Watch Cases and Crowns

Copyright © David Boettcher 2005 - 2023 all rights reserved.

This page is about the manufacture, design and features of watch cases, and the crowns used for winding and hand setting.

Making Watch Cases

Making watch cases was one of the most difficult tasks to mechanise or automate. The development of automatic machinery in the nineteenth century meant that watch movement parts could be made by mass production methods, but case making remained an almost entirely manual craft skill.

This was principally because watch cases were usually made from silver or gold, and the amount of metal used to make the case had to be kept to a minimum. It would have been possible to machine a watch case from a solid block of silver or gold, but the cost of the raw material and the amount of waste that would need to gathered and recycled made this impossible due to the large financial outlay that would have been required.

The trade of watch case making began in the medieval period as an offshoot of gold and silver smithing, but quickly developed its own specialities and working methods. Philip Priestley identified signatures of 31 watch box and watch case makers on the 1697 Oath of Allegiance to William III, indicating that the separate trade of watchcase making was firmly established by then.

Gold and silver items must be hallmarked before being put on sale. An item cannot be accepted at a British assay office for hallmarking unless it carries a sponsor's mark which shows under whose responsibility it is submitted. In watch cases, the sponsor's mark identifies either the company that ordered the case to be made, or the company that made it. Watch case makers were businesses that employed a number a number of specialised craftsmen. The person who entered the sponsor's mark was the owner or a principal of the business. Whether they had any role in actually making watch cases is usually not known.

By the 19th century, watch cases were made in dedicated workshops containing the tools and machines required; lathes, draw benches, rounds and weights, and hearths for annealing the work and heating the soldering irons. Although steam power was available, and was used in some of the larger watchmaking factories, English gold and silver watch cases were almost all made in small workshops without power. Electricity was not available, so lighting was by gas lamps and power was provided by human muscles. A notable exception to this rule was the Dennison Watch Case Company.

The manually (foot) powered “pole lathes” used for turning operations would be familiar to any ancient Egyptian who happened to stop by. A flexible pole is fixed to the floor near the head of the lathe and a rope fastened to its top is wrapped around a pulley behind the chuck, with its lower end fastened to a foot pedal. When the foot pedal is pressed down and the rope drawn downwards, the work spins in one direction and then, when the pedal is released, it spins the other way as the bow pulls the rope upwards. The graver is used to make a cut as the pedal is pushed down and withdrawn when it is released.

The efficient production of watch cases was due to the work being divided into a number of specialist areas, the principal ones being:

• Case Maker, who formed, soldered and turned the main parts of the case
• Joint Maker, who made the joints (hinges) of the case
• Pendant Maker, who made the pendant that carries the bow
• Bow Maker, who made the bow and bow screw
• Boxer-In or Springer, who made and fitted the springs that open the case
• Engine Turner, who engraved the geometrical patterns using a rose engine lathe
• Polisher, who polished the case, and rectified the marks left by hallmarking

It might be noted that both pendant and bow makers were separate trades. In part this can be explained by the pendant being made as a casting, which required metal to be melted and poured into a mould; a process that would be unwelcome in the case maker's workshop. But another reason is that the bow and the pendant were the parts of the case that wore out soonest so there was a demand for these parts from the watch repair trade. A striking illustration of this is that from 30 November 1895 to 1 October 1896, the Birmingham Assay Office hallmarked 3,467 dozen silver cases and 17,331 dozen silver pendants.

Watch Cases were fabricated from sheet and bar material, which were formed into shapes, turned to the required size and cross-section and then soldered together. At least three grades of solder with different melting points were used so that successive solderings can be performed without the previous ones melting. There are about 50 solderings required in making a hunter case.

The hinges on watch cases are called “joints”, and making them was a highly skilled craft. To make the knuckles, tubes were formed from sheet, rolled and then passed through successively smaller holes in a draw-plate on a draw bench. Grooves for the joint were filed into the parts to be jointed, e.g. the middle part of the case and the back, and small sections of tube to form the knuckles soldered into each groove. Once the knuckles are soldered into place there is no possibility of altering their position, so it has to be right first time.

The joint pin is steel, and may be made shorter than the joint so that the ends can be plugged with the same metal as the case. If the pin is to be removed, the plugs must first be removed by, eg, digging them out with a graver. By convention, the pin is inserted from the right when the middle part of the case is away from the viewer, so should be pushed out from the left. The same applies to the joint that holds the movement to the case in a bolt and joint fitting.

There is a short video on YouTube of watch cases being made by Martin Matthews. There is also a short video about engine turning. Full length versions of both of these videos can be purchased from Martin Matthews Watchcase Maker. Martin, who died aged 77 years on 31 January 2013, was the fourth and last generation of watch case makers in his family. Although Martin made complete cases from start to finish, that would not have been a competitive way of working in the nineteenth century and his cases could have been expensive compared to those made by the typical watch case workshop of the time, where teams of workers each performed their own specialist aspect of the work.

Today, watch cases are pressed from stainless steel by powerful hydraulic machines. Because the raw material for each case costs only a few pence, economy in its use and reduction of waste is of no concern. One of the first, if not the first, companies to make watch cases in this way in the late 1920s was Taubert & Fils, who took over the Borgel case making business in 1924.

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Onion and Pumpkin Crowns

The round knob that sticks out from the top or side of the case and is used to wind the spring and set the hands is called the “couronne” in Swiss/French, which is crown in English.

On the type of old watches that I am interested in from the time of the Great War, crowns were usually one of two styles, onion or pumpkin. One often sees old watches with their crowns described as onion or pumpkin that look like nothing of the sort, which is rather confusing, so here are pictures of two crowns with my take on the terminology.

It is very simple really; does the crown look more like an onion, or more like a pumpkin?

The one at the top is an onion crown. You can see how its spherical shape with the vertical grooves to grip looks like an onion. This crown is on a Borgel cased wristwatch, the shape of the crown is necessary because of the design of the stem of a Borgel watch which required a significant stem tube projecting from the case.

The onion form is the older and sits neatly on the pendants of key wound pocket watches. Wristwatches don't usually have noticeable pendants, but one is necessary on a Borgel case to give space to accommodate a helical coiled spring.

The one below is a pumpkin crown. It is similar to the onion crown but more flattened, like the shape of a pumpkin.

The pumpkin form looks better at the side of an ordinary wristwatch case, the stem entering through a simple hole in the side of the case.

