VintageWatchstraps Logo

Vintage Watchstraps

Straps for Vintage Fixed Wire Lug Trench Watches or Officer's Wristwatches

The evolution of the waterproof watch

Copyright © David Boettcher 2005 - 2024 all rights reserved.

I have titled this page the "evolution" rather than "invention" of the waterproof watch because, like the wristwatch, the waterproof watch was not something that needed to be "invented" as such. When the watch itself was invented, it was obvious that the mechanism needed to be encased to be safely carried about, and it would have pretty soon become clear that protection from dust would be an advantage to preserve the oil and keep the watch running for longer periods between needing to be cleaned and re-oiled. And it would also quickly be obvious that protection from moisture would also be a good idea to prevent the mechanism from rusting. So gradually watch cases were improved to seal better against dust and moisture, and the fully waterproof watch eventually evolved.

This improvement was at first gradual as watches could only be afforded by the very wealthy, who did not care to get themselves or their watches wet, but as the watch became to be a necessity for the common man, particularly after the coming of the railways in the nineteenth century, the pace of innovation quickened. There was always a balance to be struck against the degree of protection afforded to the movement and the inconvenience caused to the wearer, so the evolution of the practical and yet fully waterproof watch took place over many years in a series of incremental steps.

For the purposes of this page I have adopted the use of the term waterproof as it was used at the time a watch was created, which generally meant it would withstand rain and splashing with water whilst hand washing. The requirements of recreational diving, or even swimming wearing a watch, were not considered until well into the twentieth century.

Water Resistance

The term “waterproof” is not used for watches today, recognising that such an absolute standard cannot be achieved. Instead it is replaced by “Water Resistant” along with a pressure rating in atmospheres and metres or feet of water, which gives an idea of just how water resistant the watch is. There are two international standards that regulate the testing of watches, ISO 22810:2010 Horology - Water-resistant watches, and ISO 6425:1996 Divers' watches.

The normal pressure of the atmosphere atmosphere at sea level is about 14½ pounds-force per square inch (psi) or 1 bar - a standard atmosphere is 1.01325 bar. This is equivalent to a column of mercury in a barometer of 29.92 inches or 33.9 feet of water, which is about 10.3 metres of water. So one bar pressure is equivalent to about 10 metres water gauge or depth under water.

A watch that is described as water resistant might be less waterproof than you might think. A watch rated at 3 atmospheres (3 atm) or 30 metres / 100 ft water depth might seem at first sight to be more than adequate for swimming or showering. After all, you are hardly likely to get 100 feet deep in a swimming pool! However, this rating is a static pressure that the watch was tested to when it was new. There are all sorts of reasons why a watch of this rating is not suitable for swimming, such as the pressure is increased by movement - diving into water, or the jet from a shower create a much higher dynamic pressure. And that pressure rating was recorded when it was new - over time the seals deteriorate and need to be renewed. Unless a watch has been tested for water resistance within the last year, you should assume that it is NOT water resistant. If it has been tested, the certificate will tell you its level of water resistance.

  1. Watches rated at 3 atmospheres / 30 metres are resistant to rain or splashes from hand washing, but are not suitable for swimming or wearing in the shower.
  2. A watch rated at 5 atmospheres / 50 metres will tolerate gentle showering, but not power showers or jumping or diving into water.
  3. For swimming, water resistance of at least 10 atmospheres / 100 metres is required.
  4. For sub-aqua, water resistance of at least 20 atmospheres / 200 metres is required.

Watches don't remain water resistant for ever. Before a watch described by the manufacturer as water resistant left the factory, it was tested and carried a time limited guarantee. When it was subsequently serviced at the specified interval, the water resistant seals should have been renewed and the water resistance tested and guaranteed again. A factory licensed watchmaker would do this, but they are expensive and people often shop around for a cheaper price.

Machines for testing water resistance are relatively expensive, and one of the easiest things to leave out that doesn't appear to affect the going of the watch is changing the seals. Both of these factors make the job cheaper, and the receipt usually has “water resistance not tested or guaranteed” stamped on it so there is no mistake. Such a watch must never be exposed to water, even when washing hands it should be taken off first.

Many years ago I entrusted a valuable watch of mine to a swanky jewellers in a nearby posh town, who described themselves as specialists in elite jewellery and prestige Swiss watches. They persuaded me that it was not necessary to send the watch to the manufacturer's service agent because their own service department could do it just as well, and more quickly and cheaply. They didn't change the case seals before testing the watch for water resistance, which it naturally failed and they noted on the invoice. But in the process water had got into the case and that evening I saw droplets of water condensing inside the glass. Even though I immediately took the back off and pulled the movement out, the dial, hands and movement were all ruined. They were replaced by the manufacturer's service agent, who also changed the case seals and guaranteed that the watch was waterproof. It was a very expensive lesson.

If you are concerned about the water resistance of your watch, a very simple test is to place an ice cube on the glass and, after a while, look for signs of condensation on the inside of the glass. A very small amount of condensation is acceptable, after all, all air contains some moisture in the form of humidity which will have been trapped inside the watch when it was closed up. But more than a small trace is a cause for concern and you should get it professionally checked.

The bottom line: water getting into a watch can be a disaster. The steel parts rust and the watch can quickly become unrepairable. Economy here can easily turn out to be false economy! If your watch is not highly water resistant, or you are not sure how water resistant it is, don't take chances, keep it dry. If you want to splash about in the shower, swimming pool, or in the sea, get a properly water resistant 100m+ watch, get it tested and the seals checked and replaced regularly, and then don't worry about it.

If you have any questions or comments, please don't hesitate to contact me via my Contact Me page.

The World's First Waterproof Watch

The earliest evidence which I have found of a truly waterproof watch is this report of a watch exhibited at the Great Exhibition in London in 1851. The watch by W. Pettit & Co. of 2 Crombie's Row, Commercial Road East, London was exhibited performing suspended in a glass globe filled with water and, according to the "Official Descriptive and Illustrated Catalogue of the Great Exhibition", surrounded with gold and silver fish.

The Illustrated London News, in a supplement actually printed at The Great Exhibition, stated "Messrs. Pettit and Trappett exhibit a silver watch, which is suspended in a globe filled with water. The object of the invention, the exhibitors say, is to secure the works from sea water, & c."

1851 Great Exhibition Waterproof Watch
Great Exhibition Official Catalogue 1851
1851 Great Exhibition Waterproof Watch
The Illustrated London News 1851

A watch exhibited at the Great Exhibition in London in 1851 performing suspended in a glass globe filled with water and surrounded with gold and silver fish must be the world's first waterproof watch, surely? It must have been quite a striking sight.

The 1851 "Great Exhibition of the Works of Industry of All Nations" was the first of the world's great international exhibitions of manufactured products. The brainchild of Henry Cole and Prince Albert, it was held in a purpose-built Crystal Palace in Hyde Park. The opening ceremony was attended by Queen Victoria and Prince Albert, and the exhibition was an enormous success. One third of the population of Britain visited the exhibition between 1 May and 11 October, and the surplus from ticket sales was used to found the Victoria and Albert Museum, the Science Museum and the Natural History Museum.

W Pettit watch
W Pettit watch

In the official catalogue of the exhibition Pettit & Co. are described as "Inventors" and it is stated that "The object of the invention is to secure the protection of time-keeping and other instruments from water, sea damp, rust &c." (emphasis added). The use of the terms "inventors" and "invention" made me wonder if this invention had been patented. However, the UK Intellectual Property Office have searched their records filed between 1820 to 1900 and found no trace of a such a patent.

The watch shown here is marked on the dial W. Pettit, Commercial Road East. It is Swiss made and has a fully jewelled right angle lever escapement and double bottom jointed silver case. Although competently made it is nothing special. Because the case is Swiss and was evidently imported before 1907 there are no British hallmarks to give a date. The bow has two Swiss standing bears, but the pendant and case have no Swiss hallmarks so it appears that the bow is a later replacement. This suggests that the watch pre-dates the introduction of Swiss hallmarking in 1880.

Both Pettit and Trappett sound like Swiss names to me, so it appears that Pettit was an importer of Swiss watches, and that Trappett, probably a fellow Swiss, approached him to get his invention manufactured.

vade mecum fishbowl
Rolex vade mecum fish bowl

And that, sadly, is all that I have been able to discover about the watch by W. Pettit & Co. and Mr. Trappett. There is no mention of this in the Horological Journal because the British Horological Institute was not formed until 1858, seven years after the Great Exhibition.

Many people think that Rolex introduced the first waterproof watch, or at least the first waterproof wristwatch. But in fact you will have to read a long way down this page past numerous waterproof watches and wristwatches before you come to the first waterproof Rolex watch, the Rolex Oyster. In the Rolex jubilee vade mecum, Hans Wilsdorf talks about the launch of the Rolex Oyster in 1927 and window displays they devised for retailers with an aquarium forming a centre piece - I wonder if he knew that he was following in the footsteps of Messrs. Pettit and Trappett and the method of display they chose for their waterproof watch that was made some 76 years earlier?

Back to the top of the page.

