Interesting summary. I'd like to challenge one fact, comment on another, and
finally add some facts from a US perspective that reinforce several of the
points you made.
*I find it very difficult to believe in 1814, the inch was legally defined as
three grains of barley. I suspect that was more in the spirit of "Hey, kids,
make your own standards at home" much like the equivalence of 1 L of water and
1 kg -- a useful approximation, but not entirely accurate.
*Your numericana reference has a link to the text of the 1819 Commission whose
report eventually became the Imperial system. It makes two points:
-The relative multiples and submultiples of each unit of measure were well
established and recommended to continue, therefore 36" = 3' = 1 yd was already
established; none were changed in 1824, or first defined.
-It refers to a brass standard yard made in 1760 by Bird, it also refers
vaguely to a second standard, and I am not sure which was chosen. However,
they clearly related their recommended standard yard to a seconds pendulum,
measured to be 39.1372" by this scale, and to the metre, 39.3694". I believe
whichever of the two existing standards so measured became the 1824 Imperial
yard, later destroyed by fire. The comparison to the metre gives 1 yd = 0.914
415 76 m. Note that the seconds pendulum definition differs from the 1855
value. However, the length of the day changes over time, and I am not sure how
well the concept of "mean sun" was defined in this time period. The actual
time of the sun crossing the meredian varies seasonally throughout the year
(equation of time).
The US info is all from NIST SP447. Our early weights and measures history
reads like a third world nation's. Congress did little to assert its authority
over weights and measures until 1827 when a standard troy pound was obtained.
Individual states had their own standards and NIST charitably describes them as
" more or less authentic copies of the English standards." In 1832, it
declared the span between the 27th and 63rd inch markings of the Troughton bar
as the US standard yard (this 82" bar had been brought to the US in 1815
following the War of 1812.). I assume this relatively central section was the
best fit to the British yard of the time.
The US also had an early iron meter bar brought to the US by Hassler in 1805.
It was used for all Coast Survey work until 1890, but apparently never compared
to the yard. It was one of several prototypes made by the Archive of the Metre
(referred to as Committee Meter in the US)
The second US standard yard was the bronze #11 yard obtained in 1855. It
apparently measured well against the Imperial yard at the time. The Troughton
bar was measured against it and the Troughton yard determined to be 0.00087"
long relative to the new standard. Bronze #11 was compared to the Imperial
yard in 1876 and 1888. Discrepancies were noted, and the US felt they were not
entirely due to #11. This fits with the "shrinking Imperial yard" you noted.
Bronze #11 was measured in 1893, just before the Mendenhall order at 0.914 399
80 m against the US's prototype meter received via the Treaty of the Meter.
Assuming no aging of either the Troughton bar or bronze #11, this would place
the Troughton yard at 0.914 421 90 m, using mixed 1855 and 1893 data. This is
close to the length used by the 1819 Commission.
In spite of the measurement above, the Mendenhall order made a statutory
declaration that the meter was equivalent to 39.37" (1 yd = 0.914 401 83 m).
This was known to be wrong, but thought to be sufficiently accurate and easy to
remember. It was used until 1959 (and still used for Survey foot). I think it
is obvious that had they chosen the reciprocal relationship with the same
considerations, they would have used 1 yd = 0.9144 m.
Note: I followed the lead of these articles and use 8 figures in the values of
the yard. However, I doubt they could measure to 10 nm at the time, and some
decimal dust is involved. With interferometry, they would be hard pressed to
measure 1/10 wavelength or around 50 nm.
From: Pat Naughtin <pat.naugh...@metricationmatters.com>
To: U.S. Metric Association <firstname.lastname@example.org>
Sent: Mon, December 28, 2009 12:41:02 AM
Subject: [USMA:46309] Re: YouTube metric
On 2009/12/28, at 01:04 , John Frewen-Lord wrote:
>Well, it was a bit interesting, if somewhat childlike in its presentation.
>>Pity that in the last segment, when explaining that there are 1000 m in 1 km,
>>they sort of treated the m and the km as two discrete units, rather than
>>simply one unit with a prefix.
>>Still, progress of sorts! Interesting that NASA seems to be promoting this,
>>when we all know that they are as much the villain as anyone in resisting the
>>US's conversion to the metric system.
I agree with you about the distinction between metres and kilometres. I am also
intrigued by the NASA sponsorship.
I also had a concern about the underlying assumption that 'there are two
systems of measurement' as I don't think that this is true.
There is certainly a metric system but to my way of thinking there never was a
single previous system of measuring units. My analysis of the old pre-metric
situation is that they were more or less randomly generated collections
of measuring words that were more or less associated with measuring activities.
As an example, consider the inch.