English watchmakers and repairers sometimes use the term “button” for this item. But since English watchmakers persisted with the fusee, which made keyless winding virtually impossible, they have little claim to name the part that operates the keyless mechanism. I don't like the term button, it is usually used in English for something sewn on to a garment to fasten it or something you press, e.g. to summon a lift. For watches I prefer the term crown.

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Savonnette and Lépine

Watches are traditionally divided into two broad categories: savonnette or Lépine, which in English are called hunter or open face. In old British catalogues, open face watches were sometimes referred to as crystal watches.

The terms savonnette or Lépine are used for a type of case and also the layout of a movement.

The distinction doesn't really apply to key wound and set movements, which can be put into a case in any orientation, provided that the dial is in the correct orientation for the case. But when stem wound and set keyless movements came along, their layout had to be made different depending on what type of case they were to be used with.

For keyless pocket or fob watches this was fairly straight forward, a savonnette case had a savonnette movement; a Lépine case had a Lépine movement. But when the wristwatch came along, this worked best with a savonnette movement in a Lépine case, which caused, and still causes, no end of confusion!

The basic rules about cases were:

• Savonnette (hunter) watch cases have a metal lid to protect the crystal over the dial. Keyless savonnette (hunter) movements and dials are laid out so that the pendant and crown are at three o'clock and the small seconds at 6 o'clock. When the movement is put into the case, the hinge for the lid of the case is at 9 o'clock.
• Lépine (open face) watches have no lid. Keyless Lépine movements and dials are laid out so that the pendant and crown are at 12 o'clock and the small seconds is at 6 o'clock.

This neat division lasted for centuries until the wristwatch came along. The fundamental objective of the wristwatch was to be able to read the time while leaving the hands free to do other things; the left hand holding the reins of a horse, or a rung on a trench ladder preparatory to going “over the top”, while the right hand holds a sword or revolver. This required an open face watch.

An open face Lépine watch has the crown in wrong position, at 12 o'clock where one lug for a wrist strap needs to be attached. A savonnette movement has the right layout, but opening the lid to read the time requires using the right hand and defeats the purpose.

The key to the successful wristwatch was the paradoxical use of a savonnette movement in an open face Lépine case, which has caused confusion about the use of the two terms ever since.

Sometimes open face pocket watches are seen with the crown at 3 o'clock and small seconds at 6 o'clock, which means that a savonnette layout movement has been put into an open face Lépine pocket or fob watch case. These are usually American made pocket watches, where they were called “side winders”. Why this was done I have no idea, there is no technical reason for or against it, it is just a question of style and convention.

Savonnette (Hunter) Watches

Savonnette or hunter watches have a hinged metal lid that closes over the front to protect the crystal. When the lid is closed the shape of he watch case resembles that of a small round cake of soap with slightly domed top and bottom, called in French a “savonnette”, hence the name. The English name arose because fox hunting men found it convenient to be able to open their watch and read the time with one hand, while holding the reins of their “hunter” (horse) in the other hand.

A savonnette or hunter watch, or watch case, sometimes called a “full hunter”, has a metal lid that completely covers the dial so that the time cannot be read without opening it. They are the most robust design of watch, but visually unattractive and a nuisance to use.

The watch in the image here is a demi-savonnette or half hunter, which means that it has a small round window in the middle of the lid so that the time can be read without opening the lid. These are sometimes called “Napoleons” because there is a story that the Emperor got so frustrated with having to open the lid of his hunter that he took a knife and made a circular cut out in the lid. They are easier to read than a watch with a full hunter lid, but the small window makes reading more difficult and reduces the accuracy to which the time can easily be read – the small seconds is not even visible.

From this watch you can see the savonnette or hunter layout with the 12 at the top, the hinge for the lid at 9 o'clock and the crown at 3 o'clock. There is a small seconds dial at 6 o'clock, but this cannot be seen with the lid closed.

Lépine (Open Face) Watches

The Lépine watch was invented in the eighteenth century by Jean Antoine Lépine who radically redesigned the standard watch movement of the time to make it much thinner. Because of Lépine's role in creating the modern design of watch movement, at various times his name has been used in to name different aspects of the design. See my page about Jean Antoine Lépine for more details about this important but little known maker.

Lépine made movements thinner by moving the balance down from above the top plate into the same plane as the rest of the wheels, pivoted in the bottom plate. The top pivots of the balance and train wheels were pivoted in cocks or bridges in place of a single top plate. Lépine created this design to make watches thinner, and this style of movement was known as the Lépine calibre.

Watches could also be made thinner by not having a lid or cover over the crystal, a design called "open faced". Naturally, in his desire to create the thinnest possible watches, Lépine mostly made open faced watches and, in time, Lépine was taken to mean any open faced watch, as opposed to a savonnette or hunter watch.

Open face Lépine watches usually have their small seconds at 6 o'clock as this one. There is no technical reason for this, it just seems to “look” right. It does mean that the layout of Lépine movements is different from that of savonnette movements, so that watch manufacturers had to make two different movements. These usually used identical components, the only difference between the two is that layouts of the bottom and top plates or bridges are different.

Wristwatches

When wristwatches were created, it was obvious that the 12 o'clock should be at the top when viewed on the wrist, where the upper part of the strap would be attached, and that it would be most convenient if the crown was at the 3 o'clock position and the small seconds at 6 o'clock. This meant using a savonnette movement. But the principal reason for wearing a wristwatch was to make it easy to read the time, and if the watch case was fitted with a lid, it either required the use of the other hand on the other wrist to open the lid, or if a demi hunter lid was fitted, the accuracy of reading was reduced.

It was abundantly clear right from the outset that to be most convenient to use, a wristwatch had to be open face. The key to the successful wristwatch was therefore to fit a savonnette layout movement into a case without a lid, an open face Lépine case.

Ergonomics

The layouts of movements, which gives different locations of the small seconds and pendant, which in stem wound watches carries the crown, differs between savonnette and Lépine movements for ergonomic reasons.

Savonnette watches usually have a button on the top of the stem to release the catch which holds the lid closed, and it is convenient to operate this button with the thumb, the watch being held in the palm of the hand. The lid then opens towards the fingers. Because of this, savonnette pocket watches have the dial arranged so that the pendant, the tube projecting from the case by which the watch can be suspended, is at 3 o'clock and the hinge of the lid opposite this at 9 o'clock. The small seconds display is at 6 o'clock.

Open face pocket watches are usually made so that the pendant is next to the 12 o'clock position on the dial. If a savonnette movement was used, the small seconds display would be at 9 o'clock, which somehow instinctively looks odd. So for open face pocket watches the movement was rearranged to put the arbor of the fourth wheel in line with the projected axis of the stem. This meant that with the crown at 12 o'clock, the small seconds display was at 6 o'clock. Because of its use in open face watches, which came to be called Lépine watches, this movement layout has itself come to be be called Lépine, although it was not much used by Lépine himself.