A L Dennison and Early Waterproof Watches

Aaron Dennison was an important pioneer in watchmaking by machinery; in fact it could be said that he was the most important pioneer, in that it was his ideas that started the mass production of watch movement parts by machinery in America, which had major knock-on effects on watchmaking in Switzerland and England. After initiating a revolution in watchmaking and other adventures, Dennison set up a company in Birmingham, England, to make watch cases, and many collectors will have watches with cases made by the Dennison watch case company.

There is more about the Dennison Watch Case Company on my page about A L Dennison.

There are stories that Aaron Dennison was involved in early waterproof watches and invented the screw down crown, but despite searching I have not found any evidence to support this and I believe that the story is apocryphal.

Dennison and the Screw Down Crown

Dennison 1871 patent story
Story from NAWCC web site about Dennison 1871 patent - original source unknown

Donald de Carle in Practical Watch Repairing, in the chapter on Water-Resistant Cases (on page 276 in my copy), says “There are three popular types of [water resistant] button and pendant. The screw button and pendant, originally invented by A. L Dennison as long ago as 1871, is used in various forms today ...”

I have seen another reference to this story in an excerpt from an American publication on the NAWCC web site as shown here. The NAWCC library have been unable to trace the publication in which this appears.

In The Principles of Waterproofing Watches Henry Fried says that Dennison encased watches in waterproof cases as far back as 1871, and that New York watch collector Louis Romaine has a Waltham watch with one of these cases. The problem with Fried's account is that he says that Romaine's watch has a screw cap, and he illustrates it with a figure from an American patent granted to Ezra Fitch. Fitch's patented design is different to a design patented by Dennison in 1872. In fact Romaine's Waltham watch was one of a number of similar watches with a case made in America to Fitch's patent. Dennison had absolutely nothing to do with it.

The use of a screw cap to enclose the crown and seal the gap where the stem enters the case is not really rocket science. It was used on “travellers'” or “explorers'” watches in the 1870s, such as those commissioned by the Royal Geographical Society. A cap over the crown was simple and effective, but not a very elegant solution to the problem. A much more effective solution was to use the crown itself as the cap, to arrange for the crown to screw down on the pendant or stem tube. A crown that screwed down onto the pendant was patented by Fitch in 1881, and this appears to have been the first true screw down crown.

The claim that Dennison invented the screw down crown is repeated in several places, so it might be thought that there may be some truth in it, but I have found no substantive evidence in its support. I have never seen a Dennison watch case from the nineteenth century with a screw cap over the crown or a screw down crown.

I think that this is just a tale that grew and changed in the telling and retelling, and that in fact Dennison did not invent the screw down crown.

Dennison's 1872 Patent

I asked the UK Intellectual Property Office in Cardiff to search for a Dennison patent of around 1871 and they came up with two; No. 356 dated 3rd February 1872 and No. 1113 dated 31st March 1874. These were the only two patents they could find attributed to Dennison around 1871.

Dennison patent 356
Dennison 1872 patent GB 356

On 3rd February 1872 Aaron Dennison of Handsworth, in the County of Stafford, Watch Manufacturer, deposited an application and preliminary specification for a patent for Improvements in Watches and Pocket Chronometers, which were said to consist of constructing the parts of watches and chronometers so that they are simplified and perfected, and the cases made air and water tight. On 29th July 1872 this application was approved and Dennison was granted British patent No. 356.

Dennison 1872 No 356
Dennison patent claims

To make the case air and water tight, in place of the normal hinged bezel, Dennison designed a bezel with an external screw thread which screwed into a thread in the opening at the front of the case, from inside the case. I have circled this in red on the left hand side of the picture. The bezel is item "b" with external screw thread "d". The bezel screws from inside the case into the thread in the front part of the case, part "e" in the diagram.

The back of the case "f" had an internal thread which screwed down onto a thread "g" formed on the middle part of the case. The small screw labelled g2 was there purely to give some grip for screwing and unscrewing the back. This must have been before Dennison conceived of using the peripheral "coin edge" milling seen on later Dennison screw cases, which is not surprising, the patent was written several years before he started his watch case factory.

The winding stem and push piece for engaging the hand setting mechanism were provided with packings of an unspecified nature to make them "air and water tight." Note that these were simple gland packings, there was no screw cap or crown mentioned and I am sure that the story that Dennison invented the screw down crown is wrong.

This case was designed before Dennison set up his watch case factory, but shows that he was thinking about watch cases as well as watch movements. The patent also covered a mechanism for winding and setting the watch via the crown, using a push piece to put the keyless work into the hand setting position. Winding and setting the hands was an important consideration for a sealed case, because it was common at the time for the case to be opened to perform these operations, but there is no suggestion that Dennison invented keyless winding and setting.

There is more about the Dennison Watch Case Company on my page about A L Dennison.

Back to the top of the page.

1878 Explorers' Watch
1878 Explorers' Watch
1878 Explorers' Watch
1878 Explorers' Watch

Explorers' Watches

In the latter part of the 19th century, the needs of explorers and travellers to lands with extreme, in particular humid or damp, climates give rise to a class of hermetically sealed watches now often called "explorers' watches", or sometimes "travellers' watches". These watches had their backs and bezels screwed onto the middle part of the case, sealed by leather gaskets set into grooves. A cap enclosing the crown was screwed onto a threaded end of the pendant to seal the gap where the stem enters the case, again with a leather washer for sealing. I have been unable to locate a patent or any documentation concerning the design of these watches.

Marine chronometers were not suitable for this type of work because the chronometer escapement is extremely fragile and not suitable for rough treatment. Explorers' watches used English lever escapements, which were capable of good timekeeping, not quite as good as a chronometer escapement, but much more robust.

The pictures here, by kind permission of Pieces of Time in Mayfair, London, are of one of these watches. The watch has a keyless fusee English lever movement with up / down indication on the dial. It is stem wound and key set, that is the crown is used only to wind the watch: to set the hands the back must be unscrewed and removed to gain access to a square boss on the central minute arbor. It was owned at one time by Vice Admiral A. W. Craig of the Royal Navy.

Although the stem wind and set mechanism, doing away completely with the need to use a separate key to wind a watch and set the hands, had been invented by Adrien Philippe of Patek Philippe in 1845, there was a reason for retaining key set for the hands of these watches. It was to avoid the time being re-set inadvertently. Watches like these and marine chronometers, which were used for determining longitude, were not adjusted to local time or to compensate for errors in time keeping. Before setting out they were carefully "rated" to determine their mean daily error.

In strictly horological terms, "rating" a chronometer means that prior to the instrument entering service, the average rate of gaining or losing per day is observed and recorded on a rating certificate which accompanies the instrument. This daily rate is used in the field to correct the time indicated by the instrument to get an accurate time reading. Even the best made chronometer with the finest temperature compensation etc. exhibits two types of error, (1) random and (2) consistent. The quality of design and manufacture of the instrument keeps the random errors small. In principle the consistent errors should be amenable to elimination by adjustment, but in practice it is not possible to make the adjustment so precisely that this error is completely eliminated, so the technique of rating is used. The rate will also change while the instrument is in service due to e.g. thickening of the oil, so on long expeditions the instrument's rate would be periodically checked against accurate time determined by astronomical observations.

The daily rate observed during rating was used during the expedition this was used to calculate the true time, by adding or subtracting the daily rate multiplied by the number of elapsed days to the indicated time. The watches were usually kept set on London time, and the difference between London (Greenwich) noon time and local mid-day, when the sun was at its highest, gave the longitude. Every 1 hour difference from Greenwich is equivalent to 15° of longitude.

The dial of this watch is signed "Lund & Blockley - To the Queen - 42 Pall Mall, London", with a serial number of 2/958. The silver case is hallmarked with London marks and the date letter for 1878/1879, a serial number corresponding to that on the movement, and the maker's mark "PW" for Phillip Woodman of Benjamin Woodman and Sons, first registered with the Goldsmiths Company London Assay Office on 29 June 1857 at 56 Great Sutton Street, Clerkenwell, London, then on 11 July 1871 recorded as having moved to 33 Smith Street, Northampton Square, Clerkenwell. Rather sensibly the cap is securely attached to the case by a silver chain - not pretty, but very functional. The back is engraved "A. W. Craig Royal Navy".

Royal Geographical Society

Between 1878 to 1929 some 40 watches were either purchased by or gifted to the Royal Geographical Society of Great Britain for use on expeditions to places where extreme climatic conditions were encountered, such as the tropics and the polar regions. Of these, 34 were waterproof explorer type, although the Society never refers to expeditionaries as explorers but always as travellers, and refers to these watches as travellers' watches. Rather understandably, because they want to distinguish these watches from the more mundane travel clocks, most dealers and collectors refer to them with the rather more romantic name of "explorers' watches".

The Society purchased most of its watches through one main supplier, Lund and Blockley, which in the spring of 1890 changed its name to Herbert Blockley & Co. The watches were finished in Clerkenwell from ébauches or rough movements bought in from Prescot in Lancashire by the well known watch company Usher and Cole (one of the great watch companies of the time), eventually bought out by Camerer Cuss, another well known London watch company, in the 20th century.

One of these RGS watches was sold by sold Steve Bogoff of San Francisco. You can see it at RGS Explorers' Watch. It is is virtually identical to the Admiral Craig watch illustrated above. Steve's watch has the same wording on the dial, with the serial number 2/951 indicating that it was made before but at around the same time as the watch in the pictures, and it has "Royal Geographical Society" and the number "5" engraved on the back, making it RGS No. 5. Steve's site also had details of two other watches when I looked.

