Old clock knows it’s slow: slow/fast subdial

[Tiny Iota]

Saw this old clock from the early 1900s yesterday and noticed it was running about 15 minutes slow. So far nothing unusual. Then I saw it had a subdial which showed it was running 15 minutes slow.
So, why would they have this? To know it was running slow, it would have to know the real time and if it knows that, why doesn’t it display the correct time?
It was a cool looking old clock, but this feature made it far more interesting.

 

[Oku]

to me it looks like the hand points to 6, not to 15...
I assume it is either a fine regulation for timing or to adjust the chiming.

 

[JimInOz]

It's not actually indicating the rate. It's to adjust the rate manually.
When you set the clock up, you set it to O, as you notice the main hands gaining or losing time, you adjust the slow/fast to make up for the lost/gained time.

Nice clock though.

 

[Tiny Iota]

Of course it doesn’t show 15 mins!
I thought it did yesterday (after a pint or two) and didn’t look closely at the photo today!

so if it’s for adjusting, why wouldn’t you just adjust the main hands, or is it more of a long term thing in that in those days they knew there could be a +- 20 mins variance in the tolerances so that adjustment dial meant you didn’t have to reset the main hands all the time?

 

[redpcar]

To dial in the beat rate. I like it. Normally not a fan of the big noisy clocks but I would take this one.

 

[Tiny Iota]

If you are, or are with, a former member of the armed services, you can go and see it in the Union Jack Club in London.

Edited: Nov 23, 2019

 

[MCC]

I saw this rather unusual Breguet yesterday




It is called Sympathetique as it is a clock that sets and regulates the associated watch. It belonged to George Iv as prince regent and can be seen at the Queen’s collection.


The watch and clock are linked by a pin fixed behind the clock dial via the cradle. When the pin set off the motion work in the watch, the hands are automatically set to the correct time and it’s regulator is corrected by the degree of inaccuracy registered at the point of synchronisation.

Never seen something like this before.

 

[Professor]

Could be a clock like that was expected to need considerable adjustment on occasion according to ambient temperature and humidity.
I figure those markings were for seconds not minutes.

 

[JimInOz]

The clock was meant to be set in beat with the indicator at zero with the clock set correctly on the wall/mantel/shelf.

Once a week (or preferably, once a month) when the clock was wound, the owner would note how fast or slow the clock was and advance or retard the lever.

Doing it more than once a week would be chasing your tail due to the clock gaining and losing time due to the spring rate.

 

[Evitzee]

MCC

I saw this rather unusual Breguet yesterday




It is called Sympathetique as it is a clock that sets and regulates the associated watch. It belonged to George Iv as prince regent and can be seen at the Queen’s collection.


The watch and clock are linked by a pin fixed behind the clock dial via the cradle. When the pin set off the motion work in the watch, the hands are automatically set to the correct time and it’s regulator is corrected by the degree of inaccuracy registered at the point of synchronisation.

Never seen something like this before.

These were Breguet's tour-de-force, he made about 12 of them. They were made for his best, most influential clients; kings, queens, dukes. One was in a fire decades ago and was considered too damaged to be restored. A young restorer, Michel Parmigiani, stepped up and restored it to its full glory. One of these Sympathique clocks is in the Patek Philippe Museum. They are an incredible piece of machinery and showed the genius of AL Breguet.

A young FP Journe also made one in 1988 for Asprey London in mother of pearl and coral with rock crystal glass.