Hi Astral,
Thanks for posting these pictures, I know it can be a little scary opening up a watch like this if you've never done it before, but I hope you've found it worth doing!
The chain isn't missing, it's either just unhooked from the barrel or it may be broken. They're similar to bicycle chains but very tiny, with a hook at each end, and many were made in the 19th century by girls working in Christchurch in Dorset.
This will give you an idea of what your watch looks like when the top plate is removed. Although it's rather older than yours, (around 1720), it's essentially the same, the verge design didn't change very much for over 200 years.
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You can see the conical fusee and the fine chain which connects it to the barrel. When the spring is fully wound the chain is pulling on the smallest radius at the top of the fusee and as it runs down the radius gradually increases, the pull it exerts remains fairly constant, and in a verge this has a significant influence on the timekeeping. The last picture is the balance wheel with its spring and the two 'flags' on the staff; this is the oscillator which controls how fast the mainspring can drive the watch.
The interpretation of English hallmarks isn't always straightforward, especially if they're at all rubbed, as here, and practice and experience helps a lot. A legal set of marks consists of the Assay Office, the date letter, the purity mark and the maker's or sponsor's initials. Although there are several offices still in existence, (and several more which have now closed), the most likely marks to be found in a watch case are for London, (a leopard's head), Birmingham, (an anchor), and Chester, (a shield with a sword and three wheat sheaves; this office closed in 1962). The date letter changes every year, and each office has its own series, which before 1975 changed in different months in the various offices; London in May, Birmingham in July, and Chester sometimes in July and sometimes in August, (they changed over the years). A date letter could therefore apply to part of two calendar years before being rationalised in 1975. The purity mark for sterling silver, (92.5% pure), is a lion passant, and the maker's or sponsor's mark consists of the initials of their first and last names, which are kept in registers at the assay offices. If two makers with the same initials need to be registered at the same office at the same time, their marks must be distinctive in some way, either in their font or the surround in which they appear, or even in the presence of a full stop between the letters.
Although the signature is for Samuel Vale, you shouldn't think that he made the watch all by himself; he would have overseen a group of specialised craftspeople, each working on a specific part of the watch, some working exclusively for him and some providing a service externally. It's estimated that between 40 and 50 people were involved in the making of a single watch.
Regards,
Graham