Rather unusually, RGS No. 5 is key wound but stem set - the crown is only used to set the hands, the spring is wound by a key inserted through a hole in the back of the case. A screw-in plug seals the hole for the winding key. This is the opposite of the later explorers' watches as discussed above. At first I thought this must be an error in the description, but I have looked again at the pictures and the position of the screw in cap on the case back does confirm that it is key wound. RGS No. 5 was an early watch, part of a batch ordered in 1878. These were made up from fairly ordinary movements, hence the stem set key wind, popular at the time, and the curious screw-in cover on the back which has to be opened every day. This design was obviously not ideal and was quickly dropped in favour of the later stem wound key set type, which continued almost unchanged until the late 1920s. The "Admiral Craig" Watch is amongst the earliest of this final version of the watch.

David Penney also showed two explorers' watches, one made by Fridlander hallmarked London 1890 and engraved on the back with "Royal Geographical Society RGS No. 21.", the other supplied by Herbert Blockley, made by Usher and Cole, hallmarked London 1893, casemaker again Phillip Woodman.

Not all explorers' watches were commissioned by the Royal Geographical Society. There is no data for how many of this type of watch were produced, but the two mentioned above which have "Royal Geographical Society" together with a Royal Geographical Society serial number indicate how the Royal Geographical Society watches were identified. Explorers' watches that don't bear the engraved Royal Geographical Society name and a serial number were not commissioned by the Royal Geographical Society. The two other explorers' watches listed on Steve Bogoff's web site don't have the Royal Geographical Society name and a serial number, and the watch pictured here, as well as another explorers' watch by Herbert Blockley of St James listed by Pieces of Time, are both similarly not engraved with the Royal Geographical Society name and a serial number. Following this logic, of the 6 pieces I have noted (2 by Pieces of Time, 3 by Steve Bogoff and 1 by David Penney), only two have the Royal Geographical Society name and a serial number. So I think the Royal Geographical Society series of 40 or so watches were a minority of this type of watch and many more were made. An hermetically sealed watch of this type would certainly appeal to mariners for instance.

Thanks to Peter Burt, a member of the Royal Geographical Society, for much of the information here about the RGS and these watches. Peter is researching the Society's archives and writing a paper on the watches of the RGS, many of which have wonderful histories and entertaining stories to tell of the travellers who borrowed them (and apparently mostly returned them).

Smith & Son Explorers watches

Scott in hut 1911
Scott in hut 1911: Click to enlarge

Watches of this design with a screw cap over the crown were sold by S Smith & Son as explorers' and travellers’ watches. Judging from the very distinctive shape of the screw cap over the crown, Smiths appear to have sourced their watches from Nicole, Nielsen & Co. Ltd.

One Smith & Sons' explorers' watches was with Captain Robert Falcon Scott on the Discovery expedition of 1901 to 1905, and on the ill-fated Terra Nova Expedition, 1910 to 1913.

The picture here of Scott in his hut 1911 shows two watches on the back wall. One of these, the watch on the left, is an alarm watch, possibly made by Junghans, currently in the British Horological Institute museum. Scott used this watch to wake him every two hours so that he could exercise his hands and feet to avoid frostbite. The second watch towards the middle of the picture is the Smith's explorers’ watch, currently at the National Maritime Museum in Greenwich.

Who made the waterproof cases?

The explorers' watches made by Usher & Cole had their cases made by the company of Phillip Woodman in Clerkenwell, London. The one known example by Fridlander of Coventry had a case by the company of John Hawley of Coventry.

Back to the top of the page.

Fitch 1879 Waterproof Watch
Fitch 1879 Waterproof Watch

Ezra Fitch - 1879 Swing Ring Case With Screw Cap

On April 22nd 1879 US patent number 214642 was granted to Ezra C. Fitch. The principal features of this patent are a case without an opening back, a screw on bezel, and a removable cap enclosing the crown. The cap enclosing the crown is of course essentially the same as the explorers' watch described above, which it appears came first, but whether Fitch conceived the idea without seeing an explorers' watch I don't know. The idea is not exactly rocket science so Fitch may well have conceived it independently.

This patent by Fitch also introduced a way of fitting the movement to the case so that it could be easily removed, the "swing ring" case design.

In the patent Fitch says that the bezel is formed with an internal screw thread which engages a corresponding thread formed on the middle part of the case, and as the bezel is screwed down it forms a tight joint with the case which is "proof against the entrance of dust or moisture". Fitch envisages that a small groove may be turned in the face of the shoulder on the case to receive a packing ring to make the "tightness of the joint more secure and certain, if found necessary", and that the face of the bezel is formed with a milling around the edge as shown in Fig. 2, to give a grip to enable the bezel to be readily screwed on or off.

Fitch now confronts the problem of locating the movement in the case. He has specified that the case has no opening back, so the movement cannot be inserted from the front and held in place by case screws inserted through the back. Fitch is designing the case for use with American negative set movements, so he doesn't need to worry about how to connect the stem to the movement. Using a carrier ring for the movement which could be simply dropped into the case is an obvious idea from existing practice, but what would stop it from rotating in the case, and how would you get it out again? The movement could be secured rotationally by a slot and key, which would be good engineering practice, but unless the carrier ring was held down by the bezel, or was a very close fit in the case, it would rattle. Holding it down by the bezel would required a very precise dimension from case front to back, which was not possible with the thin shell case construction, and making the carrier ring a very close fit in the case would mean that it was difficult to get out.

Fitch conceives the idea of hinging the carrier ring to the middle part of the case, the "swing ring" design. Using a hinged carrier ring solves both problems or rotation and removal. The carrier ring has to be tapered to allow it to swing into the case, and the widest part, which enters the case last, can be made a tight fit in the case so that there are no rattles, and, as a bonus, the hinge stops rotational movement, so no need for a key and slot - two birds killed with one stone.

There are two problems with Fitch's design. The first is that the lip at 6 o'clock which you must catch with a finger nail to lift out the swing ring is very close to the seconds hand. A slip can result in you catching the seconds hand and breaking the end of the fourth wheel pivot which the seconds hand is mounted on. The second problem is the danger of bending the stem if you don't withdraw it before trying to swing out the movement. These probably never occurred to Fitch - I can't see any reason why the hinge couldn't have been at 6 o'clock with the catch at 12, which would have solved both problems: the catch would be remote from the seconds hand, and there would be no leverage to bend the stem if you forgot to withdraw it.

To seal the gap where the winding stem enters the case, Fitch provides a removable stem cap "D" which screws on the end of the pendant, the tube which carries the winding stem through the watch case, and encloses the end of the stem and the crown "k". Fitch notes that any method of attaching the cap to the pendant may be employed, but says that a screw thread is preferred because the cap can be screwed down tightly to meet a shoulder on the pendant forming a "perfectly tight joint". Fitch notes that a packing ring may also be used on the shoulder of the pendant, similar to that of the bezel, if found desirable.

Back to the top of the page.

Ezra Fitch - 1881 Screw Down Crown

In 1881 Ezra C. Fitch obtained a US patent on a development of his previous removable cap, using the watch crown itself as the cap. This was the invention of the screw down crown. Fitch was granted US patent No. 237,377 for this invention of 8 February 1881.

The image below shows some details from the patent. You can see that the crown is internally threaded and screws down onto the pendant, the base of the crown making a seal against the shoulder "e" on the pendant.

Fitch 1881 US patent No. 237377
Fitch 1881 US patent No. 237,377

Fitch specified a left hand thread for the crown and pendant. The reason for this was to use the winding ratchet to enable the crown to be screwed down once the watch was fully wound. The user unscrews the crown by turning it in the direction of winding. When it is unscrewed, the crown can be turned backwards, using the ratchet, and forwards to wind the watch. When the mainspring is fully wound, the crown can no longer be turned forward; the ratchet and the left-hand thread allow it to be screwed down onto the pendant to seal the watch. If a right hand thread was used, when the watch was fully wound, it would be impossible to screw the crown down onto the pendant and the watch would be open to dust and water.

There is a major problem with this design. If the watch is fully wound and the crown screwed down, and then the user notices that the hands need to be set to the correct time, he is in a pickle. The crown cannot be unscrewed with the spring fully wound, because that prevents the crown being turned forward to unscrew it. He must wait until the watch has run down some before he can unscrew the crown to set the hands.

First Commercial Waterproof Watches

American Watch Co. screw down crown.
American Watch Co. screw down crown © Jerry Treiman
Waltham advert from 1885

Ezra C. Fitch became president of the American Watch Company of Waltham in 1883, and Waltham ‘dust proof’ watches with screw down crowns to his patent were produced by the American Watch Company in the 1880s. The picture above of one of these watches was kindly given to me by Jerry Treiman. The advert shown here is from 1885 and shows a watch in one of Fitch's swing-ring cases with a screw on bezel and screw cap or crown.

