Unknown escapement

[Kinpol]

Dear collegues,
I'm just restoring the self striking pocket watch with unknown escapement. Do you have any idea what is this?
It works nice, but I've never seen such escapement... The escape wheel looks like Virgule, but it is all...

 

[gmorse]

Hi Kinpol,

I agree, it does look odd, but it appears to work like a virgule. Is there a signature on the watch?

Regards,

Graham

 

[Kinpol]

Hi, thanks for reply,
Yes, there is a signature J.G.Albrecht a Berlin... No. 55

 

[John Matthews]

You might like to compare the escapement with the photographs here.

John

 

[gmorse]

Hi John,

The action looks the same, but Kinpol's staff is more solidly built. A virgule is, after all, just a cylinder which only impulses in one direction. The difficulty of keeping it lubricated probably accounts for its scarcity.

Regards,

Graham

 

[Kinpol]

It gets the impulse in both sides. On the balance staff is something like roller with the wave. The tooth of the escape wheel first gives the impulse on the convex part of this wave, then the next impulse on the concave part of the wave... I don't know if it is understandable... but my english is poor... The tooth slides on this wave...

 

[John Matthews]

Kinpol's staff is more solidly built.

Yes Graham, I agree.

I ran the video at 1/4 speed. It does appear to get impulse in both directions - a double virgule which is shown in a very poor B&W photograph in Clutton & Daniels.

John

 

[Dr. Jon]

My vote is that it is not a virgule.

1) Virgule refers to the comma shaped action piece on the balance staff.
2) A virgule impulses in one direction.
3) The double virgule produces two way impulse

The two way impulse on each escape wheel tooth is the trick of the cylinder so this what I would call it,

Usuallt the impulse in a cylinder is from the curved triangle on top of each post on the escape wheel. This escapement gets impulse from the balance roller. It is analogous to the difference between an English and a club tooth lever.

 

[gmorse]

Hi Kinpol,

When you next remove the balance, please post some pictures of the staff!

Regards,

Graham

 

[Kinpol]

Tomorrow I will... Now I fight with mosquitos...****...

 

[Kinpol]

And here is the roller:

 

[gmorse]

Hi Kinpol,

Thanks, that's most interesting. I can see now how the roots of the teeth engage with the lower, convex part and the tips engage with the the larger, concave part, which acts like a virgule. I wonder if the impulses in both directions are equal? Perhaps Enrico (eri231) has some idea of what this is? He's a fount of much knowledge!

Regards,

Graham

 

[rstl99]

Looks to me like some variant of a virgule-type escapement.
Definitely not double-virgule variant as there would need to be teeth on both sides of the escape wheel.
Isn't it nice to come across something as unusual and original as this, not shown in any of the usual escapement books? Speaks to the creativity of some of the forgotten watchmakers out there....

p.s. Kinpol, great video you shared with us!

 

[Kinpol]

My pleasure...

 

[John Matthews]

Kinpol, great video you shared with us!

Robert - absolutely right - excellent.....

Definitely not double-virgule variant as there would need to be teeth on both sides of the escape wheel.

I am not sure what name to use but I think a double impulse is provided by the single tooth because of the design of the roller and alignment of the escape teeth. Does the 'double' in double virgule, refer to the two sets of teeth or the double impulse?

It appears to me that the impulse given by the tip of the upstanding tooth is as you would expect for a single virgule acting on the portion of the roller indicated by the blue arrow. A further impulse is given by the heel of the tooth acting on the portion indicating by the red arrow.

Here is the sequence as I see it ....





The 'heel impulse' ...



The 'tip impulse' ...



John

 

[rstl99]

Impressive video analysis John! Whatever this escapement is, it certainly is interesting, and intriguing! Bravo, Herr Albrecht.

 

[Dr. Jon]

I used an oscilloscope to examine the ticking.

Here are the tick elements.



The large burst are the escape action on the roller. I can't make sense of the smaller bursts, I had though they were the escape tooth catching in the vceter of the roller but they are not in that sequence. It may be as simple as interference with another sound source, The ticks are about 260 millesconds apart but between internet timing and recording the time scAle can be very distorted,

Here is a closer look at a tick. Note the time scale change. This looks to me the unlock on the left, impulse about 5 mi;;esconds later and lock about another 5 milliseconds later.

 

[Kinpol]

So, could we name this escapement as "Albrecht escapement" ?

 

[John Matthews]

Kinpol

I understand that the said Albrecht was active at the beginning of the C19th. The date for the virgule escapement ~1767 described by Lepaute and then developed by Lepine ~1780. I have also read that the double virgule proceeded it and was a development from the cylinder, attributed to Carron. Others, such as Graham or Robert, will probably have greater knowledge at their fingertips than me. However, I suspect in the late C18th early C19th there were talented watch makers, particularly in Europe, who were trying designs based upon those of the cylinder and virgule. Perhaps Albrecht was on of those watch makers. I have no knowledge of him, Graham, Robert, Enrico or Jon, may have more they can add.

John

 

[gmorse]

Hi Jon,

I can't make sense of the smaller bursts, I had though they were the escape tooth catching in the vceter of the roller but they are not in that sequence. It may be as simple as interference with another sound source,

I think you're probably right that they're spurious external noises, (there's quite a lot going on in the background of that video after all), although I often see similar artefacts in traces from verges, some of which I suspect are due to various wear points contributing their voices. The sequence of unlock, impulse, drop has to be the same as for any escapement, but the contributions and volume of the three components still aren't clear with this one. The considerations in the virgule of excessive wear and the problem of maintaining adequate lubrication are likely to apply to this escapement as well.

Regards,

Graham

 

[eri231]

unfortunately I have not found anything about it.only this escapement designed by Jean Guerin Paris, used by watchmaker Paliard of Besancon in 1780.

regards enrico

 

[rstl99]

I wrote about Caron's son's ca. 1753 double virgule escapement in NAWCC Bulletin in 2019 - you can find the articles here if that interests you (Part 2 in particular):
André-Charles Caron – Article – Time Tales – A la recherche du temps

Many escapements were developed by creative (and sometimes ambitious) watchmakers in mid-late 18th Century, in an attempt to make a name for themselves and render the watch more and more precise. After all, watches back then (and some clocks) were the "high-tech" personal items of the day (as smartphones and cars are today), and makers were competing with each other to develop the "next best new thing" to impress Science Academies and ultimately wealthy customers. Most of those exotic escapements were very short lived. The double-virgule in particular, must have been fiendishly difficult for a worker to make using the tools of the day, so impractical to manufacture in great numbers, and necessitated frequent maintenance. It's no wonder the cylinder, then the lever escapements, were to dominate the market, especially when mass-manufacturing techniques and machines were developed to produce them. They were "good enough" for most customers. But that didn't prevent creative watchmakers (like Herr Albrecht?) from trying their hand at something a little more challenging in decades that followed, which makes things interesting as this thread demonstrates.

Robert