A prominent use of a hog's bristle

Rory McEvoy

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This treasure is from the collections of the National Watch and Clock Museum in Columbia PA. This has a single hog's bristle that is placed in the center of the dial and its natural elasticity helps regulate the vibrations of the balance wheel. Unusually, this watch has a single hand the travels around the outside edge of the dial.

The back of the movement is beautifully decorated with pierced and engraved silver that showcases the maker's signature.

Johann Sigmund Schloer would have made this sometime in the first half of the 1600s. We do not know a great deal about this maker and would welcome any extra info.

BS27_184 3.jpg BS27_184 4.jpg
 
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VinSer

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Really really amazing :eek:

According to the Abeler (Meister der Uhrmacherkunst, 2e auflage) Johann Sigmund Schloer was from Regensburg and obtained the citizenship on 22 February 1658. He was born in "Weickhersheimb.".

There is a pocket watch with his signature in the collection of the Louvre (see here) and another one square-shaped in the collection of the Ermitage.

Ciao
 

jboger

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In his Lives of the Artists, Vasari tells a story about Giotto. It seems one day Giotto was walking through a village with a friend when a pig suddenly came rushing down the street and knocked him over. His friend asked if he should have the pig killed. Giotto replied, "No, no! His bristles are used to make my brushes!" So whether an early timepiece or a Renaissance masterpiece, three cheers for the pig and its bristles.
 

Bernhard J.

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From the first time, long ago, reading about these early "springs", I wondered whether there are specifications to be met by the pig and/or the bristles. There should be a significant difference in time keeping, depending on the bristle used?
 
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SKennedy

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I will admit that my knowledge of very early pieces is quite limited and so perhaps this is obvious to those in the know but...
It looks as though the bristle would have originally been mounted in a small square piece through that hole just under the XII. And so perhaps the piece/slide it is now stuck in to carried curb pins in those two holes which it would bear against at the limits of the balance arc.

Is the numbered disc on the back on the barrel arbor and so also a graduated means of adjusting the timekeeping by altering the set up of the spring?
 

Rory McEvoy

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Thanks Seth,
I like your suggestion. In its current form, the SS FF marks make little sense whereas a stud and sliding curb would work. The chapter around the barrel arbor does indicate degree of set up of the main spring. The indicator disc is missing and there's a worm gear behind the dial to apply the set up.
 

LloydB

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From the first time, long ago, reading about these early "springs", I wondered whether there are specifications to be met by the pig and/or the bristles. There should be a significant difference in time keeping, depending on the bristle used?
Bristles of this kind were used in early studies of
the skin senses (Ernst Weber, If memory serves).

In Weber's laboratory, the bristles were calibrated
by gently lowering each one vertically, 'til it would
'just' start to bend, on the pan of a sensitive scale.

They were inexpensive, spring-like, and easily-replaced.
 
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gmorse

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Hi Bernhard,
There should be a significant difference in time keeping, depending on the bristle used?
I must admit that I've never had the privilege of handling one of these, but most of the pictures of movements fitted with bristles appear to show that they functioned as resilient bankings, providing some return of energy as the balance bounced off them.

This example is rather different, because the bristle is in (relatively) positive engagement with the balance all the time, so it functions as a balance spring would. Wonder what the Young's Modulus of a pig's bristle is? (First catch your pig . . .)

Regards,

Graham
 

DeanT

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Hog's bristle regulation...one of my favourite topics!

Here's a photo of a table clock dated 1551. You can see the hog's bristle lever is able to be moved adjusting the point of contact with the balance wheel and therefore adjust the degree to which the bristle slows the balance. The degree of movement is measured against a scale. This is a pretty standard setup for 16thC clocks.



Hans_Stein_Meissel_Urmacher_zu_Prach_Domini_1551_Jar_(12).jpg
 

Victor Perez

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It is a really interesting watch. The dial is clearly designed to stand out the bristle. I wonder if its maker was experimenting by using the bristle as a balance spring. Are there any other clocks with that feature?

In some way it reminds me off the typical Renaissance clocks converted to pendulum with the pendulum in front of the dial. Was there a purely technical reason or they wanted to show the pendulum?

Anyway, I think this watch and its maker deserves further research.
 

Rory McEvoy

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It is a really interesting watch. The dial is clearly designed to stand out the bristle. I wonder if its maker was experimenting by using the bristle as a balance spring. Are there any other clocks with that feature?

In some way it reminds me off the typical Renaissance clocks converted to pendulum with the pendulum in front of the dial. Was there a purely technical reason or they wanted to show the pendulum?