Prior to the defining of the metric inch, in 1959, as exactly 25.4 millimetres,
the inch had many different definitions that included the width of a thumb, the
length of three grains of barley, dry and round, placed end to end, lengthwise,
1/3 of a palm, 1/4 of a hand, 1/12 of the foot of St Paul's, and 1/36 of the
distance between King Henry I of England's nose and his thumb.
More formally, legal definitions of the UK inch have included:
1814 three grains of sound ripe barley being taken out the middle of the ear,
well dried, and laid end to end in a row
1819 A preliminary yard was made in anticipation of the Imperial yard in 1824.
This yard has been precisely measured as 39.3694 inches to a metre which means
that each inch was about 25.4004379 mm.
1824 1/36 of an Imperial yard. This yard was precisely measured as 914.398416
metres giving an inch of 25.399956 mm. Note this was the first Imperial
measure; earlier measures were not legally 'Imperial'.
1834 The British Standard yard was destroyed in a fire when the British Houses
of Parliament burnt down. The inch was destroyed along with the yard.
1841 New standard yards were made. Unfortunately, as a standard, the metal
chosen for these standard yards (Baily's metal) began to shrink. In:
* 1895 the inch was 25.399978 mm
* 1922 the inch was 25.399956 mm
* 1932 the inch was 25.399950 mm
* 1947 the inch was 25.399931 mm (See
http://home.att.net/~numericana/answer/units.htm and search for nara)
1842 a standard inch measure was kept in the Exchequer chamber, Guildhall, and
that was the legal definition of the inch.
1855 1/36 of a standard yard defined as the length of a 36 inch yard derived
from a seconds pendulum beating 86 400 times between two meridians of the Sun.
The pendulum was held in a vacuum in a temperature controlled chamber at sea
level in Greenwich, London. The length of this pendulum was 39.1392 inches
(about 994.1357 mm).
1878 A new physical standard yard was made and this remained the UK Imperial
standard until 1964.
1964 The Uk legally adopted the metric inch, of exactly 25.4 mm, as the
Imperial standard inch.
During this time, while the length of the metre and hence the millimetre
remained constant, there has been a wide range of changing values for the
different UK inches – hardly a system!
Note that I have not included all of the other inches that each have multiple
definitions hence multiple different lengths. Here are some of their
names: angulam, anguli, duim, hüvelyk, palec, polegada, polegartum, police,
pouce, pulgada, pulgar, thumb, tome, tommel, and tumme.
And I have not referred to the changing definitions of the legal inch in the
USA at all. This is too complex for me.
Please note that the inch is only one example of old pre-metric measuring
words. Every old pre-metric measuring word can be similarly analysed. You could
begin with: foot, pound, bushel, barrel, ton, etc. etc.
To conclude, I find no evidence for any system before the metric system
formulation as the Système Internationale d'Unités. I have not ignored fps,
cgs, mksA, foot-slug-second, etc. I simply regard them as being attempts to
form a system that failed because they were incomplete and not coherent.
Author of the ebook, Metrication Leaders Guide, that you can obtain
PO Box 305 Belmont 3216,
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has helped
thousands of people and hundreds of companies upgrade to the modern metric
system smoothly, quickly, and so economically that they now save thousands each
year when buying, processing, or selling for their businesses. Pat provides
services and resources for many different trades, crafts, and professions for
commercial, industrial and government metrication leaders in Asia, Europe, and
in the USA. Pat's clients include the Australian Government, Google, NASA,
NIST, and the metric associations of Canada, the UK, and the USA.
See http://www.metricationmatters.com/ to subscribe.
----- Original Message -----
>>From: Pat Naughtin
>>To: U.S. Metric Association
>>Sent: Sunday, December 27, 2009 5:36 AM
>>Subject: [USMA:46304] YouTube metric
>>You might find this interesting:
>>Author of the ebook, Metrication Leaders Guide, that you can obtain
>>PO Box 305 Belmont 3216,
>>Phone: 61 3 5241 2008
>>Metric system consultant, writer, and speaker, Pat Naughtin, has helped
>>thousands of people and hundreds of companies upgrade to the modern metric
>>system smoothly, quickly, and so economically that they now save thousands
>>each year when buying, processing, or selling for their businesses. Pat
>>provides services and resources for many different trades, crafts, and
>>professions for commercial, industrial and government metrication leaders in
>>Asia, Europe, and in the USA. Pat's clients include the Australian
>>Government, Google, NASA, NIST, and the metric associations of Canada, the
>>UK, and the USA. See http://www.metricationmatters.com for more metrication
>>information, contact Pat at pat.naugh...@metricationmatters.com or to get the
>>free 'Metrication matters' newsletter go
>>to: http://www.metricationmatters.com/newsletter to subscribe.