Talk:Grain (mass)

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[edit] Confusion around weights of physical grains

64 wheat grains were set to weigh as much as 45 (barley) grains, when used as a unit. That makes one wheat grain 92.158449…7 mg by modern conventions.

The math doesn't work out. If 64 wheat grains is equal in weight to 45 barley grains, then the wheat grain would weigh less than the barley grain. Either the weight of the wheat grain is wrong, or the ratio is wrong (perhaps it should be 45 wheat grains to 64 barley?). I don't know which is correct, so I can't fix it. Nik42 21:05, 22 August 2006 (UTC)

Different meanings of "grain". I'll disambiguate. Gene Nygaard 11:56, 17 October 2006 (UTC)
As the previous version was immensely confusing (I was confused myself) I repaired it with the knowledge I gained after sifting through several coin-related sites. The real barley and wheat grains are currently in the range of metric grain, i. e. 50 mg, and at the time of establishment of grain-based standard weighed even less - ca. 45 mg. There are almost no variety of grain (except for some experimental hybrids) that would demonstrate such high weight as 64,8 mg, so it is SURELY not the real barley grain that is referred to here. 78.60.54.188 (talk)

Something seems to be wrong. I have verified that the "1000 kernel weight" of modern barley is in fact typically in the range 30-45 g. It seems that the barley kernel is what we mean by the grain here. (Or does obtaining the kernel involve some non-trivial peeling process?) So apparently average barley grain masses are 30-45 mg. Similarly, average wheat grain masses are 30-40 mg.

This does not seem to fit with the conventional wisdom of historians that 4 wheat grains or 3 barley grains make a carat or siliqua, i.e. about 190 mg. So what's wrong? My guess is that mediaeval grains were even smaller, but that the largest grains of an ear (which is what we are directed to consider) are considerably heavier than the average. --Hans Adler (talk) 19:29, 7 April 2008 (UTC)

  • There have been hundreds of years of selective breeding since then. Phlegm Rooster (talk) 02:24, 8 April 2008 (UTC)
So what did they select? My guess is that the farmers were interested in large average size of the kernel, and in relatively uniform kernels. The maximal kernel size within an ear could theoretically even have gone down, although I doubt it. What I would like to know is: What's the typical weight of the largest kernel in modern two-row barley? (The analogous questions for wheat are interesting as well.) --Hans Adler (talk) 10:17, 8 April 2008 (UTC)
Beyond selecting for yield per unit area of land planted, I don't know. But if one selected for ease of threshing, for example, it might change the grain size inadvertently (this is called pleiotropy). I'll look into this a bit. Phlegm Rooster (talk) 07:20, 9 April 2008 (UTC)

[edit] Paris grain?

According to

Philip Grierson. 1965. Two Byzantine Coin Hoards of the Seventh and Eighth Centuries at Dumbarton Oaks. Dumbarton Oaks Papers 19: 207-228.
"... the Roman tremissis of 1.5 g accorded ill with the Germanic weight systems based upon the grain, whether the barleycorn—the later Troy grain—of 0.064 g or the lighter wheat grain of about 0.050 g."
and then continues in a footnote:
"The weight to be assigned in the early Middle Ages to the wheat grain as a metric unit is uncertain and no doubt varied from place to place, but it was about this figure. The generally accepted proportion between the barleycorn and the wheat grain of 4:3 would put it at 0.048 g, which was in fact the weight of the latter grain in the Low Countries, but the Paris grain, which was equally based on the wheat grain, was slightly higher (0.052 g)." Phlegm Rooster (talk) 08:21, 9 April 2008 (UTC)

Yes, something like 50 mg for wheat and 64 mg for barley are the generally accepted numbers among historians, or have been until recently. (I don't have much experience with researching historical publications.) But it is important to keep in mind that the "grain" as a unit of measurement was really just that. Actual weight pieces for such small weights were probably pieces of metal or carefully selected grains of the right weight. So there is a lot of leeway because of natural variability (see carat (mass) for sources on the analogous problem for carob seeds), the only question being whether it's enough to be plausible. I have found one paper where a historian (more than a hundred years ago) had made an experiment. He weighed the two kinds of grain from the same field and got the 4:3 proportion stated in ancient texts. But he said nothing at all about the absolute weights.

I think it's very unlikely that the heavier grain unit in Paris had anything to do with biology. Very likely they had some reason to choose a new standard weight that was slightly heavier than usual and decided to divide it in the way that they were used to. Apparently the normal method in such a case was to adapt the number of ounces in a pound and the number of grains in an ounce until you got away with the grain weight that everybody else used. If there was no nice solution, i.e. no solution that avoided factors of 7, 11, 13, ..., then it would have been logical to make an exception. Or it could just have been the whim of some king. Even without any physical grains to match the grain weights, the main problem would have been loss of compatibility with other weights. --Hans Adler (talk) 09:34, 9 April 2008 (UTC)

  • These measures had to be accessible to the ordinary people, who needed to be sure they weren't getting ripped off. Therefore it is much more likely that they were using the actual grains whenever calibrating scales, not small pieces of metal. Why else would they specify "from the middle of the ear" all the time? The heavier grain in Paris had something to do with that wheat being heavier, but my source did not say how that could be. Phlegm Rooster (talk) 09:51, 9 April 2008 (UTC)