Distinguishing Savonnette and Lépine

The figure here shows how to distinguish between savonnette and Lépine movements. The movements are shown from the top, as if looking into the back of a watch, and the stems are at the top. This is the standard way that movements of any layout are illustrated in catalogues and movement identification books, and it makes it much easier to recognise movements if they are presented in this way. The red 12s show where the 12 would appear on the dial; they are reversed because the dials are on the opposite side of the movements in these images.

• If the balance is off to one side (it doesn't matter which side) from a line projected from the stem, it is a Lépine movement. The fourth wheel is directly on a line projected from the stem.
• If the balance on the opposite side of the movement to the stem, (it doesn't matter exactly where) it is a savonnette movement. The fourth wheel on a line is at 90° from a line projected from the stem.

The critical item is, of course, the location of the fourth wheel whose arbor carries the seconds hand, which determines where the small seconds will appear on the dial, but it is much easier at a quick glance to locate the balance.

Distinguishing between savonnette and Lépine watches is, of course, simple. If the case has a lid, it's a savonnette or hunter; if it doesn't have a lid it's an open face Lépine. But what about an open face wristwatch with the crown at three and the small seconds at six; is it a Lépine or a savonnette? In fact it's neither; it's simply a wristwatch!

Lépine Meanings

There are several meanings for Lépine in watch terms:

1. A bridge or bar type movement with the balance in the same plane as the train wheels.
2. An open face watch.
3. A watch movement with the arbor of the fourth wheel in line with the projected axis of the stem.
4. A movement layout where the small seconds is at 6 o'clock and the pendant or crown is at 12.

When the wristwatch was created it was natural to arrange the dial with the 12 at the top and the crown at 3 o'clock for both convenience of access for winding and for attaching the strap. This of course is a savonnette layout. But giving a wristwatch a lid would have defeated one of the principal benefits of a wristwatch, that it was possible to look at the time without using both hands, so wristwatches were almost universally open face.

The key to the successful wristwatch was therefore the paradoxical use of a savonnette movement in a Lépine case.

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Converted Wristwatches

Copyright © David Boettcher 2005 - 2023 all rights reserved.

Sometimes it is written that the first men's wristwatches were converted pocket watches, sometimes called “transitional” wristwatches. This is not correct. Although it may seem logical to assume that the wristwatch started in this way, and then purpose made wristwatches came along as a later development, this is an assumption that is not based on any evidence and it is wrong.

There was nothing difficult about designing or making wristwatches. Ladies had been wearing watches on bracelets and as wristwatches for centuries, but before WW1 (1914-1918) only military men wore wristwatches. If a man wanted to have a wristwatch, he could just go into a shop and buy one, but very few did, due to fashion and prejudices. When men's wristwatches suddenly came into high demand during the war, there were not enough new wristwatches to fulfil the demand so sometimes ladies' fob watches were converted into men's wristwatches by attaching strap lugs. Ladies' fob watches were used for this because they were the perfect size; men's pocket watches were too large to make comfortable wristwatches.

Converted wristwatches were not transitional in any way because they did not precede purpose made wristwatches. It was a very simple idea to attach two wire lugs to a case to take a strap or a bracelet. Ladies' wristwatches with bracelets had been specially made for centuries, and had been available in high street shops since the late 1880s. The advertisement reproduced here by Le Roy et Fils, the Parisian jeweller with shops in London, dates from 1887 and shows a small fob watch mounted on a registered design of bangle. Notice that although this is an open face fob watch, the dial has been rotated so that the 12 o'clock is where it should be on a wristwatch and the crown is next to the three.

Although this is not exactly what we think of today as a ladies' wristwatch, Le Roy also had a large selection of bracelet watches from 10 to 100 guineas, many of which were shown in later advertisements and which were true wristwatches. It did not require an enormous leap of imagination, or a twenty or thirty year “transitional phase”, for someone to come up with the idea of attaching a leather strap instead of a bracelet.

Purpose made men's wristwatches also appeared much earlier than many people think, around 1900. After all, what is the difference between ladies' watches and men's watches? A man's watch is usually larger and plainer, more masculine, in appearance; hardly rocket science. The wearing of a wristwatch was a matter of taste and fashion. Even though every army office wore a wristwatch, there was no demand for wristwatches from civilian men, who generally didn't wear things around their wrists. Because of this there was no mass market for men's wristwatches until the Great War, when large numbers of men joined the armies of Europe. They saw officers routinely wearing wristwatches; a practice which the new recruits quickly took up.

So before the Great War there was also simply no need to convert pocket watches into unsatisfactory wristwatches. If a man wanted a wristwatch, he could just go out and buy one. And in fact, military officers did just that. Advertisements from the period mention that wristwatches were sold to automobilists, balloonists, horse riders, and to military men, who were the largest group of customers for them. The vast majority of civilian men didn't wear a wristwatch, because it simply wasn't seen as necessary or fashionable.

My earliest wristwatch with a verified date is an IWC Wristwatch that was made in 1906. A Calibre 64 savonnette (hunter) movement was put into a purpose made Lépine (open face) wristwatch case with fixed wire lugs, ordered from Borgel in Geneva in September that year. This IWC wristwatch, and many other wristwatches from the pre-war period that were clearly made for men, show that purpose made men's wristwatch cases were readily available in the early 1900s.

Converted Wristwatches Exist

There undoubtedly were conversions of pocket watches into wristwatches. These are often easy to spot because they were not done by a watch manufacturer, and were often done pretty badly. Conversion of a pocket or fob watch into a wristwatch by the simple method of attaching two wire lugs, as mockingly described by Jaquet and Chapuis in The “Invention” of the Wristwatch, does not make a satisfactory wristwatch and is not nearly as common, or as early in the history of the wristwatch, as people sometimes think.

When and why were fob watches converted into wristwatches? Before the Great War there was no need for such conversions, because ready made wristwatches were available to buy in the shops. If a man wanted a wristwatch, he could just go out and buy one, but civilian men didn't so there was very little demand. But during the Great War, the sudden demand from thousands of newly commissioned officers for wristwatches quickly bought up the existing stocks and exceeded watch manufacturer's production capability to make new ones. This is when and why fob watches were converted into wristwatches.