The Achilles heel of Fitch's design is that the threads are formed on the outside of the pendant and the inside of the cap. This is a perfect place to pick up dust and muck that would cause the threads to wear quickly, which would be made worse if the watch case was made of gold or silver, or even nickel, which are all relatively soft. Even though the threads are enclosed when the cap is screwed down, this would still be a problem. Manually wound watches, as all watches were at the time, needed to be wound up every day, which allowed dust to get in over time. Thread wear was a problem, as the threads on the watch in the picture show. The same problem of wear in the threads on the pendant affected the early Rolex Oyster watches.

Although these watches were commercially available and advertised by American Watch Company of Waltham, the design doesn't seem to have achieved great commercial or popular success. Presumably a waterproof watch, with its extra complication in windng and setting, wasn't found to be necessary or worthwhile by the watch-buying public.

Back to the top of the page.

Almon Twing - Screw Down Crown with Clutch

Twing 1881 US patent No. 243011
Twing 1881 US patent No. 243011

A few months after Ezra Fitch registered his screw down crown patent another American inventor, Almon Twing of Waltham, was granted a patent for a screw down crown on 14 June 1881.

Twing's design was superior to Fitch's because it incorporated a clutch into the crown and winding stem assembly. This allowed the crown to be unscrewed even when the mainspring was fully wound. When the crown being screwed or unscrewed on the pendant, the clutch allowed the crown to turn freely relative to the stem. When the crown was unscrewed and free of the pendant, the clutch engaged the crown with the stem so that when the crown was turned the stem also turned, enabling the watch to be wound and the hands set. It also enabled the use of a right hand thread for screwing down the crown, the way that most people are familiar with.

In the picture from the patent I have coloured the two parts of the clutch red and yellow, the red bar passing through the winding stem and the yellow yoke attached to the crown. Fig 5. shows the crown screwed down with the yoke clear of the red bar so the crown can turn freely with respect to the stem. In Fig the crown is unscrewed and sprung clear of the case and the red bar has dropped into the yoke, coupling the stem and crown rotationally. The crown and stem can then be rotated to wind the movement, or pulled out further to set the hands.

Once the winding and hand setting is completed, the crown is pushed back towards the case against the pressure of the spring, disengaging the yellow yoke from the red bar. The crown can now be screwed down onto the case with a right hand thread, and because it is disengaged from the stem it can be unscrewed at any time to set the hands, even if the mainspring is fully wound. This kind of action will be very familiar to anyone with a modern watch which has a screw down crown.

This design of Twing's doesn't seem to have actually been produced in a watch, which is rather a shame because all the features which made the supposedly revolutionary Rolex Oyster waterproof some 45 years later had already been invented by 1881 - the screw back and bezel, and the screw down crown with a clutch enabling it to be unscrewed at any time.

Back to the top of the page.

Alcide Droz & Fils l'Imperméable 1883

impermeable trademark
Impermeable trademark 1883

Alcide Droz & Fils registered the company its name as makers of watches specialising in waterproof watches, and registered a trademark of an eagle carrying a watch inside a border with the words "Impermeable" and "Brevet dan tous pays" (patented all countries). They patented in Britain (UK patent 2624 26 May 1883), and in 1884 in the United States (US patent 307027 21 October 1884), a watch they called l'Imperméable (The Impermeable). They won a diploma at the Swiss national exhibition in Zurich for good fabrication and interchangeability of main parts of stem wind watches, chronographs and waterproof watches.

The impermeable watch had a screw bezel and no opening back to the case, and a screw down crown similar in principle to the design patented in America in 1881 by Ezra Fitch, including the use of a left hand screw thread. The wording of the UK patent bears a striking resemblance to that of Ezra Fitch's 1881 US patent, but Droz didn't simply copy the Fitch patent even if they knew of it. The design of the Droz l'Imperméable is different in detail, sufficiently different from Fitch's design in order for Droz to secure a patent in the US.

It is a principal of patent law that something that has already been invented cannot be patented – the principle of “Prior Art.” Designs that have been patented cannot be patented again, even after the first patent has expired, and in theory once a patent has been established in one country it should not be possible for someone else to copy the idea and obtain a patent in another country where patent treaties exist between the two countries. Although transatlantic patent treaties were in place at the time, means of communication and search were not so sophisticated as now and sometimes the patent examiner in a European country might not realize that there was prior art in the US. But the fact that Droz was able to obtain a US patent only a few years after Fitch shows that his design was sufficiently different to be regarded as a different invention.

Droz UK patent 2624 1883
Droz 1883 UK patent 2624

The figure in the US Droz patent is not very clear so I obtained a copy of the British patent and the difference was revealed. The figure here is taken from the British patent and I have cleaned it up to make it clearer without totally redrawing it.

The fundamental difference between the Fitch and Droz designs is that in Fitch's design the threads are formed on the outside of the pendant and the inside of the cap whereas the Droz design has the threads formed on the stem and inside the pendant. In this place they are much better shielded from dust than Fitch's exposed threads. The stem is made of steel, and the threads inside the pendant could also be made as an insertable plug, which would make the design much more resistant to wear.

In the figure reproduced here the crown has been unscrewed and is in the winding position. The thread on the stem and the corresponding thread inside the pendant are left handed. The hand of these thread is important because once the watch is fully wound the crown can no longer be turned in the clockwise or right hand direction. The left hand threads allow the crown to be screwed down using the freedom to turn in the anticlockwise or left hand direction conferred by the winding ratchet.

After the watch was wound, and the hands set if necessary, the crown would be pushed down so that the threads on the stem below the crown engaged with the threads inside the pendant, and the crown screwed down so that a watertight seal was formed where the lower edge of the crown came into contact with a shoulder on the pendant, as I have indicated with a red arrow. Droz also says that the top end of the pendant will contact the inside of the crown, as I have indicated with a green arrow, to make a double seal, although this would be difficult to achieve in practice; one contact would be made before the other unless the machining was incredibly precise. The idea of including a gasket or sealing washer inside the crown doesn't seem to have occurred to Droz, which only goes to show that such items didn't really exist in the nineteenth century, before the invention of synthetic gasket materials.

This similarity between the two patents probably wouldn't happen today because the two ideas are so clearly similar and examination is more rigorous, although Droz dressed up his patent with a lengthy description of a new keyless work – perhaps deliberately to confuse the patent examiner. It might be thought that if Fitch wanted to use internal screw threads like the Droz patent he would be prevented from doing so, but he would have been able to challenge the validity of that aspect of the patent because it was so clearly similar to his, although this can be an expensive business.

Back to the top of the page.

Stauffer Waterproof Watch

Horological Journal December 1884
Horological Journal December 1884

In a letter published in the BHI Horological Journal of December 1884, Stauffer described a "hermetically sealed" or "dust-tight" watch case, illustrated with the image reproduced here.

The letter discusses the problems caused by dust stopping watches, saying that sometimes watches have to be cleaned for a second time within a week of cleaning if their owner is engaged in "dusty pursuits", or that watches in "countries of the torrid zone" are ruined as a result of dampness finding its way inside the case, and that these considerations, besides the danger of accidental immersion in water or exposure to clouds of fine dust, have led to the patented invention shown in the picture.

The letter says that the chief difficulty in making an impervious case is sealing the aperture through which the winding stem passes. The illustration shows a short section of screw thread on the stem below the crown and explains that after winding the watch a "slight turn" of the crown brings it into contact with the end of the pendant and seals the opening.

It is said that with the crown screwed down onto the pendant like this, repeated trials have shown that the watch may be immersed in petroleum or warm water with impunity. The choice of petroleum as the first test fluid was probably because it wouldn't damage the mechanism if it did get inside the case. I don't know why warm water was used; perhaps whoever performed the test didn't want to get his hands cold.

When I first read the letter in the Horological Journal I assumed from the way it was worded that it was Stauffer that had patented the invention, but a search through British and Swiss patents failed to reveal any such patent. Then I realised that the design is identical to the "l'Imperméable" (The Impermeable) design patented by Alcide Droz & Fils, British patent 2624 26 May 1883 and United States patent 307027 21 October 1884. The dates tie in nicely, the short piece of left hand thread on the stem shown in the image in the Horological Journal is identical to thread shown in the Droz British patent, and the way that the crown screws down onto the end of the pendant is the same as the Droz invention.

Stauffer June8815
Watchmaker, Jeweller and Silversmith 1885

The entry from a directory in The Watchmaker, Jeweller and Silversmith of June 1885 shown here lists Stauffer Son & Co. of 12, Old Jewry Chambers and La Chaux-de-Fonds and says that they are Manufacturers of the "Waterproof" watch and the "Atlas" Machine-made levers.

The Atlas name for lever watches was a Stauffer trademark, registered in London in 1885, but the reference to Stauffer being manufacturers of the waterproof watch, when taken together with the similarities in design of the Droz l'Imperméable and the illustration accompanying the letter, implies (to me at least) that Stauffer were manufacturing waterproof for Droz watches to the design in the Droz patent.

There is more about the history of the company on my page about Stauffer, Son & Co.

Back to the top of the page.


There is a story, which apparently originated with the son of Constant Girard-Perregaux, that in 1879 the German Emperor Wilhelm I visited the Berlin Trade Fair and saw some experimental wristwatches made by Girard-Perregaux. It is said that he gave an order for 1,000 of these for the German Imperial Navy, and that as many as 2,000 were eventually delivered. Because of this story Girard-Perregaux claim to be the first manufacturers of wristwatches in significant volume.

