The message
from "nightjar" cpb@insert my surname here.me.uk contains these words:

Chuck the book away then as it wasn't the French.

Who, then, in your opinion did originate the metric system, if not the
French Academy of Sciences at the request, in 1790, of the National
Assembly?

That seems to be the widely held view but a search I did found a site
(http://lamar.colostate.edu/~hillger/dates.htm) that gave the initial
credit for the metric system to a French vicar in 1670 (still French of
course)

While Gabriel Mouton is claimed to be the spirtual father of the metric
system, his base unit of length would have been the swing length of a
pendulum with a frequency of one beat per second, which is roughly 25cm. He
did, however, provide the central ideas that were developed by later French
scientists.

You sure about that. I haven't looked up Mouton but I would have thought
a 10" pendulum would have been a one second pendulum - ie one complete
cycle or 2 beats a second. Grandfather clocks have 2 second pendulums
and tick once a second.

but credited a first mention of a decimal system to Simon Stevin
(a Flemish mathematician and engineer) in 1585.

I would view a defining quality of the metric system to be that is based
upon the metre, rather than simply being decimal. Otherwise, the centimetre
/ gram / second system I was taught at school (along with the metre /
kilogram / second and foot / pound / second systems) would be equally
qualified for the name.

I think you and I might be much the same age but I was taught that the
cgs system was metric. ISO metric only dates back to 1960.

Incidentally at what stage did you come across the slug? I never saw as
much as a mention of the unit until I got to college.

"1790

Thomas Jefferson proposed a decimal-based measurement system for the
United States.

Interestingly, that seems to have been based upon Mouton's work,
rather than
on the system then being developed in France.

France's Louis XVI authorized scientific investigations aimed at a
reform of French weights and measures. These investigations led to the
development of the first "metric" system."

It is more usually credited to Talleyrand and the French Revolutionary
National Assembly

The Bastille fell in 1789. In 1790 Louis XVI still had his head but not
his liberty but he could have authorised the start of the work the year
before or even earlier. It wouldn't have been finished overnight. The
French revolution could even have delayed the introduction of the metric
system.

--
Roger Chapman