Because the watches converted into wristwatches that can be positively dated, e.g. from hallmarks, are from the period before the Great War, sometimes long before, the mistaken assumption has been made that they were converted before the war. But I have evidence that proves that this is not the case. The original pocket watches were, of course, made before the war, but their conversion to wristwatches was done during the war, because the supply of new men's wristwatches could not satisfy the sudden increase in demand brought about by the war.

The reality is that converted wristwatches did not precede purpose made wristwatches and there is no such thing as a “transitional” wristwatch. Fob watches were converted into wristwatches during the Great War when the supply of new wristwatches could not keep up with the sudden surge in demand for wristwatches from newly commissioned officers desperate to get to the front before the war was over.

Practicality of Conversion

Before getting into the evidence of what actually happened, let's look at how easy it is to convert a pocket or fob watch into a satisfactory wristwatch. I say a “satisfactory wristwatch” because I mean a wristwatch that customers would actually want to buy from a shop, to wear and show off to their friends, not something that looks like it has been hurriedly cobbled together out of whatever was available under trying circumstances and doesn't do the job very well.

Wristwatches don't usually have a lid as a hunter watch does, because that would defeat the point of strapping the watch to a wrist – which was to make it easy to access and read the time without using both hands. If a wristwatch has a hunter lid, both hands are needed to read the time, the left to bring the watch into view, the right to open the lid. For this reason the vast majority of wristwatches are open face.

Hunter wristwatches, and demi or half hunter wristwatches with a small window in the lid, are seen from the time of the Great War, obviously with the idea that the glass would be protected from knocks in the trenches, bullets and shrapnel. But these are few and far between, because they are awkward to read and quickly annoyed their users. Sometimes they are missing the hunter lid; I wonder how many were torn off by frustrated wearers?

If a pocket watch was to be converted into a wristwatch, then it would usually be an open face pocket watch. How easy was it to make one of these into a wristwatch?

Here is a picture of a small open face Borgel pocket watch that I have rotated to bring the crown to 3 o'clock as if it were a wristwatch. A couple of problems with this as a wristwatch are immediately apparent.

• The number 12 is next to the pendant and crown, which makes it difficult to read the time.
• The small seconds dial is opposite the crown, not the customary place for a wristwatch.
• The long pendant carries a bow to which a safety chain is usually attached.
• There is usually an engraved pattern on the back of the case (not shown).

Pocket watches converted to wristwatches usually show signs of all these problems. The 12 is often in the wrong place, or the dial feet have been cut off so that the dial can be rotated. The bow has been removed and the pendant and winding stem cut down, usually quite obviously. The position on the sub seconds display cannot be moved and would still appear at 9 o'clock, so often watches were chosen that have no seconds display. Nothing is done about the engraving on the back of the case, which is not a problem in itself but is a dead give away that the watch left the factory as a pocket watch.

It is in fact much more difficult to convert a pocket watch into a satisfactory wristwatch than it is to simply make a wristwatch in the first place.

Making Wristwatches

The reason that it is difficult to make a satisfactory wristwatch from a pocket watch, and the key to the successful wristwatch, was the paradoxical use of savonnette (hunter) movements in Lépine (open face) cases, which at the time was very unusual.

Savonnette (hunter) watch cases, such as the one on the right in the image, have a hinged metal lid (ringed red) to protect the crystal. Savonnette (hunter) movements and dials are laid out so that the crown is at three o'clock and the small seconds at 6 o'clock. The hinge for the hunter lid is at 9 o'clock.It is easy to see how adding lugs to the case would have the basic layout of a satisfactory wristwatch.

Lépine (open face or crystal) watches, such as the one on the left in the image, have no lid. Their movements and dials are laid out so that the crown is at 12 o'clock and the small seconds is at 6 o'clock. This design was created in the eighteenth century by Jean Antoine Lépine to make watches slimmer, but is also has the advantage that it is easy to see the dial and hands; there is no need to open a lid to read the time.

The principal reason for wearing a wristwatch was to make it easy to read the time. If the wristwatch had an open face, this could be done with minimum effort just by looking at the wrist, which could be done while holding things in both hands e.g. the reins of a horse in one hand and a revolver in the other. However, if the wristwatch was fitted with a hunter lid, both hands were needed to read the time; the wrist with the watch and the opposite hand have to be brought together to open the lid. If a demi hunter lid with a small window in the middle was fitted, the accuracy of reading was severely reduced. These practical considerations meant that an open face Lépine case was needed.

However, if a Lépine movement was used and the lugs were soldered onto the case so that the crown was on the side, where it was most convenient, the 12 would also be on the side, next to the crown, and the small seconds would be on the opposite side of the dial. This made it very awkward to read the time, and is the principal problem that most conversions suffer from. It was obvious that the 12 o'clock should really be at the top of the dial when viewed on the wrist, where the upper part of the strap would be attached. A movement that had exactly this layout, with the crown at the 3 o'clock position and the small seconds at 6 o'clock, already existed; a savonnette movement.

The key to the successful wristwatch was therefore to fit a savonnette movement into an open face Lépine case.

For more details about the difference between Lépine and savonnette movements and cases, see Savonnette vs. Lépine.

Instead of going to the unnecessary trouble of converting pocket watches, a manufacturer wishing to make wristwatches would take small savonnette movements that they were already making and put them into purpose made open face cases with short pendants and lugs for a strap and, hey presto, wristwatches! Was putting a savonnette movement into an open face case that had been purpose made with lugs to take a wrist strap and without a pendant and bow really a form of conversion? No, of course it wasn't.

This use of savonnette movements in open face cases, which for centuries had been called Lépine cases, gave rise to a new terminology. This is shown in the image here taken from an IWC catalogue of spares (fournitures) published in 1917. The calibre 63 on the left is described as a Lépine,naturally enough, but note that the calibre 64 on the right is described as a “savonnette et montres bracelet”, a “savonnette movement for hunter cases and for open face wristwatches.

The paradoxical combination of a savonnette (hunter) movements in Lépine (open face) cases is why early wristwatches have the number 12 picked out in colour. Because they were open face they looked at first glance like a Lépine watch adopted for wrist wear, but the savonnette movement meant that the 12 was in a different place to where it could be found on a normal Lépine watch and a red or blue 12 was used draw attention to this.

Evidence from the Great War

So when were the conversions of pocket watches into the converted wristwatches that one sees today actually carried out?

Available evidence indicates that these conversions were done during the early years of the Great War. Since the late nineteenth century an officer in the British Army had been expected to wear a wristwatch. During the Great War, as the army expanded, many new officers were commissioned, and each one used his outfit or kit allowance to purchase his kit for the front; uniform, sword, revolver, etc. - and a wristwatch.

