Monday, 28 March 2016

An unusual watch by Errington with some interesting patents.

Click on the picture for a larger view.
This watch by C.H. Errington of Coventry was made in 1895 shortly before the business was acquired by Williams, it incorporates two Errington patents:

One was for a mechanism to let down the mainspring using the steel screw head visible bottom centre of the picture, this moved a cam which withdrew the "click" (ratchet) allowing the mainspring to be let down in a controlled fashion using the crown before removing the movement from the case.

This was a useful feature as normal methods could be rather hit and miss with the potential to cause damage, at least to the inner end of the spring, if let down too quickly. This set up was retained on many Errington and later Williamson movements for ten of fifteen years by which time the movement was no longer in [volume?] production.

A second example from 1895, this one with 11 Jewels
and for W.E. Weeks of Ryde.
The second patent was for the unusual position of the regulator curb pins protruding through the balance cock, this worked well but gave no significant advantage and would have been difficult to use with a Breguet hairspring and so, probably to avoid having two types of balance cock it was discontinued after a very short time. This is only the second I have seen and a few years ago when I showed the first of these to the Coventry Watch Museum they had not seen one either.

However in this example [update Jan 2017: And two other examples found since], the design led to an error. For a balance in this position the hairspring leaves the balance cock termination in an anti-clockwise direction and would be terminated on the right hand side of the cock looking at it as in the picture to the right. It would then move through the regulator curb pins which would be suspended off of the regulator towards the top of this picture.

Because the curb pins are under the balance cock this hairspring has to be terminated on the left of the cock passing under it. This probably mislead whoever put on the F[ast] and S[low] markings because they are the wrong way round as if the hairspring was moving off clockwise. So if this watch runs fast you have to move the index to F, lengthening the hairspring, rather then towards S as would normally be the case.
C.H. Errington of Coventry for A Faller of London,
Sterling Silver, 1895.

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