Unfortunately, nothing is known about these wristwatches apart from the story. The archives of Girard-Perregaux were partially lost some years later, there are no records of such a watch being exhibited at the Berlin Trade Fair, or being used by the German Navy, and there are no pictures of anyone in the Navy wearing one. Over the years there have been many attempts to locate one of these watches, or any other evidence for their existence, but none has been forthcoming. This is surprising if there were thousands produced and, in the absence of any evidence, most researchers now believe that the story isn't factual.

Back to the top of the page.

François Borgel

In 1891 François Borgel of Geneva patented a water resistant watch case which was not as water tight as the cases with screw caps enclosing the crown or screw down crowns, but which provided a higher degree of sealing than the standard case of the day without the inconvenience of the separate cap enclosing the crown, or a screw down crown, and it is surprisingly watertight.

How Waterproof is a Borgel Screw Case?

When I first started collecting Borgel watches I read statements that the Borgel screw case was not very waterproof; that it didn't have a waterproof crown, and that the pin-set was not waterproof. At first I went along with this view, but as time went on I started to question it more and more. I now think that Borgel screw cases were much better sealed than many people appreciate and were in fact waterproof in the way that that was understood at the time.

François Borgel advertised his screw watch case as "imperméable", which strictly means "not allowing fluid to pass through", so it is evident that he considered his screw case to be waterproof. Borgel and the people who worked with him were skilled craftsmen and inventive engineers. Although today we are surrounded by modern technical marvels that Borgel and his contemporaries would be amazed by, the laws of physics have not changed over the last one hundred years, and people haven't become any more intelligent, so I think it would be arrogant to simply dismiss the Borgel screw case as "not very waterproof" without considering it properly.

Borgel crown detail
Three Potential Ingress Points

A note on terminology: we all know that standards of advertising have changed since 1891 and that the use of terms such as imperméable or waterproof has been tightened up since then, so that even the Omega Seamaster that I am wearing as I write this is called "water resistant to 600m/2000ft" rather than "waterproof". But in the context of a Borgel screw case watch what I think Borgel himself meant by imperméable is that it wouldn't let in dust or moisture during everyday use. And that is what is meant mean here by the term waterproof.

It is evident that by eliminating the case back joint (joint in terms of a junction between two parts, not the case maker's term for a hinge) in his 1891 patent design, Borgel had produced a watch case that was already better sealed than the typical case of the time with a jointed, snap-closed, case back. When new, the screw assembly of the case could also produce a tighter joint where the bezel meets the case, although today many of these are slack because the case has been unscrewed may times over the years.

So just how waterproof was Borgel’s one-piece screw case in principle? Ignoring the point where the crystal is set into the bezel, which can be made tight in the factory and does not need to be disturbed later, there are three areas where water might get in, as shown in the picture, (1) the joint where the bezel meets the case, (2) the pin-set used when setting the hands, and (3) the pendant or stem tube where the winding stem enters the case. Let's look at each of these in detail:

1. Bezel to case joint. The need for the movement to stop rotating when the 12 on the dial is exactly at the 12 o’clock position means that careful adjustment is necessary to get the bezel to screw down tightly onto the case. This is easily achieved by adjusting the height of the threaded carrier ring, a slight reduction in height makes a tighter seal. I haven't made a separate drawing to show this joint but if you want to see a cross section it is the joint where the red bezel meets the green case in the drawing in the section entitled The Borgel Case in Detail.

The tightness of the bezel to case joint relaxes due to wear in the screw threads over the years, and on some Borgel watches the bezel is now positively quite loose. This is made worse because most Borgel cases are gold or silver and their threads are more prone to wear because they are relatively soft materials. This gives a misleading impression about how good the seal would have been when the new case left the Borgel factory in Geneva. Borgel cases with unworn threads screw up smoothly and the joint between the bezel and the case is tight. All new, factory fresh, Borgel screw cases would have been tight like this.

Pin set push piece
Pin-Set Push Piece
Borgel crown detail
Borgel Crown Detail

2. Hand-set push-pin. The push-pin for the pin set hand set mechanism is held in place by a flat piece of spring steel that wraps most of the way around inside the case as shown in the figure. The flat piece of spring steel is wider than the push pin that is welded into it. The flat spring covers the inside of the hole though the case for the pin. I don't think this happened by accident, I believe that the spring steel strip was carefully designed to close the hole and prevent entry of dust and moisture. Obviously this joint is open when the hands are being set, but that only happens relatively infrequently and the user can choose when to do it. The same consideration applies to a screw down crown, which must be unscrewed in order to set the hands. In both cases the owner is unlikely to do it when water might get into the watch.

3. Crown to pendant or stem tube joint. When the movement is screwed fully home and the crown released it is pulled onto the end of the stem tube by the spring that keeps the outer part of the split stem engaged with the part in the movement. This is shown in the figure "Borgel crown detail". I have made the spring red and added a red arrow showing how the spring pulls the yellow crown down onto the end of the green pendant, making quite a tight joint between the crown and the pendant or stem tube.

The Borgel crown is similar in this respect to a screw down crown where the screw thread keeps the crown tight against the end of the stem tube. In the Borgel screw case the spring holds the crown against the end of the stem tube. This is not described in Borgel’s patent but I think it was an intentional design feature that was included as an improvement to the patented design. Obviously the crown to pendant joint is opened if the crown is pulled away from the watch, but this only happens if the movement is being removed from the case.

More waterproof than you might think

These considerations made me realize that the Borgel screw case was carefully designed and does provide good resistance to the ingress of dust and water in all three areas; the bezel, crown, and push-pin joints.

This is evidenced by the usually excellent state of preservation of movements in Borgel screw cases, which is usually far better than those in ordinary cases.

A Borgel under water
A Borgel Case Under Water

Obviously all three joints are metal-to-metal joints with no gaskets. But there is nothing wrong with a metal to metal joint if the mating faces are smooth; in fact in many respects you are better off if you don't have to reply on a gasket, and there were no good gasket materials available in Borgel's day, it was a choice of leather or string. Natural rubber was too prone to perishing and modern "O" rings made of synthetic material only came along much later in the twentieth century.

Which all still leaves open the question "just how waterproof is a Borgel screw case?" To try to answer this question I decided to try an experiment. I took one of my Borgel watches, not one of my best ones for fairly obvious reasons, and removed the movement. This particular watch has suffered from someone trying to lever the movement out, so there are a few gouges around the bezel, and the crown and push-pin are well worn.

Even though it was not in “factory fresh” condition, when I submersed it in water in a sink for a few minutes as shown in the picture – you can see the water level at the top of my thumb – and it did not let in water, either through the bezel joint, the crown or the push pin. I think this vindicates the Borgel screw case as being designed and manufactured to be waterproof.

Of course I’m not about to go deep sea diving in any of my Borgel screw case watches, but it does show that the Borgel screw case, even a rather battered one like the one I tested, is more “waterproof” than many people today give it credit for. I am sure that a newly made case leaving the factory would be quite “tight”, and without doubt very much superior in this regard to the standard jointed watch cases of the time.

A Borgel Watch in the Modder River

A Borgel watch in the Modder river
A Borgel watch in the Modder river: Click image to enlarge

An inadvertent practical demonstration of the impermeability of the Borgel screw case is related in the article from “The Tatler” magazine of March 1915 reproduced here. It describes a Borgel cased watch that spent several days in the Modder river during “the South African War”, meaning the second Boer War (1899 - 1902).

The watch was rescued from the river and, after being used by the original owner's brother for many years on the West Coast of Africa, it was returned to the Goldsmiths and Silversmiths Company in 1915 as an interesting curio proving the excellence of their watches. It was exhibited at their showrooms and, although the case was very rusty and could not be opened, the watch was still a reliable timekeeper!

The article does not mention that the watch has a Borgel case. It was purchased from the Goldsmiths and Silversmiths Company Ltd. in the early years of the War, so probably in 1899 and is described as a “Service Watch” with an oxidised steel case that cost £2 10s.

The advert reproduced here is a page from the Goldsmiths and Silversmiths Company's catalogue of 1901 showing the Company's Service" Watch, described as “The most reliable timekeeper in the World for Gentlemen going on Active Service or for rough wear.” The watches illustrated all have Borgel screw cases, the watch in the centre clearly shows this.

1901 Goldsmiths Advert
1901 Goldsmiths Advert: click to enlarge.

The page shows that theses watches were available in an oxydised steel case at £2 10s, exactly the same description and price as the Modder River watch. Taken together with the descriptions of the Modder River watch as a Goldsmiths and Silversmiths Company Service watch, there can be no doubt that the Modder River watch was one of these.

The same watch was also made with silver or 18 carat gold cases, at considerably greater cost. The silver and gold cased watches are illustrated with joints at the bottom of the case, an error by the illustrator.

Towards the the bottom of the page, an “UNSOLICITED TESTIMONIAL” dated June 7th 1900 says "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 Prince of Wales' North Staffordshire Regiment was formed in 1881 and served all over the Empire. The 2nd Battalion was mobilised to South Africa in 1899 and remained there until 1902. The captain's watch was cased in the oxidised steel case shown in the middle picture and worn in a leather wristlet. This was exactly the same model as the watch in the Modder river. The oxidised finish was intended to prevent rust, but this was not very successful in damp conditions, as both the Modder River watch and the captain's watch showed.

