Thomas Earnshaw Original Lever? Or a conversion? How do you tell?

aucaj

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How do tell if a lever escapement is original or a later conversion? What are the indicators that a watch has been converted?

I don't see any unused pivot holes. Do cylinders 'cleanly' convert to levers by simply adding additional pivot holes?

Any information would be greatly appreciated.

This particular watch dates from around 1800. I assume that Earnshaw made escapements of all types: chronometer, verge, cylinder, and lever?

Thank you,
Chris

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remo87

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I guess the conversion from cylinder to lever escapement should leave visible traces, so if you can't see any proof of later ingerention, maybe the movement is original?
 

Dr. Jon

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David Penney's rule is that if it is before 1820 it was converted. I am not sure it is correct for this but is how I would bet. Earnshaw made all the other escapement in use around then.

A few aspects make me suspect that it is a conversion. It may have been an Earnshaw detent. The regulation scale is the one used for his sugar tong versions but the top plate seems to have been cut down removing part of fast end of the scale. The removed area is where the detent would have been secured, removing the place where large holes for the screws.

I am sure the top plate has been cut down but I am not completely sure it was detent. The sugar tong compensated detent watches I have seen in books are all over sprung. I suggest it was not a verge because it would have had a Tompion regulator. If converted from that, the scale would be complete.

This leaves the possibility that it was a cylinder or a duplex.

I am leaning towards a detent, since that is the best explanation of the cut upper plate.

The regulator is very badly shaped in that it cannot go the full range of the scale. The large screws securing ther pivoting axis of the regulator also look wrong. Teh earnshaw regulators he used are very well designed and graceful, compared to this one.

The lever shapes change a lot from 1800 and you may get an idea of the conversion date from details of the lever.

If it is an early Earnshaw lever, it's very rare and first I have seen.
 

Bernhard J.

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I am wondering a little bit (aside the cut regulator scale), I would have expected the Earnshaw signature on the upper plate, not on the barrel bridge. The latter had in most cases "London" engraved. But no rule without exception.
 

aucaj

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If it helps.... As point of comparison, here is another Earnshaw cylinder escapement that is close in serial number. You'll notice this one is Earnshaw's typical unadorned style with no engravings.

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aucaj

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This leaves the possibility that it was a cylinder or a duplex.

I am leaning towards a detent, since that is the best explanation of the cut upper plate.
Thank you for the detailed evaluation.
If it was converted, I would lean toward a duplex as the original escapement. Earnshaw detents all had two serial numbers. This watch only has the ‘common’ serial number. There is a 2017 paper by A D Stewart that provides some analysis on his serial number system and production.

Would a duplex accommodate the pivot hole pattern?

It is strange that the regulator scale goes to the edge. On a conversion, why bother with cutting down plate?

Regards,
Chris
 

John Matthews

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The cap maker's initials [IE] are commonly found on Barwise and Brockbanks capped movements ~1800-10, which given the relationship with the latter makes sense. I would expect that the cap was made at the same time as the original frame, if it fits as well to the back plate as it does to the cock table, I doubt if the plate has been cut back. I have seen other movements where the graduation of the scale appears to be truncated, with no evidence that the plate has been modified.

The question I have is what is the nature of the lever and roller. I think David's view relates to early single rollers - if they are earlier that 1820 inspect for evidence of conversion. I think the earliest verified single roller is 1818 and like a number of examples found its way to Ireland.

John
 

aucaj

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The question I have is what is the nature of the lever and roller. I think David's view relates to early single rollers - if they are earlier that 1820 inspect for evidence of conversion.

John
What is the best way to get a photo of the lever and roller? Should I remove the balance? Or should I do a complete disassembly?

Do you need any other photos?

Thanks,
Chris
 

Dr. Jon

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I am not fully convinced it was a detent but the single number does not refute this. The three known early Earnshaw's have single numbers.

The regulation scale seems original since it seems to have been partially cut off and this was on;y used on the sugar tong detents.

A lot of his early watches have very elaborate balance cocks.
 
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gmorse

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Hi Chris,

A lot of conversions and updatings involved re-gilding one or both of the plates, as well as alterations to the potence, so I think you're going to need a complete dismantling to look at all the evidence.

I've serviced a verge by him, case hallmarked 1825 and with a serial number in the 2900s. It was finely engraved and it did have a Tompion regulator.

Regards,

Graham
 
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SKennedy

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I think there is a hole that has been plugged between the current escape wheel pivot hole and the screw head holding the regulator arm in position. This could have been the position of the original escape wheel hole/plug for duplex/cylinder.
 
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gmorse

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Hi Chris,

When holes are plugged as part of conversions, it's often very hard to detect from the top of the plate, (the gilding covers things up), but clearer from the underside, but in this instance it seems very clear that something has changed. The pivot holes for the escape wheel in cylinders and duplexes were often set in plugs with blind holes, presumably to give better control over endshakes and allow for some adjustment as things wore.

Regards,

Graham
 
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aucaj

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I appreciate the assistance from everyone. When I bought it I had my suspicions when I saw the lever escapement. I can see now that is certainly a conversion, but I am glad to have it. Thank you for your comments.
 
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Dr. Jon

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I am coming to believe this was originally a detent watch. The British Museum catalog show two similar watches and also that I was wrong about the top plate being cut down.

If you can find the catalog these are catalogue number s 59, 61 and 62 all date to about 1800.

The balance cock is very much like the one in the Wright watch, which is also undersprung. If so your movement may be from the 1780's. About 100 of these had a punched legend identifying it as being made under the "Wright patent". If not under the balance cock this is punched inside the upper plate.

This is described in A. Randall 'AN EARLY POCKET CHRONOMETER BY THOMAS EARNSHAW, signed ROBERT TOMLIN' Antiquarian Horology,Vol 14 No 8 p611, 1984.

If your watch has this mark it is very significant and its conversion is a major loss to horology, but probably very valuable even as it is.
 
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Dr. Jon

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The article I referenced, and Graham corrected, shows the punch mark which is on another Earnshaw watch, signed by Tomlin.

A bit wide of the topic but of possible interest is that Tomlin signed the watch as "Watchmaker to the King" Tomlin seems to have left no other watches with his signature, raising the question of how he could use the title.

One possibility is that he did watchmaking for King George II who was very enthusiastic about watches. The recent Andrew Roberts bio states the during his period of mental illness he spent hours dis-assembling and re-assembling watches in his collection. Perhaps Tomlin assisted him in this and was truly a watchmaker to the king.
 

zedric

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The article I referenced, and Graham corrected, shows the punch mark which is on another Earnshaw watch, signed by Tomlin.

A bit wide of the topic but of possible interest is that Tomlin signed the watch as "Watchmaker to the King" Tomlin seems to have left no other watches with his signature, raising the question of how he could use the title.

One possibility is that he did watchmaking for King George II who was very enthusiastic about watches. The recent Andrew Roberts bio states the during his period of mental illness he spent hours dis-assembling and re-assembling watches in his collection. Perhaps Tomlin assisted him in this and was truly a watchmaker to the king.
When George II came to the throne he appointed Thomas Cartwright as watchmaker to the King. When Thomas dies, he appointed Benjamin Grey, which rules out Tomlin
 

Dr. Jon

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To date only one watch signed by Tomlin is known. My suggestion is that he used the title in another sense, of actually working with the King . He may had the watch made for his personal use. He is known only for this single watch.
 

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