Dear John and Jim,
Thanks for the thoughts and for the the Wikipedia reference. I had
referred to this a year or so go but didn't think to go back there
when I was looking for the 'plummet' pendulum. My mistake!
Cheers,
Pat Naughtin
Author of the ebook, Metrication Leaders Guide, that you can obtain
from http://metricationmatters.com/MetricationLeadersGuideInfo.html
PO Box 305 Belmont 3216,
Geelong, Australia
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 [email protected]
or to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter
to subscribe.
On 2009/09/29, at 10:27 , John M. Steele wrote:
The Wikipedia article on pendulums gives a pretty good time line.
http://en.wikipedia.org/wiki/Pendulum
I think the dependence on local gravity would have made it a poor
standard, and not that portable. The gravity dependence (and the
earth's oblateness) was understood (even if not well measured) by
1680.
--- On Mon, 9/28/09, Pat Naughtin
<[email protected]> wrote:
From: Pat Naughtin <[email protected]>
Subject: [USMA:45918] The plummet in metric history
To: "U.S. Metric Association" <[email protected]>
Date: Monday, September 28, 2009, 7:14 PM
Dear All,
Does anyone know anything of the history of the 'plummet'?
Apparently the plummet was used in Wellington's armies as an
instrument to measure the rate at which soldiers marched. The
plummet was a piece of cord attached to a lead shot that was then
used as a pendulum.
Some approximate values are:
1000 mm plummet was used for 60 steps per minute
600 mm plummet was used for 75 steps per minute
300 mm plummet was used for 108 steps per minute
250 mm plummet was used for 120 steps per minute
(The last of these is probably the most common rate used by military
services today)
As the plummet was in common use in 1812, my question relates to how
long before 1812, this pendulum method was in use for military
marching. If this technique was available in 1790, for example, then
it would have had a significant influence on the metric debate about
whether to use the plummet pendulum or the size of the meridian as
the basis for the length of the metre. This debate centred around
Borda who wanted to market his 'repeating circle' and Thomas
Jefferson who favored the pendulum method because of its universal
availability and its portability; sadly perhaps, Borda won that round!
See http://www.gap-system.org/~history/Biographies/Borda.html where
you will find:
When Borda was made Chairman of the Commission of Weights and
Measures, which had as its members Condorcet, Lavoisier, Laplace and
Legendre, he soon put his accurate surveying instrument to good use.
The Commission was set up in 1790 to bring in a uniform system of
measurement. It considered a proposal which had already been made to
the French government to base the metre on the length of a pendulum
which beat at the rate of one second. This proposal had found favour
with Britain and the United States who considered it a truly
international measure. Borda, however, reported on the 19 March 1791
that the Commission had decided on a different standard, namely that
one metre should be one ten millionth of the distance from the North
Pole to the equator. His argument against the pendulum standard was
that it based one unit on another, which might itself change, and
also that the second itself was an arbitrary unit based on the
division of a day by 12 × 60 × 60. Borda argued that the day should
be divided into 10 hours with an hour divided into 100 minutes each
of 100 seconds. Under Borda's leadership the project to accurately
measure the distance from the North Pole to the equator using the
Borda repeating circle was carried out.
Cheers,
Pat Naughtin
Author of the ebook, Metrication Leaders Guide, that you can obtain
from http://metricationmatters.com/MetricationLeadersGuideInfo.html
PO Box 305 Belmont 3216,
Geelong, Australia
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 [email protected] or
to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter
to subscribe.