At the start of the war there was such a demand from newly commissioned officers for wristwatches that the supply of new wristwatches couldn't keep up. At this time, fob watches were converted into wristwatches for officers determined to kit up and get to the front before the fighting was over, which in 1914 it was expected to be by Christmas.

I have the Longines trench watch shown in the image here. It's a nice size for a man's wristwatch, 35 millimetres across the silver Borgel screw case, not including the wire lugs or the crown, and the dial has the skeleton numerals and hands with radium luminous paint that were so necessary in a trench watch. The movement is a Longines calibre 13.67 Lépine with 18 jewels.

The Longines serial number of the watch is 2,241,923, which shows that the movement was made in 1909. The Borgel case has London Assay Office import hallmarks for sterling silver with the date letter “n” of 1908 to 1909 – remember that date letter punches were used over two calendar years. So the watch was made and cased in 1909.

However, it doesn't look like a Longines wristwatch that was made in 1909. For one thing, it has simple fixed wire lugs instead of the characteristic hinged “swinging” lugs that were usual for Longines wristwatches made at the time. Secondly, the dial has skeletonised numerals and hands with radium luminous paint. Luminous dials were not used when this watch was made in 1909. There is no seconds indication on the dial; Longines wristwatches made at the time usually had small seconds indications at 6 o'clock, so this is also odd.

The secret is revealed by Longines records, which record that this wristwatch was invoiced and sent to Baume & Co. in London on 12 March 1915. Why did this watch, which had been made in 1909, remain in Longines inventory at the factory in St. Imier until 1915, some six years later?

The answer lies in the sudden overwhelming demand for wristwatches from newly commissioned officers getting kitted out for the front in the Great War. The quotation from the Horological Journal of October 1916 shown in the image here confirms that so great was the demand for wristwatches that manufacturers were compelled to convert ladies' watches into military timepieces.

Because these conversions were done by watch manufacturers themselves, they were not the rough bodge of a conversion from a fob watch into a wristwatch that is often seen today and recognised as a conversion. Factory conversions are much harder, sometimes impossible, to recognise as such. The reason that ladies' watches were used was because their movements, at 12 or 13 lignes, were the right size to make men's wristwatches. Sometimes these movements hadn't even been cased, meaning that they were just bare movements, not watches for either sex. When uncased movements were put into wristwatch cases, that wasn't even a conversion; it was simply assembling a wristwatch.

These factory conversions were done properly, which meant not only adding strap lugs and removing the pendant from a Lépine open face fob watch but also, most importantly, replacing the dial with one in the correct orientation for a wristwatch, so that the 12 was in the right place at the top of the dial and the 3 next to the crown.

The principal feature of Longines No. 2,241,923 shown in the photograph that would have not been found on a Longines wristwatch made in 1909; the luminous dial and hands, show that this watch started life in 1909 as a small open face pendant or fob watch that was converted into a wristwatch, a trench watch with a luminous dial, at the Longines factory in 1915.

The Great War created a huge demand for wristwatches. Initially Longines was able to fill orders with purpose made wristwatches, but by 1915 demand was outstripping supply. Thirteen ligne open face fob watches were a suitable size for wristwatches, so fob watches like number 2,241,923 were drawn from stock and converted to wristwatches by removing the bow and cutting down the pendant, soldering wire lugs to the case and fitting a new luminous dial and hands.

Because the movement is a Lépine, the small seconds on the new dial would have been at 9 o’clock, so instead of putting a samll seconds dial at this unusual position, which would have looked a bit amateur, the arbor of the fourth wheel was shortened and the seconds indication omitted from the dial. This was not ideal, a small seconds indication was useful to reassure an officer that his trench watch was working when it could not be heard ticking due to the noise of gunfire, but needs must and the demand for wristwatches was great.

This watch is clear evidence that conversions of pocket watches into wristwatches took place during the Great War due to the sudden overwhelming demand by new officer's for trench watches, which demand was soon followed by newly enlisted men of other ranks. Many conversions were performed by jewellers and are easily spotted. This conversion was more competently done at the Longines factory and is not so easy to spot, but Longines archives are an invaluable record and show without doubt what actually happened.

Further proof of this is that many converted pocket watches bear British import hallmarks. Whatever the hallmark date, import hallmarks show that the watch was imported after 1 June 1907 when import hallmarking of watch cases began. But my 1906 IWC wristwatch, which has no hallmarks because it was imported in January 1907, shows that purpose made men's wristwatches were being made before these later imports were converted into wristwatches. Since purpose made wristwatches were available, why would anyone go to the trouble before the war of making an unsatisfactory wristwatch by adding strap lugs to a fob watch? Especially at a time when there was very little demand for men's wristwatches at all.

The evidence shows that wristwatches made from converted pocket watches did not precede purpose made wristwatches. Conversions of pocket watches into wristwatches were done during the Great War, when the supply of wristwatches could not keep up with the demands of newly commissioned officers urgently getting kitted out for the front.

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Watch Cases with Two Backs

One of the questions I am occasionally asked is "Why does the case have two backs?". This is where a case has a jointed (hinged) back that opens to reveal an inner back or cover, sometimes called a "cuvette", which is itself can be also be opened to reveal the movement.

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 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 outer 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.

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Pair Cases

Early pocket watches, particularly verge fusee watches, have “pair cases”; two completely separate cases, one inside the other. The inner case is sometimes called the box, after the continental practice of calling it a boîte, and the outer case is called the case.

The principal purpose of the outer case was simply to cover the hole in the box or inner case through which a key was inserted to wind the watch.

The box is a bowl shaped piece into which the movement is inserted and secured. The bezel that carries the crystal attached to the main part of the box by a joint (the case maker's term for a hinge).

The movement is secured into the box by “bolt and joint.” The joint is at 12 o'clock, the bolt is a spring loaded catch at 6 o'clock. When the bolt is pressed inwards towards the centre of the dial, the movement can be swung out of the front of the box on the joint.

The box has a hole in its back through which a key is inserted to wind the mainspring. The outer case is provided simply to cover up this hole at all other times. When the inner box and outer case were integrated into a single item, the term box was dropped and the whole thing was called a case. On the continent, watch cases were almost always called boxes (boîtes).

Sometimes a second outer case was provided, usually of a non-precious material such as leather. This was to protect the case, which was often richly engraved, chased or enamelled. The inner box was plain, because it was not seen except when the watch was being wound.

The image here shows an English pair cased watch with a verge fusee movement. The bezel of the box, top right, is wide open and the movement is shown partially swung out of the box on its joint. The bolt at 6 o'clock is just visible, as are the cut-outs for it in the rim of the box and bezel.

