Wm Webster lace-edge centre seconds cylinder 1760s - what's missing ?

[Andrew Wilde]

I've been looking for a good representative example of "lace edging" and this arrived recently. The lace edging strongly indicates an early 1760's date (movement and inner gilt case only, so no hallmarks to confirm). It's by William Webster II, rather than his father who in the early 1700s was a journeyman for Tompion, of Exchange Alley. Cylinder escapement, centre seconds, with a start/stop arm that operates on the base of the cylinder on the balance staff. As can be seen from the pillar plate pictures, the mechanism for operating the start/stop arm is missing - all that remains are two screws still holding the remains of this mechanism, either side of the arbor on which the start/stop arm is mounted. There is a slot in the rim of the inner case bowl where the operating lever would have protruded.
What I need help with is a description, or hopefully a picture, of what is missing from the motion work. The 6 spoke centre wheel under the steel bar is rotating once per minute. The solid wheel underneath appears not to be rotating, and has a smaller toothed wheel above it that doesn't connect with anything, so I'm thinking something is missing.
If anyone has a dial plate picture of a similar movement, or a diagram, or in fact anything that can help me understand what is missing, I'd be grateful.

 

[gmorse]

Hi Andy,

It appears to be the George Graham pattern where the seconds wheel is driven by an extra pinion on the escape arbor. I hope these pictures help. Yours appears to be missing the hour wheel. The seconds hand sits between the hour and minute hands.




The balance brake lever fits on that square and the pointed tip is held in one of two positions by the notch on the end of the spring. I assume that the two screws would have held a bridge to keep it firmly on the square, which isn't the case with my example, which is attached by a shoulder screw.

Regards,

Graham

 

[gmorse]

Hi Andy,

I'd like to see the dial if you get a chance, I think these centre seconds cylinders have the most beautiful dial and hands of any 18th century watch, they were always pretty exclusive and expensive, usually in gold pair cases. It should have the original Graham banking on the cylinder by the look of it; a very high quality piece of work.

Regards,

Graham

 

[novicetimekeeper]

I like lace edging, but so often is is worn and incomplete. That does seem to be a very good example.

 

[gmorse]

Hi Andy,

The solid wheel underneath appears not to be rotating, and has a smaller toothed wheel above it that doesn't connect with anything, so I'm thinking something is missing.

That's the minute wheel, are you sure it isn't rotating, because the cannon pinion is there on the centre arbor, so it should be.

Regards,

Graham

 

[John Matthews]

Andy - a very nice example.

I have one very similar from the same period, but lacking the lovely lace edging. I don't suppose the cap is stamped so ...



The missing balance brake mechanism which Graham has described has been broken away, it should be as in the second photograph ...



John

EDIT: just checked Loomes. William Webster II said to have been located at Change Alley, William Webster I at Exchange Alley. Now these may be the same alley, but I am assuming Loomes is recording how their watches were signed. The cock foot shape together with the lace edge of your example, all points to 1760s and therefore after the death of Webster I in 1734. I have a photograph of a Webster I verge which is signed Exchange Alley. Loomes may be in error with respect to the address signature, but it would be nice to see further examples. I think you are right with the date.

 

[Andrew Wilde]

Thanks to all for the replies.

Graham, thanks for those pictures - when you see it complete it's all rather obvious, but I'd not seen the motion work on one of these before. The balance brake lever explanation and picture too. The end of the squared arbor locates into a hole in the dial mounting plate (the brass edge I think some call it) so is held firmly at both ends. You're right about the minute wheel - it is rotating ! Not sure what you mean by the "Graham banking on the cylinder" but if you point me to an explanation I will confirm. Have added an image of the dial below - it is in poor condition but I think original.

John, thank you too for the pictures showing what that broken-off bracket would have looked like. There is no stamp inside the cover.
It is obviously not Webster I given the edging. Brittens has Webster II at both Change Alley and Exchange Alley; surely they are the same place with the name being misread or spelt in some source used to compile the locations.

Novicetimekeeper, I was pleased to find an example without damage and with the pattern used on the cock foot and regulator plate as well as the cock table. That was the reason for buying it and the interesting stuff going on between the plates, and under the dial, is a bonus.

