Blog: watch casesCopyright © David Boettcher 2006 - 2017 all rights reserved.
I make additions and corrections to this web site frequently, but because they are buried somewhere on one of the pages the changes are not very noticeable, so I decided to create this blog section to highlight new material. Here below you will find part of one of the pages that I have either changed or added to significantly.
This blog entry is part of my page about Watch Cases and Crowns
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Watch cases with two backs, or double bottoms
Double Case Back
One of the questions I am occasionally asked is "Why does the case have two 'backs'?". This is where a case has a hinged back that opens to reveal an inner back or cover, sometimes called a "cuvette", which is itself can be also hinged and opened to reveal the movement, or fixed to the band or middle part of the case in a double bottomed dome or Consular case.
This case design goes back to watches that were wound from the back, and some set from the back, with a key. Each time the watch needed to be wound or have the time set, the back was opened and a key with a hollow square end was applied to a square end on either the mainspring barrel arbor and turned to wind the mainspring, or to a square on a friction post that ran through the centre arbor and carried the minute hand and was turned to set the hands. If there were no protection for the movement, then a clumsy person could accidentally press the key into the watch mechanism and damage it.
In the earliest watches the movement was set into a case or "box" that had a hole in the back for the winding key. Sometimes this hole was covered by a little shutter to prevent dust entering, which was pushed aside to allow winding. This was not an entirely satisfactory arrangement, and watches usually had a second out case to protect the inner case. This arrangement was called a "pair case". The inner case of a pair case has a hole for the key to pass through to wind the spring, and the outer case then covers this hole.
The style conscious French nobility were never particularly fond of the bulky pair case, and the fashion that began in France around 1775 for close fitting waistcoats resulted in them abandoning it altogether. Jean Antoine Lépine fitted his watches with single cases with no hole in the back. The watch was wound through the dial, which spoiled its appearance and exposed the enamel to damage by the key of a clumsy owner.
To avoid the need for a winding hole in the dial, Lépine designed a case with a middle part, called the "band", to which the movement was fixed. A bezel carrying the crystal was fixed to the front of the band, and to the back were hinged two covers, an outer and inner. The outer cover is usually called the bottom or back, the second the inner cover or cuvette. The cuvette had one or two holes for the key, one offset from the centre for winding the mainspring, a second in the centre if the hands were set from the back.
Lépine invented hand setting from the back of the watch, boring the centre arbor so that a centre post that carried the minute hand could be passed through it, driven by friction between the two. The cannon pinion is mounted on the centre post. When the hands were set from the back there was no need for the front bezel to open and it was made to simply snap on, doing away with the need for a hinge at the front for the bezel. The movement was fixed to the band, eliminating the hinge for the movement to be swung out from the front of the case.
The case invented by Lépine, with the movement fixed to the band, snap on front bezel and two hinged backs, is sometimes attributed to Breguet, who later used the same design. Breguet usually made the inner cuvette of gilt copper or brass, and only made it of gold in watches of his top quality, ‘ouvrage premiere classe’. It thus became the standard practice in France to make the cuvette of base metal, except in the best quality work.
In English watches the inner cover, which was called the dome, was regarded as part of the watch case by the assay office, whether it was fixed to the band or jointed (hinged) to it in a Lépine style case. Because of this the dome had to be made of the same standard of metal as the rest of the case, e.g. 18 carat gold or sterling silver, or none of the case would be hallmarked by the assay office.
Like Breguet, Swiss makers did not regard the inner cuvette as part of the case, after all it was only there as a barrier to prevent a clumsy owner damaging his watch and was not seen when the back was closed, so they allowed it to be made of base metal. This was often plated with gold or silver to tone with the rest of the case, but marked "metal" or "cuivre" (copper) so that it could not be not mistaken for precious metal.
In later movements that were wound and set by the crown, the holes in the cuvette for the key were not needed, but it was retained for better quality watches. This may have been partly because of tradition, a sign of quality workmanship not found in cheaper watches, and it might give better protection against the ingress of dust than a single case back.
Watch cases: consular, double bottom, and dome
The definition of what constitutes a "consular" watch case is not clearly laid down in any reference that I have found. The name consular is sometimes used for the cases of English lever watches that have a jointed (hinged) bezel and back with a second, fixed, inner back called a "dome". I believe that this is incorrect.
In "The artistry of the English Watch", Cedric Jagger says The consular case - which is said, traditionally, to be associated with Napoleon's appointment as First Consul, even if the dates do not actually match up, - seems first to have been introduced by the precision watchmakers in c1775. Essentially, it is a single case with a double back, the outer of which is opened for access to the winding and hand setting squares, while the movement hinges out from the front." The government of France was called Consulate after the fall of the Directory in 1799 until the start of the Napoleonic Empire in 1804. Executive power was vested in three consuls. At first these were equal in authority, but Napoleon quickly consolidated power in himself as "First Consul".
This description of a single case with a double back would seem to apply to the cases of English lever watches, and several sources point in the same direction. Both Britten and de Carle imply that the terms consular and double bottom are synonymous, as does Terence Camerer Cuss in the glossary to "The English Watch: 1585 — 1970".
However, I noted that David Penney described on his web site that the case of Pennington watch No. 5443 has an "18ct gold case of true consular form, the band and both covers all pivoted on the same joint". David told me that in his view the distinctive feature of a consular case is that the front bezel and the case back are connected to the middle part of the case by a single "joint" (the casemaker's term for a hinge). The knuckles soldered to the bezel and case back, and the tubes or "charnières" soldered to the case middle part sit alongside each other and are all connected by a single pin.