At £2 10 shillings, the price quoted in the Tatler article, the steel case was considerably cheaper than a silver case, which increased the price of the same watch to three pounds ten shillings, or the ultimate 18 carat gold case at twelve pounds. The process of oxidising the steel is described at Black steel watch cases.

A Borgel in a Washing Machine

A long standing Borgel collector wrote to me as follows:

Re: Borgel watches water-resistance

You mention how you carried out an experiment into Borgel's water resistance. Over the week-end I carried out an unintentional experiment. I left my latest Borgel (a Longines) in the pocket of my jeans when I washed them! Imagine my horror when I noticed a lump in the pocket when I took the jeans off the line and it was not my customary soggy tissue but the Borgel. When I opened it there was not a drop of water, the inside was bone dry. Who needs Rolex Oysters when you have a Borgel.

Yours Thomas, 7 June 2016.

An unsolicited and amazing demonstration of the waterproof capability of a Borgel case in good condition.

Conclusion: Waterproof!

The Borgel case was waterproof – to the standard understood at the time; it wouldn't let in water during everyday use. It must be remembered that people didn't expect to go swimming or diving wearing their watches, or rather carrying them in a pocket in their bathing costume since pocket watches ruled the day when François Borgel was designing his screw case. Recreational diving didn't come along until Commander Yves le Prieur invented Scuba diving in 1925, and Omega launched the first qualified "dive" watch in 1932 with the Omega Marine.

The Rolex Oyster is often regarded as the first waterproof wristwatch, although there were many other waterproof watches, and even waterproof wristwatches, before the Rolex Oyster, as I relate on my page about waterproof watches. The Rolex Oyster had a better sealed crown than the Borgel screw case, and there was no pin-set for setting the hands, but at first the Oyster case was screwed together by hand just like the Borgel case, using milling on the bezel and case back identical to that seen on Borgel cases. It wasn't until 1931 that the "Easy Oyster opener" was introduced to allow these cases to be screwed together more tightly than could be achieved by hand, and later still that slots or flats for keys for watch cases were introduced – most famously by Taubert & Fils who took over the Borgel company in 1924. Hans Wilsdorf didn't claim the Rolex Oyster was suitable for diving; it probably simply didn't occur to him, leaving the field open to Omega.

For use in the dusty, damp, and often very wet, conditions of the First World War front line trenches in France and Flanders, the Borgel screw case was well up to the job. This is why so many of the adverts during the war for "Service" or "Military" wristwatches, trench watches intended for Army officers getting their outfit together to go to the Western front, are for wristwatches with Borgel cases.

You can read more about this case design on my Borgel page.

Back to the top of the page.

Gilbert Dennison

Dennison 1915 patent No. UK 1390
Dennison 1915 patent

Fitch's 1881 patent for a screw down crown seems to have slipped into obscurity, or at least not been widely known outside America, because in 1915 Gilbert Dennison, of the Dennison Watch Case Company of Birmingham, England, and grandson of Aaron Lufkin Dennison, was granted British patent No. 1390 for a screw down crown very similar to Fitch's design, including the left-hand screw thread that allowed the crown to be screwed down after the watch had been wound and set. There were some minor differences between Dennison's design and Fitch's, but not very great.

In the patent, Gilbert Dennison noted that in A. L. Dennison’s Patent No. 356 of 1872, it was proposed to provide a packing inside the pendant that formed a seal against the stem but there was no way to ensure that, after a small amount of wear, this seal would remain watertight. Gilbert Dennison's solution to this problem was to place a ring of flexible packing material in an annular recess inside the crown, indicated by arrow 1 in the figure. When the crown was screwed down, this ring of packing material was trapped between the crown and the top of the pendant and compressed, forming a watertight seal.

The design had all of the deficiencies of Fitch's design, the external left hand thread exposed to dust and dirt, and the lack of a clutch, meaning that the crown could not be unscrewed with the watch fully wound. All in all it was not a great invention.

Philip Priestley records that in 1913 Gilbert Dennison collaborated with Mr M L Bateman in the design and development of waterproof watches for the "fateful Scott Antarctic expedition of 1914/16". However, Scott's last expedition started in 1910 and he died on the ice shelf at the end of March 1912. Scott's watches from this expedition are well known. One was an alarm watch that he used to remind himself to take regular activity to avoid frostbite, this watch is in the BHI collection at Upton Hall. The other watch was a waterproof explorers' watch supplied by S. Smith & Sons that is in the collection of the National Maritime Museum at Greenwich. I have not been able to discover details of any other waterproof watches that were used on that expedition, but as Scott's last expedition concluded in 1912, it appears that Philip was mistaken in at least some aspects.

Philip also says that in 1914 Dennison produced a watch with a special water resistant case for Sir Ernest Shackleton’s 1914 Imperial Trans-Antarctic Expedition expedition to Antarctica and shows a photograph of the watch, supplied by John Purser & Sons Ltd. of Cardiff. This watch has an unusually large diameter pendant and bulky and crown, which suggests that extra space was made to incorporate the ring of flexible packing material inside the crown of Gilbert Dennison's patent design.

Back to the top of the page.

The Submarine Wristwatch

In December 1917 at the height of the First World War (World War 1, WW1) the following brief article appeared in the British Horological Institute's "Horological Journal". It reports a waterproof wristwatch created at the request of two British submarine commanders. I think it is rather fascinating so I have transcribed it here in full.

In fact, the Horological Journal was rather late in reporting this watch, because there is evidence that the “Submarine” wristwatch had been in use since October 1915, or over two years, before the time the article appeared.

Reproduced below is the entire article as it appeared in the Horological Journal, there are no more details about the watch or the manufacturer, or unfortunately about the two submarine commanders mentioned in the article and who apparently caused these wristwatches to be made.

From The Horological Journal, December 1917.


The war has led not only to new inventions, but to the development and improvement of things previously known. In the latter category may be included the wristlet watch, little used by the sterner sex before the war, but now to be seen on the wrist of nearly every man in uniform and of many men in civilian attire. The first wristlet watch was naturally a small pocket watch fitted into a leather holder and strapped on the wrist. This was soon improved by soldering to the sides "knuckles" or loops, through which the strap was passed. But such a watch worn on the wrist was so open to dust, and so much exposed to the effects of the weather, that it quickly became dirty. To obviate this the case was next made in one piece, into which the works were screwed; but this device was found to have certain disadvantages. With the advent of war a great demand arose for a watch that would stand the hard wear incidental to "service" use, and it is claimed that the demand has now been adequately met. Two submarine commanders approached a certain firm, and asked them to consider the construction of a special watch suitable for their work. It was explained that it must fulfil certain conditions. (1) It must be water-tight; for even when a submarine is on the surface the deck is always more or less awash. (2) It must be non-magnetic; for under water the submarine is driven by electricity, and in such a limited space watches made of magnetic materials are necessarily affected. (3) As, for the same reason, a compensation balance of the ordinary kind is impossible, the balance must be of some material which shows a minimum of expansion and contraction with variations in temperature. This condition is met by the employment of an alloy of iron and nickel, which expands and contracts so little that this factor may be disregarded. (4) The face must be quite legible at any time, and as the usual yellow luminous figures, when placed on a white dial, are not really discernible in moonlight, twilight, or subdued artificial light, a black dial is used, thus making it easy to read the exact hour in any light. A watch fulfilling every one of these conditions, and fitted in addition with a small luminous seconds-hand, has now been on the market for some months, and appears to have before it a distinctive sphere of usefulness.

Submarine Watch
Submarine Watch: Made by Tavannes, Sold by Brook & Son
Click image to enlarge
Submarine watch advert
Submarine Watch Advert May 1916

One of these Submarine wristwatches is in the possession of a good friend of mine, Richard Edwards, and the pictures of the watch further down the page are reproduced with Richard's kind permission. I now also have one of these Submarine watches which is shown in the photograph here. It is in unrestored condition. The hands are black painted brass, presumably steel hands were not used because the watch had to be anti-magnetic. Unlike Richard's watch, this one still has Brook & Son Edinburgh faintly visible in grey enamel paint on the dial.

The Submarine watch is made water tight by having a screw back and screw bezel fitted with gaskets, and a waterproof gland seal in the pendant, the tube on the side of the case where the stem, the shaft connected to the crown, enters the case. This is the area that watchmakers found most difficult to seal. In the Submarine watch this seal was effected by a gland that was compressed against a smooth section of the stem by a gland nut.

The Submarine watch was made by Tavannes and advertised for sale during the First World War by Brook and Son, Edinburgh's foremost jewellers at the time who, in the 1916/17 Edinburgh & Leith Post Office Directory announced that they were “Goldsmiths to H.M. The King, H.R.H. Princess Louise, The King's Bodyguard for Scotland (the Royal Company of Archers), watch and clock makers, ...”

The advert by Brook and Son reproduced here for one of these Submarine wristwatches is from May 1916 in the middle of the First World War. No details of the manufacturer are given. This is one of the earliest adverts I have found for the Submarine wristwatch, and the first with a picture of the watch. The earliest advert I have seen is dated 15 April 1916. Brook and Son advertised that they were the sole agents for the watch. However, there is evidence that the first Submarine watches were delivered in 1915.