And should have said something about the size, it's a fairly small movement - 33.5mm across the pillar plate.

Thanks again ... Andy

 

[gmorse]

Hi Andy,

Not sure what you mean by the "Graham banking on the cylinder" but if you point me to an explanation I will confirm.

The banking is accomplished by the radial pin in the lower part of the cylinder and a corresponding pin in the potence throat. These were often replaced with a plain cylinder and the banking converted in later repairs, involving cutting back the rim of the cock table and inserting a pin in the balance rim, but that clearly hasn't happened to yours, with that intact lace edge.

I'm not sure that the dial is original from the 1760s, although it does have 5-minute numerals; the example with Roman numerals in my earlier picture dates from the 1780s.

I'm not sure what the purpose of that bracket under the balance brake lever is; I had thought it might be a detent, but there's the notched spring for that.

Regards,

Graham

 

[Andrew Wilde]

Hi Graham - to confirm, the base of the cylinder does indeed have the banking pin, although I don't see anything on the potence that it would "bank" against. Maybe I'd have to disassemble it to find that, which I'm not going to be doing in the short term. My best attempt at a picture below.
Regarding the bracket under the balance brake lever, missing on mine but shown clearly in John's picture - it has a raised section at the midpoint and looks as though it is simply providing support for the lever and keeping it off the plate. Maybe a bit elaborate for that but I can't see any other explanation.
... Andy

 

[John Matthews]

My best attempt at a picture below.

You 'best' attempt is excellent!

John

 

[Andrew Wilde]

Thanks John. Getting a phone camera to autofocus on the cylinder and pin was a bit hit & miss !
I was just looking again at the balance brake mechanism picture that you posted back up the thread. Is there a cutaway at the centre point of that steel bridge under the lever, i.e. a gap between the pillar plate and the bridge ? Possibly a bit daft of me, but I was wondering if perhaps the bridge should be above the lever rather than underneath. It would make more sense then as a securing device for the lever, and also bounding the movement of the lever, but this only works if that gap exists.

 

[gmorse]

Hi Andy,

...to confirm, the base of the cylinder does indeed have the banking pin, although I don't see anything on the potence that it would "bank" against. Maybe I'd have to disassemble it to find that, which I'm not going to be doing in the short term. My best attempt at a picture below.

That's a good picture, the pin is nicely in focus, not that easy to achieve.



This example from a Mudge & Dutton watch has the pin set in a recess and it's invisible until the movement is dismantled, so yours may be similar.

Regards,

Graham

 

[John Matthews]

I was just looking again at the balance brake mechanism picture that you posted back up the thread. Is there a cutaway at the centre point of that steel bridge under the lever, i.e. a gap between the pillar plate and the bridge ? Possibly a bit daft of me, but I was wondering if perhaps the bridge should be above the lever rather than underneath. It would make more sense then as a securing device for the lever, and also bounding the movement of the lever, but this only works if that gap exists.

Andy - movement is now assembled and working in fact I have it on the timer at the moment.

I don't have any further photographs under the dial - I posted further photographs here.

If you look at this comparison ...

you can see that the lever rests on a raised central portion of the lever, such that the lever is close to the top (when the dial is uppermost) of the square end of the shaft which controls the 'balance' brake shaft.


I believe the pointed end of the lever is stepped down to engage with the spring.

If the brass edge is original (I am not sure if it is), then the depth of the associated slot will give you the distance of the lever from the pillar plate.

The comparison photograph shows that my brake operates by applying pressure to the fourth wheel arbor, originally it would have been as yours and operate against the escape arbor.

Hope that helps

John

 

[Andrew Wilde]

Hi John, thanks for further description and pointers to the other pictures of the movement. Clearly my speculation that the bridge maybe should be above the lever rather than under it is wrong, but someone has to ask the stupid questions ;-)
Nonetheless, it does seem to be a rather elaborate means of getting the protruding end of the lever at the right height, which would seem to be sole purpose of the bridge - a raised section in the middle, necessitating a step down in the lever to align with the spring, and still nothing holding the lever in place on the squared arbor other than a friction fit.
Thanks again ... Andy