After David explained this to me I went through Terence Camerer Cuss's book again and I noted that all the cases that are described as consular are in the chapter 1775 to 1825 and have the single joint feature, whereas later cases with separate joints for the back and bezel are called simply "cases". This confirmed to me that David's description of the single joint as the principal distinguishing feature of a consular case must be correct, although this doesn't appear in any book that I have seen.
The use of a single joint to hold the back and bezel to the middle part of a consular case is quite distinct from the later cases used for English lever watches that have separate joints for the back and bezel. I don't have any watches with consular cases but examples can be found on David's web site at David Penney's Antique Watch Store.
The consular case appears to be the first evolution of the pair case. The glass of a consular case is mounted to the bezel of the outer case, rather than a bezel on the inner case of a pair case watch. The bezel of the the inner case was discarded. The remaining half of the knuckles of what had previously been the joint between the bezel and the band and back of the inner case of a pair case watch were integrated into the joint of the outer case. The movement remained hinged at 12 to the vestigial inner case, which was now the case middle part with a fixed inner back.
French watches were sometimes wound through a hole in the dial and the hands set by turning them with a key on a square boss of the minute hand or centre arbor, so there was no need for the owner to access the back of the movement, so their cases had a single back or bottom fixed to the middle part of the case. Putting the winding hole through the dial was rather unsightly and often resulted in the enamel of the dial being damaged by the key. However, having only a single bottom meant that the case was as slim as it could be, which the current French fashion of the time for tight fitting waistcoats preferred. There doesn't appear to be a well defined name for this style of case, but Jean-Antoine Lépine of Paris was the pioneer of slim watches at the time. Open faced watches are generally known as "Lépine" watches, perhaps the design with a single bottom was the definitive version.
English watches usually wound from the back and had an enamel dial that was unmarred by a key hole, although they were generally set from the front by a key applied directly to the square boss of the minute hand.
Winding from the back necessitated a hole in the case for the key which needed to be covered to prevent dust getting in when it was not being used. This was the reason for the original pair case. The inner case of the pair had the hole, which was covered between windings by the outer case. Pair cases were not well sealed. The inner case carried the bezel and glass, the front opening in the outer case was open. This meant that dust and fluff could find its way into the outer case and between the two cases round to the winding hole. Nevertheless, pair cases continued to be made, mainly for watches with verge escapements, into the late nineteenth century.
When the English lever watch was developed around 1820 a better case design was also adopted. Like the earlier consular case, an outer bottom or back was hinged and when opened revealed an inner cover, called in English watches the "dome", which was fixed in place to the band or middle part of the case. The dome has either a single hole for winding, or two holes if both winding and hand-setting are from the rear. The glass is held in a bezel, and the outer back and bezel are attached to the middle part of the case by joints.
Unlike the consular case, the joints for the back and bezel are separate and located at different positions around the case middle part. This made them simpler, with fewer knuckles, which allowed them to be made smaller and less obvious. It would have been easier to make these simpler joints, but a challenge to solder all the charnières to the middle part of the case at the same time. This was probably the reason why they were in separate locations around the case middle part, so that they could be soldered in two separate heatings.
The movement is attached to the middle part of the case by a hinge at 12 o'clock. If it is to be examined or regulated the movement is swung out from the front of the case by first opening the bezel and then releasing a catch which holds the movement in place. The bezel is usually hinged at the side around 9 o'clock. The catch is below the six o'clock position on the dial, with the movement hinge at 12 o'clock. To fully remove the movement from the case, the hinge pin is pushed out. The practice of hinging the movement to the case continued in some high class English watches until about 1870.
The name of this style of case does not seem to be well defined. When I first bought an English lever watch I was told that it was a consular case, but thanks to David Penney I now realise that this is not the correct name. In his book "Watch and Clock Making", David Glasgow calls them "double bottom cases" and says that their cost was part of the reason for the decline of English watchmaking. However, I have also seen them called "dome" cases in nineteenth century sources. The term double bottom is rather generic and could apply to cases with a jointed inner back, whereas dome refers to the specific fixed inner back used in English lever watches, which seems to be preferable.
The first photograph shows an English lever watch. The front bezel with the crystal has been opened and the movement swung out of the case on a hinge located at 12 o'clock below the pendant. The small projection from the edge of the movement that I have ringed in red is the catch that normally holds the movement in place when the bezel is opened to set the hands, you press it with a finger nail to release the movement so that it can be swung out.
The outer back or case bottom is also open, showing part of the hallmarks for sterling silver. Inside the case you can see the dome, also hallmarked, that is fixed to the middle part of the case. In this watch the dome has a single hole for winding, which is isn't visible in the photograph.
In English watches, if the case is gold or silver the dome must be made of the same metal, because if it was not, none of the case would be hallmarked. English assay offices would refuse to hallmark an item that was not all of one standard of metal.
The second photograph shows the dust cap that covers the movement. The curved blue steel spring engages with two pillars on the movement (in the picture one of these is missing) to hold the dust cap in place. To release the dust cap you slide the blue steel spring round a little, as shown in the picture, and then the dust cap will lift off.
Copyright © David Boettcher 2006 - 2017 all rights reserved. This page updated January 2016. W3CMVS.