If you enlarge the image, you should be able to make out the cone shaped fusee between the plates of the movement, on the right behind a pillar. The wheel in the foreground with teeth pointing downwards is the contrate wheel, a sure sign of a verge movement.

The box has London Assay Office hallmarks for 1844 to 1845, the sponsor's mark is the initials JB over WW struck incuse without a surround. This mark was entered on 27 June 1834 by Josiah Barnett & William Walters in partnership at 15 Lower Charles Street, Northampton Square, Clerkenwell.

The outer case on the left is sterling silver and has the same London Assay Office hallmarks as the box, but there is no visible sponsor's mark. The semi-circular cut outs in the rims are for the pendant, which is attached to the inner case. The rusty iron strip is the spring for the catch that normally holds the case closed.

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Consular Cases

An English lever watch is often described as having a “consular” case. 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 frequently used for any case that has a jointed (hinged) bezel and jointed back, with a second fixed inner back with a hole through it for the winding key. I believe that this is incorrect and that the consular case is a particular version of a double-bottom case.

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 circa 1775. 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 swings out from the front." The government of France was called the 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 all equal in authority, but Napoleon quickly consolidated power in himself as “First Consul”.

Jagger's description of a single case with a double back, one that opens and one that is fixed in place with a hole or holes for the key, would 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” [emphasis added]. 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 what is otherwise called a hinge). The tubes or “charnières” of this joint, soldered to the bezel, case back and the case middle part, all 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, not consular cases. This confirmed to me that David's description of the single joint being 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. In a pair case watch, the movement is contained in an inner case that has a hole in the back for winding and a jointed bezel which carries the glass and is opened to set the hands. To prevent dust entering through the winding hole, the inner case is encased in an outer “pair case” which is jointed at the middle so that the watch can be removed for winding. The front of the pair case has no glass, it is just an open ring or bezel.

In a consular case the inner and outer cases of a pair case were combined into one. The bezel of the inner case was discarded and the glass was mounted in the bezel of the outer case. The charnières of what had previously been the joint between the band and the back of the inner case of a pair case watch were integrated into the joint of the outer case. The movement remained attached 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 in itself, and it 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.

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Double Bottom and Dome Cases

What is the difference between a double-bottom case and a dome case?

English watch cases with two backs - a jointed (hinged) outer back that can be opened and an inner back that is fixed to the middle part of the case and cannot be opened - are called double-bottom cases.

Although from the following it is clear that at least some parts of the English watch trade regarded a “dome case” as one with an outer and inner back which both open, the term “dome” was also used for the fixed inner bottom of an English double bottom case, which can be confusing.

In the Horological Journal of April 1894 are the questions for the 1893 City and Guilds Institute examinations in watch and clock making, to which Mr T D Wright of the BHI added such answers as appeared likely to satisfy the Examiner. One of Mr Wright's answers clarifies the difference between a double-bottom and a dome case.

Question 5. Distinguish between a “dome” case and a “double-bottom” case. For what kind of movement is each case respectively well suited ? And in what manner should either movement be attached to the case?

Mr Wright's specimen answer to question 5. A “dome” case has the inner bottom (in which the wind-up holes of a key-winding watch are made) opening on a joint in a similar manner to the outer bottom. A “double-bottom” case has the inner bottom made solid with the middle, or band, of the case. The double-bottom is suitable for a capped full-plate keywinder, while the dome case is well suited for a keyless watch. With the former, the movement is always attached by a bolt and joint, so that it may be opened by the wearer for regulating. With the latter, the attachment is by means of a pin and dog-screws. With a dome key-winder, a joint is generally used instead of dog-screws, because it makes the firmer fixing and there is no winding pinion in the way.

Mr Wright's answer needs a bit of unpicking.

The dome case he describes has two backs, both of which are jointed (hinged) to the middle part of the case and can be opened. If the watch is key wound, the inner back has a hole off centre for the key, and a second hole in the centre if it is key set from the back. These holes are covered when the outer back is closed. This type of case was typically used for Swiss watches, many of which were keyless and therefore have no holes in the inner case back. In this case, the inner back simply provides additional protection to the movement.

The notice here about Martin's dome case was published in 1875 and shows that, at the time, the case backs were called the inner and outer bottoms. The unusual feature of Martins design is that the inner back snaps inside the middle part of the case by its outer edge, instead of snapping over a raised ring on the middle part of the case as is usual. John Martin was a London watch case maker. He appears to have taken over the business at 48 Wynyatt Street Clerkenwell from James Martin, possibly his father, who first entered a sponsor's mark at the London Assay Office in 1822. In 1873 John Martin was awarded an honourable mention for very good specimens of case making by the council of the British Horological Institute.

The double-bottom case is a typical English case, with a jointed outer back that can be opened and an inner back that is fixed solidly to the middle part of the case. The inner back has a hole for key winding, and sometimes a second hole in the centre for hand setting, although many English watches are set from the front. This requires opening the bezel which carries the glass and applying the key to a square boss on the minute hand, with the chance of bending or pulling off the minute hand, or damaging the hands or the dial in the process.

The movement in a double-bottom case is attached to the case by bolt and joint. The bolt is the catch at 6 o'clock that can be released by a thumbnail to swing the movement out of the case on the joint located at 12 o'clock. The movement is detached from the case by pushing out the joint pin. The pin is usually tapered and will only come out one way, usually by pushing from left to right when facing the dial with the 12 at the top. Usually the pin pushes out quite easily; if it doesn't, try looking at the ends of the pin to see if it has been inserted incorrectly. A stiff piece of wire is usually sufficient to push the pin out; this can be mounted in a wooden handle and called a “joint pusher”.

The assertion that the joint makes a firmer fixing than case screws is a spurious attempt to make the English method of fixing movements to their cases sound superior to that of the Swiss method of using screws. In fact, many bare (uncased) English movements are seen where the joint, or the part of the bottom plate to which the joint is attached, are bent, because the movement was simply wrenched from the case by twisting the joint by hand. This is not possible when the movement is held into the case by screws. It is also easier to open the inner case back of a dome case to adjust the regulator than it is to open the bezel of a double bottom case, release the bolt, swing out the movement and remove the cap.

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English Lever Bolt and Joint Cases

English pocket watches are often wound from the back and the hands set from the front, by a key applied directly to the square boss of the centre arbor which carries the minute hand. Because there has to be a hole in the back of the case for the key to enter, English lever watches usually have “double bottom” cases.

