Dear Roger,
As your reference to French Revolutionary Time
says:
The hundredth part of the hour is called
decimal minute; the hundredth part of the
minute is called decimal second.
With 10 hours in the day (one mean Earth rotation
with respect to the sun) this gives:
10x100x100 = 100000 seconds in a day
The scheme we are more accustomed to has:
24x60x60 = 86400 seconds in a day
This suggests some attempt not to disturb the
definition of a second too much, though I doubt
such niceties would be high on Napoleon's agenda!
In your earlier message you noted...
This would allow clock makers to just change
the face of the 12 hour clock to a 10 hour
clock. Otherwise the gears would have to be
changed to give a 24 hour, 10 Republican hour
clock.
Alas, rather a lot of modifications would be
required to upgrade (downgrade?) the clocks.
A two-second pendulum (one tick per second)
would have to be shortened from about 25cm
to about 19cm and the gearing from the
escapement would need to be modified so
that the second-hand rotated once per 100
ticks and so on.
I should be very surprised if many small
clocks were modified, though I suppose a
few prestigious large ones might have had
the treatment.
A painted sundial would be relatively easy
to modify. Any constant-declination curves
could stay undisturbed. Only the hour lines
would need to be altered.
Of course, engraved or stone-cut sundials
would be vandalised by such a process.
In my view, the best thing that happened to
Napoleon was having the opportunity to study
the sun at latitude 16 degrees south when he
had considerable leisure time on his hands!
Frank
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