Gareth's Downstairs Computer wrote on 8/5/2017 9:57 AM:
On 05/08/2017 14:34, Chris wrote:

Exactly. The control is single path, master to slave, with no feedback
to the reference, making it an open loop design. The master has no
knowledge of the state of the slave at any time.

Untrue.

The matter starts off when the slave signals to the master and drops
the gravity link in the master, then, when the master pendulum is in
a position to accept the impulse from that dropped gravity link, it
signals back to the slave

But ... I'm still trying to google for the exact mechanisms because
most URLs only hint at what is happening. (I'm also awaiting delivery
of a couple of hope-jones' books about electric clocks)

What you are describing is how the phase measurement of the master is made.
The gravity lever is simply a remontoire providing a consistent push to
overcome the force of friction. It is designed to be invariant of small
changes in timing of its release. You can see that in the animation linked
below. The gravity arm is released at the point when the wheel is directly
under the end of the gravity lever. A small change in timing changes the
force only a tiny amount. This is critical to maintaining the swing of the
free pendulum without affecting its period.

http://www.chronometrophilia.ch/Elec...cks/Shortt.htm

The animation happens in real time so it is hard to see the details of what
is going on. The gravity lever and accompanying control is the magic of the
clock. The rest is pretty straight forward. You need Flash to view this
page. There is a button to see the wires.

--

Rick C