Winding from the back necessitates a hole in the case for the key, which must be normally covered to prevent dust getting in. This was the reason for the original pair case where 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 movement was developed around 1820, a better design than the pair case was also adopted. Like the earlier consular case, an outer bottom or back was attached to the middle part of the case by a joint. When this outer back is opened, it reveals the inner cover which is fixed to the middle part of the case. This inner cover has either a single hole for winding, or two holes if both winding and hand-setting are from the rear. In this case, the central hole is the one for hand setting.

The glass that protects the dial is held in a metal ring called a bezel, which is also attached to the middle part of the case by a joint.

Unlike the consular case, the joints for the back and bezel of an English lever case are separate and located at different positions around the middle part of the case. This made them simpler to make, with fewer knuckles, which allowed the joints to be made smaller and less obvious.

Bolt and Joint

The movement is attached to the middle part of the case by a bolt (catch) at 6 o'clock, which is circled in red in the image here, and a joint (hinge) below the pendant at 12 o'clock.

If the movement 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 the bolt which holds the movement in place. The bezel is usually jointed to the middle part of the case at the side around 9 o'clock. To fully remove the movement from the case, the joint pin is pushed out, usually from left to right. This method of attaching the movement to the case continued in some high class English watches until about 1870.

When I first bought an English lever watch, I was told that this case 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. Glasgow uses the term dome for an inner cover that is jointed (hinged) to the case and can be opened. This usage can also be found in the Horological Journal, so it is evident that at the time they were made this style of English lever watch case was called double bottomed. Here the terms outer and inner case back are used for the two bottoms.

In the photograph, the outer case back is open, showing part of the hallmarks for sterling silver. The inside of the hallmarked inner case back, which is fixed to the middle part of the case, is also visible. In this key wound and set watch the inner case back has a single hole for winding, which is isn't visible in the photograph. The hands are set by opening the front bezel and applying the key to the square boss of the minute hand.

If a gold or silver watch case is to be hallmarked, the inner case back 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 and the inner case back, which was rigidly fixed to the middle part of the case, the case band, was regarded as an integral part of the case.

Opening an English Lever Case

To open the case of an English lever watch, start by opening the front bezel, the hinged metal ring at the front which carries the crystal. Once the bezel is open, set the hands to 12 o'clock so that they are well out of the way.

Next, look at the dial below six o'clock. You will see at the edge of the dial a small piece of steel that is normally covered by the bezel. This small projection from the edge of the movement that I have ringed in red is the bolt (catch) that normally holds the movement in place. It has a horizontal slot on its outer side for a finger nail.

Press the bolt towards the centre of the dial with a finger or thumb nail. Be careful not to slip and catch the seconds hand. A small movement of the bolt will release the movement so that it can be swung out of the case on the joint (hinge) located at 12 o'clock below the pendant.

To release the movement from the case completely, the pin of the joint is pushed out, usually from left to right.

This method of holding the movement in place is called “bolt and joint.”

Removing the Cap

The movement is covered by a gold plated metal cap. It might seem logical to call this a dust cap, but the proper term for it is simply the cap.

The curved blue steel strip engages with two pillars on the movement (in the picture the lower one of these is missing) to hold the cap in place. It is fixed to the cap by the central rivet, which allows the strip to slide.

To release the cap, slide the blue steel strip round in the direction shown by the red arrows and the cap will then lift off. There is a peg at the middle of the strip where the middle red arrow is in the image. Use a finger nail to press against this peg.

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Swing Ring Cases

The swing ring case was invented by Ezra Fitch in 1879 as part of the design of a waterproof case, see Fitch Swing Ring Case. Fitch's case had a carrier for the movement that was hinged to the case so that the movement could be swung out from the front and there was no need for a separate case back. This is the swing ring element. A screw down front bezel made the remaining front joint watertight. The entrance to the case for the stem was sealed by the simple expedient of a cap that completely enclosed the crown and stem and screwed down onto the end of the pendant.

The swing ring part of Fitch's design proved to be surprisingly long lasting. The image here is taken from Robert Pringle & Sons "Wilderness" catalogue for 1932. It is from a page marked "Special Dust and Waterproof Watches". The page includes Borgel, screw back and bezel and hermetic watches, and also a cushion shape watch by Helvetia with "a patent device for rendering the stem watertight".

The swing ring watch is also marked Helvetia on the dial and has a 15 jewel lever movement with shock absorber. However, there is absolutely no provision for sealing the slot in the case side that the stem drops in to, and because the case is a cushion shape the bezel snaps on. This watch has no waterproof features and should not have been on this page.

Watches with swing ring cases are sometimes called "semi-hermetic" because they often have a fluted screw down bezel and look superficially like some watches with waterproof cases such as the Borgel screw case or the Finger/Gruen Hermetic. But if they don't have any means of preventing water entering the case where the stem passes through they are not even remotely hermetic and should not be called such.

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Black Oxidised Steel Watch Cases

Watch cases were sometimes made from steel, This was cheaper than gold or silver, but prone to marking and rusting. To make the case more attractive and give it some protection against rusting it was hot chemically treated . The process turned the steel black and the cases were described in Swiss/French as "acier oxide", or oxidized steel. The oxidised finish was attractive and reasonably satisfactory in everyday use, but it was not very successful in preventing rust in damp conditions. When these cases are seen today the black surface layer has often worn thin or been removed by polishing, showing the silvery grey of the underlying steel.

Black oxidizing, or caustic black as the process is sometimes called, involves immersing steel parts in a caustic soda (sodium hydroxide [NaOH]) salt bath at about 140 degrees Centigrade (290 degrees Fahrenheit). The reaction between the iron in the steel and the hot oxide bath produces magnetite (Fe₃O₄), which forms an attractive and moderately corrosion resistant dark black finish on the surface. The parts are usually oiled or waxed after treatment to improve corrosion protection. Because of the temperature and the caustic materials involved, this is a dangerous process.

Some idea of the specialised nature of the process may be gained from the advertisement here by Jean Finger, a case maker of Longeau who later patented the hermetic watch case, or case within a case. This advertisement is from April 1894 and at the bottom says "Oxidages soignés de boites acier n'étant pas de ma fabrication", i.e. that the company will carry out oxide treatment on steel watch cases that are not of their own manufacture; they will treat watch cases for manufacturers who don't have the capability to do it themselves.