Anyway, I think this watch and its maker deserves further research.
I agree, more research is needed. The few watches by this maker that I have found online are all quirky and quite eye-catching. This example from the Budapest Museum of Applied Arts has a great dial with calendar and moon phase.
 
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Bernhard J.

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Hi Graham,

This might be, but I would not be sure. On the other hand, the cutout looks to me as if it had been made at some later juncture and not really with topmost skill.

Best regards, Bernhard

BS27_184 3.jpg
 

jboger

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Bernhard, Graham:

Speculation on my part, but could the S and F refer to the strength or stiffness of the bristle, and thus mean S(anft) and F(ast)?

John
 

gmorse

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Hi Bernhard,
On the other hand, the cutout looks to me as if it had been made at some later juncture and not really with topmost skill.
I agree, that cut-out is a rough piece of work compared to the rest of the dial.

Perhaps whoever did it wasn't standing on anyone but rather looking over their shoulder?

Regards,

Graham
 
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Bernhard J.

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Bernhard, Graham:

Speculation on my part, but could the S and F refer to the strength or stiffness of the bristle, and thus mean S(anft) and F(ast)?

John
Hi John,

Not really ;). The opposite of "sanft" would be "rauh", "steif", "hart", but nothing with a "F" springs to my mind in this context. "Fest" perhaps, but this does not really fit the purpose of indication.

Cheers, Bernhard
 

jboger

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Bernhard:

I agree; it was just a thought. For the F I meant F(asst), with a "scharfes ess." So soft and firm. I don't think it makes sense either. Just a thought.
 
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VinSer

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... I though not, so are those markings a later addition? ...
There is also a regulator on the back.

So maybe the SS FF have another meaning ... no idea which one however :rolleyes:

Rory McEvoy : would it be possible to see a photo from the side of the movement?

Ciao
 

DeanT

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Hi Graham,

This might be, but I would not be sure. On the other hand, the cutout looks to me as if it had been made at some later juncture and not really with topmost skill.

Best regards, Bernhard

View attachment 724247
I think the entire mock pendulum aperture might be added. Looks like they hammered to edges to remove the engraved pattern.
 

VinSer

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Well seems that this time is my turn make to present a different hypothesis ... please let me know where I go wrong :)

The hypothesis is that the watch was badly restaured and that the hog bristle in that position is just creative restauring ... please wait with shooting

Without any previous knowledge when you look at the back of the watch movement, the movement is clearly inverted like in all watches with a mock pendulum on the dial. Also the numbered regulator must be able to act on the oscillation of the balance
BS27_184 4.jpg

Now, if we accept that the cut in the dial is a later addition, when you look at the dial there is no cut for the mock pendulum. But the drawing on the dial, the S S F F, appears to somehow imitate the writing on the back of a pendulum in a clock.
BS27_184 3.jpg

So my idea is that from the square hole was coming out an oscillating axis connected to the balance, on which a small mock pendulum was hanging; and there would have been curb pins to limit the run of the pendulum while being carried.

I have recently seen a much later, double dial french watch with such a mock pendulum; unfortunately I cannot find an image back.

Unfortunately the mock pendulum got lost, and the restaurer went creative ....

And then maybe I am completely wrong o_O

Ciao
 

gmorse

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Hi Luigi,
Also the numbered regulator must be able to act on the oscillation of the balance
Surely the regulator on pre-balance-spring watches like this didn't act directly on the balance, but controlled the tensioning of the mainspring, since that was the only way to alter the balance amplitude on a verge escapement. The balance wheel didn't have a natural frequency of its own without a spring.

Regards,

Graham
 
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DeanT

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Here's a watch from the British Museum with stackfreed to regulate the power of the mainspring and hog's bristle to dampen the oscillation of the balance.

 

gmorse

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Hi Dean,

Yes, the stackfreed was the alternative to the fusee for levelling the mainspring power curve, and the bristle(s) provided a sort of banking for the balance with some degree of momentum return when the balance bounced off them. They had to use some method of regulation since the stackfreed didn't provide any. This is probably why bristles don't seem to appear on watches with tangent screw and wheel regulation for the mainspring tension. Of course, this all changed around 1675, although the introduction of the balance spring didn't alter the fact that the rate of a verge, (being frictional rest), was still dominated by the power of the mainspring.

Regards,

Graham
 

VinSer

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Hi Luigi,


Surely the regulator on pre-balance-spring watches like this didn't act directly on the balance, but controlled the tensioning of the mainspring, since that was the only way to alter the balance amplitude on a verge escapement. The balance wheel didn't have a natural frequency of its own without a spring.

Regards,

Graham
You're absolutely right Graham.

Explained myself badly. Sorry
 

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