The article in the Horological Journal December 1917 said that the watches had been on the market for “some months.” In fact, the Submarine watch was made and sold much earlier than this, in 1915. The Scotsman newspaper of 6 April 1916 contains an advertisement by Brook & Son as follows:

The Scotsman: 6 April 1916

Naval Officer writes : — “The ‘SUBMARINE’ wristwatch purchased six months ago has been a great success.” The “Submarine” is the only water-tight Wrist Watch made.

Brook & Son, 87 George Street, Edinburgh.

This must surely be from one of the submarine commanders who originally ordered the watch, and “great success” must mean that it had been in use in wet conditions on a submarine, being the specific conditions for which the watch was ordered. The date of the advert, at the beginning of April 1916, and the six months elapsed period suggests that the submarine commander took delivery of his watch in October 1915.

At the outbreak of the First World War, the British Royal Navy Submarine Service was rather looked down upon by regular sailors in surface ships. The first Royal Navy submarine had been taken into service in 1901. The designs of the boats (submarines are always called boats) had been slowly developed before the war, but they were limited in endurance and capability. It required particularly resilient individuals to sail these underdeveloped and unproven machines on the high seas, plunging below the cold waters of the North Sea or the Atlantic, or even under the warmer but no less dangerous waters of the Mediterranean.

During the Gallipoli campaign British submarines carried out operations in the Sea of Marmara after having run the treacherous and heavily mined Dardanelles straits. HMSub E14 remains the only vessel in the history of the Royal Navy to have had two separate commanders awarded the Victoria Cross, Lieutenant Commander Courtney Boyle and Lieutenant Commander Geoffrey White (posthumously). E14 was followed into the Sea of Marmara by the even more famous E11, commanded by Lieutenant-Commander Martin Nasmith, who was also awarded the Victoria Cross after the first of three sorties and later promoted to Commander.

It seems that two (currently unknown) members of this tough, resourceful and determined class of men sauntered into Brook and Son's shop on Edinburgh's George Street some time in the spring or summer of 1915 and inquired about the possibility of obtaining waterproof wristwatches for their wet and dangerous work. They must have had some clout, because it appears that Brook and Son wasted no time in exploring the possibility with Swiss manufacturers. It is easy to imagine that the two submarine commanders were most likely well known, and probably well connected, members of Scottish society and regular customers of Brook & Son.

The premises of Brook & Sons at 87 George Street, the “spiritual home” of the Submarine watch, were taken over in the 1950s by Hamilton & Inches, who are still at the same address today, Warrant Holders to Her Majesty the Queen and Scotland's leading jewellery and luxury goods store.

Submarine Commander's watch
Submarine Commander's watch
Submarine Commander's watch
Images by permission © Richard Edwards

The Submarine Wristwatch

The Submarine wristwatch is made water tight by having a screw-on back and screw-on bezel, which are both fitted with compressible gaskets to improve their water tightness, and a waterproof compressed gland seal in the stem tube to prevent water entering the case through the hole where the winding stem enters.

All the Submarine wristwatch cases that I have seen carry the same number 3305913 and a shorter three of four digit number. The number 3305913 appears to be a case design reference number, the shorter number seems to be a serial number for the specific watch. The case measures a shade under 35mm diameter, about 34.8mm. This is a typical case size for a the First World War era wristwatch with a 13 ligne Swiss movement.

During the First World War, Tavannes supplied watches to Birch & Gaydon who were one of the premier jewellers in London at the time, later acquired by Asprey. The Langbourne has a screw back and bezel case similar to the Submarine watch. The Langbourne case is not waterproof; it does not have the gland in the stem tube or recesses for waxed cotton gasket in the screw back and bezel that the Submarine case watch has. Langbourne cases all carry a reference number 3305910, only three digits short of the reference number 3305913 seen in all Submarine watch cases. This suggests that these numbers are Tavannes case design reference numbers, and that the fully waterproof case of the Submarine watch was a development of the Langbourne case.

The first picture shows the black dial with luminous hands and numerals as described in the Horological Journal article. To make the numbers and hands easily visible in low light and in the dark they were painted with radioactive luminous paint, a clear varnish that acted as a binder containing radium and a fluorescent material, doped zinc sulphide, which glowed all the time. The numerals have lost their radium paint over the years, a common occurrence because the varnish is degraded over time by the radiation.

It is interesting to note that someone has thought carefully about making the numbers on this dial as visible as possible in low light conditions, . Watches with black dials either have the numerals outlined in skeleton form on an overall black dial, relying on infill paint to make them visible, or blocked out in white as this watch. Block white numerals such as this give the greatest contrast to the black of the dial and are clearly visible even when the paint is missing. The white background of the numbers ensured that light emitted backwards from the luminous material was reflected forward, maximising the luminous effect, rather than being absorbed in the dial as it would be with a black background. The hands are skeletonised to carry luminous paint, and unusually for a watch dial of this period, the seconds hand is also skeletonised and carries luminous paint, as described in the Horological Journal article. It is usually only the hour and minute hand that carry luminous paint and the seconds hand is a simple unadorned baton.

The next picture shows the means of sealing the winding stem. There is a gland or packing ring in the stem tube, secured and compressed by a round brass nut which is externally threaded and screws into the end of the stem tube. The original gland was oiled leather and has been replaced with one of modern rubber. The gland is compressed by the nut onto a perfectly smooth section of stem and gives a very effective seal. In this picture you can also see the threads on the middle part of the case for the screw bezel and screw back. The case back and the bezel have milling around their edges, just visible in the picture of the face of the watch above, to grip whilst turning to screw them on and off.

The next picture shows the case back, which carries the Glasgow Assay Office town mark for imported wares, two block letters F opposed and prone, the date letter "u" for the Glasgow hallmarking year 1917 to 1918, and the 925 of Sterling silver. The sponsor's mark JW appears to have been registered by James Weir of Glasgow. There is also reference (Brevet +) to a Swiss patent, but unfortunately no patent number. The recess machined into the case back inside the screw threads carries a sealing gasket. This was originally a plaited washer impregnated with either grease or wax.

Submarine Commander's watch

A longer version of this article was published in the NAWCC Watch & Clock Bulletin in 2014. At the time of writing I didn't know about the connection with Brook and Son of Edinburgh discussed on this page.
Click this link to DOWNLOAD the article in full! D11050

The movement was made by the Tavannes Watch Co. It is a Tavannes 13 ligne 3B calibre fitted with a special balance spring and balance.

The balance is solid white metal and the balance spring is a white metal, rather than the cut bimetallic compensation balance and blued carbon steel balance spring usually seen in these movements. I have tested with a demagnetiser and the balance spring does not respond to the magnetic field at all. I have not tested it for response to temperature, but I think it is safe to say that the balance spring is made from the "low expansion non-magnetic" alloy described in the Horological Journal article.

This was a fairly early use of temperature compensating alloys and throws light on another interesting area of horological development. During my research into the Rolex screw crown I tried to find out more about the two inventors of the screw down crown whose patent Hans Wilsdorf purchased, Perregaux and Perret. In the course of these investigations I came across one Paul Perret (1854 - 1903), and what a very interesting fellow he was.

Paul Perret was a Swiss watch timer, experimenter and inventor. He took out the very first Swiss patent, No. CH 1, in 1888. When Charles Édouard Guillaume announced the discovery of Invar, an iron-nickel alloy with very low temperature coefficient of expansion, Perret immediately requested a sample of the material which he made into a balance spring.

When Perret tested a watch fitted with the balance spring made of this new material, he found that rather than going more slowly as the temperature increased, the watch actually gained. This must have surprised Perret; he had discovered that Invar has a positive temperature coefficient of elasticity. Unlike a normal carbon steel balance spring that got weaker as it got hotter, a balance spring made from Invar got stronger as it got hotter.

Guillaume says that this was independently confirmed later by Marc Thury, but it was clearly Perret who made the discovery. Guillaume was only looking for a material that was dimensionally stable for his standards of length measurement, but Perret was trying to improve watch escapements and hence his interest in any new material such as Invar with properties that might be useful for balance springs.

After Perret had informed Guillaume of discovery the two agreed to collaborate on research into the elastic properties of nickel-steel alloys, which they did during the summer of 1897. The most accurate and convenient way of measuring the elastic modulus of these alloys at the time was to make them into balance springs and observe the rate of a watch fitted with them at different temperatures. Guillaume depended on Perret for this.

Paul Perret Balance Springs

On 6 May 1897 Perret registered in Switzerland a claim for a patent on an escapement with a balance spring whose strength increased with temperature sufficiently to compensate for the increase in moment of inertia of a plain (uncompensated) balance. This patent was published in Switzerland on January 15, 1898, as CH 14270, in Great Britain on February 5, 1898, as GB 25,142 and in the United States on March 12, 1901, as U.S. 669,763. Perret founded his own company to make these balance springs.

Perret balance springs
Paul Perret 1901 advert for nickel steel compensation balance springs. Click image to enlarge.

