of individual thumbs. So our ancestors had a pretty shrewd idea of the importance of standardisation and of being aware of the consequences of variability.

And just because it is "a piece of anthropic metrical history" it is flawed.

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You haven't shown this, you've merely repeated it. Your argument was that the assertion Imperial type measurements "made sense" because they were related to human experience was "seriously flawed", and to do this, you would have to show that such measurements were chosen for other reasons that relation to human experience. You may make observations on the nature of precision and accuracy, but that's a different matter entirely.

The metric system reminds me of the decision by Ilford (see, we can steer back on topic!) a few decades ago to re-label their fibre and RC paper surfaces (matt, glossy, pearl etc) using a letter code so chosen that it did not start any of these words in any common language, so that any aide-memoire in one language wouldn't accidentally refer to a different surface texture in another language. It was, in a real sense, un-ergonomic, and by intention. To this day, I cannot remember which surface is represented by code 44M.

The metric system's advantage in ease of computability is countered by its un-ergonomic appeal in everyday use. Three-quarters of eight ounces is easy to calculate with little effort ; three-quarters of two hundred and fifty grams isn't.

We need governments and other bodies to tell us how long our feet are, how broad our thumbs are, how long our stride, etcetera, to turn a system based on such thingies into something usefull, good enough to build, say, space telescopes.

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I'm not sure how this differs for any other system of weights and measures.

alexmacphee said:

Quote:
We need governments and other bodies to tell us how long our feet are, how broad our thumbs are, how long our stride, etcetera, to turn a system based on such thingies into something usefull, good enough to build, say, space telescopes.

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I'm not sure how this differs for any other system of weights and measures.

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It doesn't.

That's the point: just using the length of your arm is no good.
See?

Q.G. said:

It doesn't.

That's the point: just using the length of your arm is no good.
See?

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No, I'm afraid I don't. The point you are attempting to make is eluding me, and it's not for the want of reading as closely as I can.

It's quite simple, if you allow yourself to slip out of the i'll-defend-my-patch-come-hell-or-high-water mode.

Units are used so that i know how long to cut a piece of wood if you say you want a piece of wood of a certain length, and you do indeed want that piece of wood to be the length you need it to be.

Write me a letter, saying it is three and a quarter times the length of your foot, and i'll either have to use the length of my own foot (the old situation, created by "anthropic metrical" systems), or write a letter in reply, asking to put two marks on a piece of paper, so i know how long your foot is (the Acts of Parliament needed to clear up the mess "anthropical metrical history" created).

If you had send me a letter, with the length of the piece of wood you needed marked on it (i.e. a defined unit, like the meter, and not a derived unit, like the/your foot), you and i wouldn't need to worry about whether you have a bigger one than i, and i could just cut the piece of wood to size, and we'd be both happy.

Deriving units from variable, "anthropometric" thingies goes against the thing we need units for (how long did you need that piece of wood to be again?), and the mess it creates can (as it has) only be resolved by changing them from "anthropometrically" derived units into defined units.
"The assertion that measurements make sense because they "correspond to a human-sized useful measurement" is seriously flawed."

If you guys want to continue this, I suggest a new thread. It's interesting, but OT for this one.

Love,

J

JBrunner said:

I suggest a new thread. It's interesting, but OT for this one.

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Are you able to split it off using the 'under the bonnet' admin controls, so that the history is kept intact?

I appreciate it may not be considered worth the effort, in which case, no harm done.

JBrunner said:

If you guys want to continue this, I suggest a new thread. It's interesting, but OT for this one.

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I agree.
I think everything has been said about the unit thingy, so no need to entangle the two threads.

alexmacphee said:

Are you able to split it off using the 'under the bonnet' admin controls, so that the history is kept intact?

I appreciate it may not be considered worth the effort, in which case, no harm done.

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I don't have time at the moment to do that myself, but if one of the other moderators would like to, it's not a bad idea, and it isn't that hard to split a thread.

Send me a PM, if you need instructions. (Short version: Check off all the posts to go into the new thread, across multiple pages okay, then select "move posts" from the moderation menu at the bottom of the thread, and you'll get a menu to create a new thread or move them into an existing thread.).

"traditional enthusiast" is a bit of an oxymoron.

Tradition implies it's been around a long time. The passing down of elements of a culture from generation to generation, especially by oral communication.

An enthusiast is one who is filled with enthusiasm; one who is ardently absorbed in an interest or pursuit.

Personally I find it hard to get enthused about something that's been around a long time.

Q.G. said:

I think everything has been said about the unit thingy, so no need to entangle the two threads.

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If you think it's run its course, then we can let it go at that. It was engaging enough that I rather forgot where it was and let myself get carried away with the interesting flow of the discussion. There was no intention to strain the tolerance of the moderators.

Either way, it's been a pleasure.

Q.G. said:

Deriving units from variable, "anthropometric" thingies goes against the thing we need units for (how long did you need that piece of wood to be again?), and the mess it creates can (as it has) only be resolved by changing them from "anthropometrically" derived units into defined units.
"The assertion that measurements make sense because they "correspond to a human-sized useful measurement" is seriously flawed."

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You seem to be confused about how long English units have been well defined. My CRC Handbook of Chemistry and Physics from 1932 has very specific and well defined definitions of both English and Metric units, and specific conversions to allow one to convert between the two systems.

There was no confusion of English unit amounts as they had been long defined for commerce.

IF you want to really learn the details of this history, see:
http://physics.nist.gov/Pubs/SP447/contents.html