Antique Clock Collecting: Connecticut Styles : Antique Clocks: Mercury Pendulums


We need to talk about Mercury Pendulums because
you’ll find them in French Crystal Regulators, as you heard about before or in certain “true”
regulators, large wall clocks that you might find out there. In this case, we’re looking
at a French Crystal Regulator Pendulum and the Mercury inside there, as in all these
Mercury compensating pendulums, is designed to compensate for temperature changes. This
is not to look pretty, this is, actually has a function. Because, we talked about Pendulum
clocks, why they work, because the pendulum of a fixed length swings at a fixed rate.
But with a temperature change, that’s the Pendulum Rod can actually get longer if it
gets hotter in the house, or shorter if it gets colder. If it gets longer, you have a
longer pendulum, the clock slows down. So a way, one way to counteract that, is to actually
have two tubes of Mercury inside and as the temperature heats up, our pendulum wants to
grow longer and slow down. But the Mercury inside wants to expand upwards and if you
have the right amount of Mercury in there, the amount that expands upwards compensates
for the amount that the pendulum grows longer and you maintain accuracy. In large pendulum
wall regulator clocks, you’ll often see very large Mercury Pendulums can have ten, fifteen,
sixty pounds of Mercury in there. So, obviously, you want to be careful with those, but often
they’re an important part of a large, collectible wall clock, if you retain the original Mercury
Pendulum with its glass vials to let you see what’s inside.

2 Replies to “Antique Clock Collecting: Connecticut Styles : Antique Clocks: Mercury Pendulums”

  1. I own a French clock with just such a mercury pendulum that can be seen. It is my understanding that in 1775 they began covering the pendulum with a filigree plate so the pendulum could no longer be seen. Is there anywhere I can get an estimated value of my clock? Thanks you.

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