Vacheron Observatory Chronometer

[tick talk]

Hello All: I recently aquired an Observatory Chronometer and embarked on a research project to establish some history. What better place than the NAWCC website to record what I learned!

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This Vacheron & Constantin 18k yellow gold keyless pocket chronometer with Guillaume balance was awarded a “Bulletin de Iere Classe aux IIIeme Prix au Concours de Geneve” from the Geneva Observatory and a “Class A Chronometer Certificate” from the Kew Observatory.

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This particular movement, as adjusted by C. Batifolier, was tested from November 16 to December 30, 1912, at the Observatoire de Geneve and scored 733 points out of a possible 1000. This ranking achieved a 3rd Prize classification in the annual Concours. Mr. Batifolier was especially regarded at Vacheron & Constantin after obtaining 1st prize for the manufacturer at the Geneva trials of 1898.

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It was then sent by train to the Kew Observatory and again subject to rigorous testing from January 15 to February 28, 1913. Without a regleur in attendence, it scored 78.7 marks out of 100 and was awarded a Class A Chronometer certificate.

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In 1914, the competition movement and dial were enclosed in a 57mm 18k yellow gold bassine-style case and its awards were proudly engraved on the inner cuvette. It was then offered for private purchase and the new owner added the initials “MHL” to the back cover. I obtained the watch from an American source who could only reveal that it had been in the possession of an Indianapolis family for the past three generations.

The heart of this piece is the 20-ligne gilt brass competition movement, which featured the revolutionary Guillaume balance with gold and platinum poising screws, swan-neck micrometer regulator, and a blued steel Breguet balance spring with double overcoil.

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Charles-Edouard Guillaume was 50 years old when this watch competed with his Anibal composite balance wheel, which he referred to as a Balancier Integral or Integral Balance in English. In 1920, Guillaume received a Nobel Prize for his invention of Invar and Elinvar temperature-stable alloys which further improved timekeeping accuracy. The term “Guillaume balance” was commonly applied to the Integral Balance in recognition of his fame.

Remarkably, the Geneva Observatory can provide copies of the original test documents and a duplicate chronometer certificate (bulletin de marche) for a fee.

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Kew Observatory records are now kept at the Greenwich Observatory Museum and they will provide copies of the test ledgers for free, but unfortunately cannot reissue certificates.

Best Regards, Dean

 

[Dr. Jon]

Lovely!!

Here is something else to add to your files.

Batifolier was very active and later worked almost exclusively for Patek Philippe.

 

[tick talk]

Dr. Jon, that is very exciting!! Are you able to send me larger images or post them here?

 

[Dr. Jon]

The file I made this from is a bit larger but not much better. I can private message a larger version of the file to you.

What is intersting is that your watch did not do particularly well at Kew. A 73 is a very good score, by my calclations about 13 seconds a year in "model error", its shy of the especially good rating and would not have been published in the top performance list. Model error is a way I used to convert a score into a deviation from calculated time. That is, if you know the average rate the watch would be within about 13 seconds of that estimate after a year with about 70% of doing better and 30% chance of doing worse.

The Geneva third is a very good performance and the Geneva test is similar to the Kew test but a bit harder.

At this level , small difference mean a lot and such variation is fairly common in these watches.

BTW is the endstone over the balance blue? Sometimes they do this on high precision watches.

 

[tick talk]

Perhaps Diamond?

The endstone appears clear, perhaps diamond. I didn't notice until you asked - thanks for the prompt!

Please PM me with that larger image.

Your timing observations certainly reinforce the value of a regleur on-hand during competitions. As I recall, watches which scored a minimum 2/3 of available points were awarded Chronometer ratings. Those with top scores were automatically considered for the Concours competitions in Geneva.

Here is a close-up of the jewel in question.

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[Dr. Jon]

So far as I can tell the regleur was never on hand during tests. The watch probably went to him between tests but no observatory would let anyone from the factory near any timepiece being tested.

The difference between a top finisher and an honorable mention was a matter of tenths of a second and they did not have timing machines. It took a week just to get a few rates.

As it is Batifolier did a very impressive job with yours as its Guillaume balance is not that good. Guillaume was a bit of roll of the dice. It required work hardening to gets its final properties and yours was on the poor side. He got around that with very good position adjustments.

Another thing that was probably the limit was the daily variation. This is a measure of how well the watch went together. My decoding of your Kew numbers suggests this was about 0.5 sec per day. That is better than any mechanical watch I have ever tested but the top ones do better than 0.2.

Use the pm feature on this board to send me your email and I'll send you the file.

I doubt the end stone is a diamond. It would be faceted. It still looks blue to me but you are the one with the watch (Rats!!!).

 

[tick talk]

Sapphire endstone!

Well my eyes aren't the best but looking through auction catalogs, I see that many V&C chronometers featured a sapphire endstone. I guess I was expecting something vividly blue, but they all appear very translucent in the pictures.