The second advertisement appeared in the 1901 Goldsmiths Company Watch and Clock Catalogue for a military pocket watch, The Company's Service Watch. It was described as “The most reliable timekeeper in the World for Gentlemen going on Active Service or for rough wear.” The UNSOLICITED TESTIMONIAL at the bottom of the advert, dated June 7th 1900, states Please put enclosed Watch in a plain Silver Case. The metal has, as you can see, rusted considerably, but I am not surprised, as I wore it continually in South Africa on my wrist for 3½ months. It kept most excellent time, and never failed me. Faithfully yours, Capt. North Staffs. Regt.

The Captain's watch was the version cased in an oxidised steel case shown in the middle picture. This made the watch, at two pounds ten shillings, considerably cheaper than one with a silver case, which the advert shows was priced at three pounds ten shillings, a considerable increase of one pound; 40% more. The 18 carat gold case was considerably more at twelve pounds, nearly five times as much as the one in the steel case. Which raises an interesting point; the same watch mechanism could be housed in either a steel, silver or gold case at the customers choice. As the mechanism was the same in each case, its cost must have been the same, and must have been part of the cost of the cheapest watch, the steel one, at two pounds ten shillings. The difference in cost of nearly ten pounds between a steel and 18 carat gold case watch was therefore entirely due to the extra cost of the gold case. A rough estimate might put the cost of the watch mechanism at two pounds and the steel case at 10 shillings, giving the price of the steel watch at two pounds ten shillings. Which would make the gold case, at ten pounds, twenty times as expensive as the steel case, and five times as expensive as the watch mechanism itself.

You will notice that the Captain says I wore it continually in South Africa on my wrist for 3½ months. This was during the Boer War in South Africa, and he had been wearing his watch in a leather wristlet, which you can read more about on my page The Evolution of the Wristwatch: Wristlets. During the same war a Borgel watch in an oxidised steel case spent several days in the Modder river.

A particularly attractive use of black oxide finish in combination with gold was used by François Borgel to create a case for an IWC pocket watch with a stunning dragon design which can be seen by following this link: Borgel black oxidised dragon case.

Gunmetal?

The same process is used by gunsmiths to produce an attractive cosmetic appearance and measure of corrosion resistance to firearms; because of this the finish is sometimes called "gunmetal". This is unfortunate because gunmetal is really a copper alloy similar to bronze that was used to make cannon before large steel forgings were possible.

When used in regards to watch cases, "gunmetal" doesn't refer to the type of metal used, which is steel, but only to the black, or sometimes dark blue, surface finish. In 2012 the Swiss watchmaker F.P. Journe presented in New York City an exhibition entitled "Steel time: The largest historic collection of gunmetal watches of the mid 19th century". I thought at the time, and I still think, that this is a very unfortunate use of the word gunmetal; collectors need to be aware of this usage but I hope they will avoid propagating it, or at least qualify it as "gunmetal finish".

Bluing

A similar process using a solution of potassium nitrate and sodium hydroxide heated to around 140°C produces a blue finish.

This is a different process to the blue produced by simply heating polished steel parts until a blue coloured oxide film appears, and both processes are different to the bluing produced by "Engineer's" or "Prussian" blue that is painted onto parts in the workshop so that they can be marked out prior to cutting and shaping.

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Niello or Nielled Silver

Niello is the name of a type of inlay technique where designs that have been punched or engraved into the surface of a metal object are filled with a black compound. It is an ancient technique, dating back to the Mediterranean bronze age and ancient Egyptian civilisations.

A compound of sulfides of silver, copper and lead is prepared by melting a mixture of silver, copper and lead and pouring the molten alloy into a crucible containing flowers of sulphur. Sal ammoniac (ammonium chloride) is added and the mixture pulverised. This is placed into depressions made in the surface of a metal object as a powder or paste, then the article is fired until the niello compound melts and bonds to it the surface of the object. When cool the surface is polished and the black filled areas contrast with the surrounding polished metal.

Huguenin Frères

One of the principal makers of niello silver items was Huguenin Frères in Le Locle, one of the principal watchmaking towns in the Swiss Jura mountains.

The company styled itself as “Huguenin Frères & C°, Fabrique Niel, Le Locle”. Beginning as makers of silver watch case, the company diversified into making other jewellery items such as badges and brooches. When stainless steel replaced silver in the 1930s for watch cases, manufacture of badges and medals became the company's principal activity.

The company still exists and their web site can be visited by clicking on this link: Huguenin Frères.

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Gold Plated Watch Cases

In the context of watch cases, ‘plated’ means that a core of cheap base metal is covered with a thin skin of a precious or expensive metal such as gold to give it the appearance of an item made of gold but at lower cost. Because the item is not made of solid gold it cannot be hallmarked. The are broadly two types of gold plating, mechanical and electrical.

Mechanical gold plating, called "gold-filled", "rolled gold" or "rolled gold plate" (RGP), is made by bonding thin layers or sheets of gold with heat and/or pressure onto a core of base metal such as brass. The thickness of the gold determines how long the item will last in normal use before the gold layer wears through and the base metal shows, which is often expressed in years. Sometimes a statement such as "Guaranteed not to wear through for X years" is made, where X is a number such as 10 or 20. Sometimes just the number of years such as "10 years" is stated.

Electroplating is where a base metal item is suspended in bath of solvent that contains salts of the required plating metal and an electrical current is passed through the solution, which causes the plating metal to be deposited onto the base item. Different colours of plating, e.g. rose gold, can be achieved by using the right plating solution. The layer of plating deposited can range in thickness from ½ micron (1 micron is 1 millionth of an metre; one thousandth of a millimetre or 0.00004 inches) upwards. The quantity of gold used on electroplated items is so small that it is essentially negligible and costs very little.

Electroplated gold items may have the initials GP or GEP. Gold is very soft and gold plate that is only ½ a micron thick will wear through very quickly. Better quality plating of between 1 to 20 microns will last longer, and heavy electroplating of around 100 micron thickness will last a lot longer. If you are buying an item that is plated and it means a lot to you or the person you are going to give it to, then find out about the quality and in particular the thickness of the layer of plating. However, any electroplated coat will wear through quite quickly, which is why no lifetime is quoted on such items.

Because plated cases are not solid gold they cannot be hallmarked.

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Chrome Plated Watch Cases

The first commercial process for chromium plating was developed in 1924 in America and chromium or chrome plate didn't come into use for watches until some time after then. The 1930s economic depression that followed the Wall Street crash of 1929 meant that manufacturers were looking for cheaper but still eye catching alternatives to gold and silver. Stainless steel was introduced in the 1930s for the same reason

Rolex were one of the first companies to use chromium plated watch cases; Hans Wilsdorf registered the name Snowite in Switzerland in February 1927 for watch cases made from chrome plated zinc alloy.