[Eeeb]

Astronomical regulators were really the first "HAQ". They have a long tradition... and usually exceed the accuracy specs for TC watch movements. (The really good ones have to compensate for gravity variations within buildings!!)

For those that like those sorts of things, there is a post in Clocks on a 1700s London clock you might enjoy. This one is feature rich!! :-! Since it is in a normal longcase case, I suspect accuracy is not it's forte -- but I bet it's as good as a Precisionist ;-)

 

[Hans Moleman]

Astronomical regulators were really the first "HAQ". They have a long tradition... and usually exceed the accuracy specs for TC watch movements. (The really good ones have to compensate for gravity variations within buildings!!)

For those that like those sorts of things, there is a post in Clocks on a 1700s London clock you might enjoy. This one is feature rich!! :-! Since it is in a normal longcase case, I suspect accuracy is not it's forte -- but I bet it's as good as a Precisionist ;-)

That dial certainly looks like the equation of time. It is strange as to why one would need an additional dial for it.
The equation of time is a simple date -> correction table. A piece of paper stuck on the inside of the door would be just as good.

Could it be just an excuse for yet another dial to show the abilities of the maker?

 

[Catalin]

Astronomical regulators were really the first "HAQ". They have a long tradition... and usually exceed the accuracy specs for TC watch movements. (The really good ones have to compensate for gravity variations within buildings!!)
...

I do not know about either of that (TC and gravity) - some MIGHT be calibrated close to TC specs but I doubt that accuracy would hold with the same thermal variation seen in TC wristwatches. And the compensation - that usually has to be done after ANYTHING that involves moving the clock, since the mechanical positioning of it (and generally any mechanical vibrations around) is what changes its performance.

 

[Eeeb]

I do not know about either of that (TC and gravity) - some MIGHT be calibrated close to TC specs but I doubt that accuracy would hold with the same thermal variation seen in TC wristwatches. And the compensation - that usually has to be done after ANYTHING that involves moving the clock, since the mechanical positioning of it (and generally any mechanical vibrations around) is what changes its performance.

The real astronomical regulators never move and sit in temperature controlled environments. Once they are regulated, they do keep very very good time.

"Time and frequency measurements at NIST: the first 100 years" indicates NIST's first pendulum clock kept time to 10 milliseconds per day (== 0.01 spd == 3.5 spy). Not bad for a mechanical device

And this WUS post claims 50 clocks were made in the 60's which were accurate to 2 milliseconds per day.

 

[T5aus]

Just letting everyone know, I have sadly decided to move this magical piece of horological history along, just not a good place for it to be on a surf beach in Queensland. I am not sure if I am able to say where it's listed so in covert speak, it's on the bay. (please delete mods if I am out of line)