But that really depends on what the weights with the heavier grain were actually used for. There were lots of local standards, perhaps precisely because the average grain weight depended on the region. But here we are talking about influential standards that were actually used in minting money. Of course one could argue that this was such a local standard, one that somehow became more important. (And then of course it doesn't seem very likely that they actually counted 5000-10000 grains "from the middle of an ear" to find out how much a pound is.) In the past some very strange claims were made, such as "the king's foot" being the actual length of the king's foot and changing with every new ruler. I haven't researched this (I am just interested in weights right now, although this may change), but I guess that this has been rejected later. Sometimes a "foot" was considerably more or less than the average length of actual feet, and I see no reason why it shouldn't have been the same with weight units. For standardised weights such as the Roman pound (which remained constant over many centuries and was used all over Europe) and their subdivisions, that is. --Hans Adler (talk) 10:18, 9 April 2008 (UTC)

Pehaps, but counting 24 grains to get a pennyweight, and multiplying that by 20 to get an ounce (480 grains) and again by 12 to get a troy pound (5760) is not all that unbelievable. And if gold was on the line, counting to 480 isn't really a big deal. Phlegm Rooster (talk) 17:33, 9 April 2008 (UTC)
Are you able to access the scientific/historical literature online (are you at a university campus)? I'm looking at articles written in the 1700/1800s, which say very interesting things. I think that older sources are better. Historians in Victorian and later periods had a very anti-middle ages bias, and basically assumed that scholars in the middle ages were idiots. So they tended to make stuff up, which of course is bad for us. Phlegm Rooster (talk) 16:59, 9 April 2008 (UTC)

Right now the answer is no, because I am at home. But when I did some research from work I could access about 2/3 of the history oriented papers that I was interested in, and I think all of the really old ones. So if you give me a list of papers that you think might be interesting, or suggest some search terms, I will have a look. --Hans Adler (talk) 17:05, 9 April 2008 (UTC)

Okay, and keep in mind that I am a biologist, not a scholar of this field, so I am not wedded to a particular belief system, except to say that there are many possible sides to this story, and I am skeptical that the answer is fully known. For example, in Simpson, A. D. C and Connor, R. D, 2004. The Mass of the English Troy Pound in the Eighteenth Century. Annals of Science 61 (3): 321-349, page 329:
"From English usage and from Pegolotti’s account, we know that the ratio of the size of the English troy ounce (or the Bruges silver ounce) to the English tower ounce (or Cologne ounce) is 16:15, the ratio of Paris ounce to the Cologne ounce is 21:20, and the ratio of the eight-ounce Paris and Bruges gold mark to the six-ounce Bruges silver mark is 21:16.35 If these ratios are precise (and it is part of our purpose here to demonstrate that this is so) then, in terms of English troy grains, the Paris ounce is accurately 472.5 grains, and the tower or Cologne ounce is 450 grains, where the English troy ounce at 480 grains defines the troy grain."
So the historical debate is ongoing, and the best course of action for us at Wikipedia is to just report on that, never losing track of the current definition (people pack explosives based in it). Phlegm Rooster (talk) 17:26, 9 April 2008 (UTC)
The same source goes on to find that the troy pound varied from 6998 to 7004 grains over the years. Worth reading, in any case. Phlegm Rooster (talk) 17:40, 9 April 2008 (UTC)

Thanks for the pointer, I don't know how I could miss that! Now I have also read the relevant chapters of "Weights and Measures in Scotland", by the same authors. The paper is really just about a detail that didn't fit into the book because it wasn't really connected to Scotland. The book itself had to explain why the well-known old definition of the pound (the Tower pound, to be exact), which exists in parallel versions both in England and in Scotland, talks about 32 wheat grains, when the real subdivision was into 24 barley grains. An old English version says: "... so that an English Penny, which is called the Sterling, round without clipping, shall weigh Thirty-two Grains of Wheat dry in the midst of the Ear; Twenty-pence make an Ounce;...". The version of the Scottish king has only survived indirectly in a later text that was adapted to a new standard: "King David ordained that the sterling should weigh 32 corns of good and round wheat... The ounce in King David's time contained 20 good and sufficient sterling pennies...".

They explain this as follows: "The wheat corn, the barley corn, and the carob seed have conventional weights assigned to them in metrology – four wheat corns are understood to weigh the same as three barley corns and both are equivalent to one carob seed[...] Experiment has shown that the relative weights of large wheat and barley corns are remarkably well described by the conventional 3:4 weight ratio, but both wheat and barley corns are very hygroscopic and their actual weights are variable and highly dependent on moisture content. [...] As for the Tractatus statement that the penny weighed 32 wheat grains, Grierson notes that this 'was indeed never valid for England but was an expression of truth for the Carolingian penny'." They argue that this part is not to be understood literally, but expresses the fact that this is based on an earlier French standard, by just copying the definition of that standard, or something like that. There seems to be more on this in the older book by Connor ("Weights and measures of England"), which I haven't got hold of yet. Perhaps that book can convince me that the 3:4 ratio really makes sense; and perhaps Grierson ("Money and coinage under Charlemagne", in "Karl der Große: Lebenswerk und Nachleben", 1965-8) can convince me that the magnitude is approximately right (if I have access to that). --Hans Adler (talk) 13:16, 11 April 2008 (UTC)

So do you see any need to change the article? Phlegm Rooster (talk) 18:17, 11 April 2008 (UTC)

Yes. It contains incorrect (and unsourced) information; and it is generally a big mess, mixing US-centric and international, modern and historic viewpoints. I will try to disentangle this. --Hans Adler (talk) 20:04, 11 April 2008 (UTC) OK, I have done it. I moved the diamonds stuff up into the lede, but I have gone to some lengths to make the milligramme value of the troy grain much more prominent and hide that of the metric grain. --Hans Adler (talk) 22:44, 11 April 2008 (UTC)