The advertisement from La Fédération horlogère suisse shown here is from September 1901. Under the title “Timing of watches” the ad says that “The best timing is obtained, especially for non-magnetic watches, with balance springs of nickel-steel, contact the manufacturer Paul Perret, Fleurier.”

Examples of changes in daily rate caused by increases in temperature are given and range from ordinary non-magnetic balance springs, which are said to vary from 15 to 18 seconds per degree centigrade, through to Paul Perret’s nickel-steel non-magnetic compensation balance spring, which is said to vary from 0 to 1 seconds per degree centigrade. The remark at the bottom of the ad says that the nickel-steel balance springs allow the elimination of the cut bimetallic balance and that balances made all of brass ("tout en laiton") give the best results.

Perret continued to work with Guillaume, and if he hadn't died in 1903 at age only 49 his name would be much better known today. After Perret's death his daughter Emma granted the rights to use Perret's patent to Spiraux Réunies.

Throughout his career Perret continued to work on compensating balance springs. In studies into balances and compensating balance springs that were published in 1905 after his death, one of the companies he mentioned working with was Tavannes. Tavannes was founded in 1891 by Henri-Frédéric Sandoz who was a talented and inventive watchmaker, designing his own calibres and the machines to make them. It is surely not a coincidence that it was Tavannes that made the Submarine watch.


The one question that puzzles me is why so little is known about these historically important watches that were waterproof, non-magnetic, and with auto compensation for temperatures effects? I have never seen them mentioned in any book or article. They were clearly fully waterproof more than ten years before the Rolex Oyster, which many people think of as the first waterproof watch, or at least the first waterproof wristwatch.

The Submarine watch was also remarkably practical compared to the Rolex Oyster - there is no need to unscrew the crown to wind or set the watch, and therefore no threads on the stem tube to wear. Thread wear was a major problem for the early Oysters before automatic winding was introduced. The Submarine watch also remained waterproof while either winding or setting the watch, which the Oyster didn't; there is no need to remember to screw down the crown after winding to make the watch waterproof again, a feature that has caused grief to many Rolex Oyster owners over the years. The compressed gasket sealing for the stem is not as ultimately waterproof as a screw down crown in withstanding water pressure at diving depths, but then Rolex didn't make any claims about this for the first Oysters and left the stage clear for Omega to make the claim of producing the first dive watch; the 1932 Omega Marine.

I suppose the answer could be found in the way the Submarine watch came about, during the depths of WW1 as the result of a request by two submarine commanders. The extra work involved in making the watch waterproof and anti magnetic would have made it more expensive. Was it regarded as too expensive to be commercially viable, or was it that no one involved saw that the public might want a waterproof watch? 1915 was long before recreational diving became popular following the invention in 1925 of Scuba diving by Commander Yves le Prieur.

The promotion of a waterproof watch as something for the average person to want or need seems to have been a particular vision of Hans Wilsdorf, similar to the way that Steve Jobs had a vision for the iPod and iPad and almost single handedly created markets for portable mp3 players and tablet computers. But without such a visionary to champion its cause this watch faded into obscurity.

NB: Do not confuse the Tavannes Submarine watch with a later design, the Harrrop "Submarine" that was made in London, or any other watches with the name Submarine.

Back to the top of the page.

Fortis "Aquatic" waterproof watch

An interesting early waterproof wristwatch is the Fortis Aquatic shown in the picture here. I haven't got round to cleaning this watch and took a quick photograph for this article because the dial retains a lot of radioactive radium paint and I don't want to disturb things until I am ready to do a full clean and restoration on the watch.

The waterproof case of the Aquatic watch was invented in 1915 by two Swiss gentlemen, Paul Ernest Jacot and Auguste Tissot. Swiss and British patents were granted for the invention. The Aquatic watch was assembled by the Fortis Watch company of Grenchen in the canton of Solothurn in Switzerland. The watch was sold with no name on the dial and simply Aquatic stamped inside the case back, and also with Rolex and Zenith brand names.

Fortis Aquatic
Fortis Aquatic wristwatch: Click to enlarge
Fortis Aquatic
Aquatic patent August 1915: Click to enlarge
Fortis Aquatic
Aquatic movement: Click to enlarge

The design of the Aquatic watch was the subject of Swiss patent CH 71715. The inventors Paul Ernest Jacot and Auguste Tissot applied for a patent on the design on 27 August 1915 and the patent was granted and published on 1 February 1916. The title of the patent was "Montre avec emboîtage hermétique du mouvement", i.e. a watch with a hermetic case for the movement. The same two gentlemen, describing themselves as manufacturers of La Chaux-de-Fonds, Switzerland, applied for a British patent for the same design, which was granted as British patent 101,345 on 28 August 1917, one year to the day after the application was made. This delay was of little consequence because in both cases the priority date, the date from which the invention was protected by the patent, was 27 August 1915.

It appears that Jacot and Tissot must have licensed the patent to the Swiss watchmaker Fortis, because all of the watches with this case design carry the name "Aquatic", a name that had been registered by Fortis so that no one else could use it.

The Aquatic case in detail

The figure reproduced from the patent shows cross sections through the case. The principal waterproof features are that the case has a screw back, no front bezel, and gasket seals for the glass and for the winding stem where it enters the case.

Doing away with the front bezel means that there is one less joint through which water can enter the case, but the movement has to be inserted from the rear of the case, which means that the normal arrangement of case screws cannot be used to hold the movement in place. The glass is also inserted from the case back.

The glass is held in place by a ring labelled j in the figures from the patent. Fig.3 shows how a screw p with a conical end is screwed through this ring and the cone bears against an internal step in the case. When the screw is tightened its conical end bearing on the step forces the ring upwards, pressing the glass against a gasket labelled "m", sealing the glass against the case. I have put a red ring around one of the p screws in Fig. 1.

The movement is held in place by the two screws labelled "r" in the figure operating on the two bars labelled "o". I have put a red ring around one of these pairs of screws and bars in Fig. 1. The bars bear against the internal step in the case and, when the screws are tightened, act as levers holding the movement into the case. The screws r are easily visible in the photograph below of the movement together with the slots in the ring j that the bars pass through.

Fortis Aquatic
Harrods Aquatic advert: Click to enlarge
Fortis Aquatic
Aquatic case back: Click to enlarge

The use of the separate j ring to hold the glass in place seems at first glance an unnecessary complication, but it has the benefit that the movement can be removed by undoing the two screws r, when it drops out from the back of the case without disturbing the glass and its gasket seal.

The opening in the side of the case where the stem enters is sealed by a gasket "w" in a cup shaped feature "u". To achieve a seal the crown is clamped down onto the gasket by the spring strip "y". This is missing from my watch, but you can see the two attachment points on the side of the case, one the tube "x" where the root of the strip was attached to the case, the other a snapping piece "1" where the end of the strip "z" snaps into place.

The stem sealing gasket was the Achilles heel of this design. It is missing on my watch and James Dowling told that Zenith & Rolex also used this case design, but there does seem to be an inherent weakness in the stem/crown design as both the Rolex pieces I have in my collection are missing both these rather essential components. The Rolex branded watches that I have seen with this case have the same movement as mine and it seems that both Rolex and Zenith purchased complete watches from Fortis.

Advertising the Aquatic watch

The advert by Harrods reproduced here from The Sketch of March 1917 is interesting, it says that Harrods test each watch in water for 14 days before putting it on sale, and that they guarantee it for three years.

The watch was available with a nickel case at two pounds and ten shillings, or a silver case at four pounds and four shillings. The price difference is quite significant, the silver case nearly doubles the price! My watch has a nickel case so it is not hallmarked and cannot be dated from the hallmark date letter.

The Harrods advert says that the Aquatic watch was specially made for Harrods and could be be obtained anywhere else in the Kingdom. This situation didn't last, in 1917 the company of Lawrence & Laurence Ltd., Watchmakers to the Admiralty, were advertising the Aquatic watch. The price was higher than Harrods at three pounds for a nickel case and five pounds for a silver case. This was an expensive wristwatch at the time.

Back to the top of the page.

Depollier "Waterproof Dustproof" watches

Another waterproof watch design was the Depollier "Waterproof Dustproof" wristwatch made by Jacques Depollier & Son. The idea behind this design originated with Auguste Jaques of Chaux-de-Fonds, Switzerland.

The first of a series of patents for this watch was awarded to Auguste Jaques and Charles Leon Depollier with the American patent number US 1172601 dated 22 February 1916. The application for the patent, and therefore the priority date, had been lodged on 9 November 1915. The same design was patented in Great Britain by Jaques and Depollier with the patent number GB 102158 on 19 Apil 1917.

Charles Depollier US patent No. 1,292,441
Charles Depollier patent

The American patent US 1172601 granted to Jaques and Depollier is identical to an earlier Swiss patent granted to Auguste Jaques on 1 December 1916, with a priority date of 24 December 1914. The fundamental idea behind the waterproof aspect of these patents was a bayonet locking mechanism that held the crown tightly against the case when the watch was not being wound or set. In order to create a waterproof seal a large gasket was required at the base of the pendant and with the materials available at the time and the exposed position of this gasket the perfect seal would not last long, especially with the watch being wound every day. Although a number of these watches were made the design was ultimately a dead end.

Auguste Jaques lodged two applications for patents on 24 December 1914, Mécanisme de remontoir au pendant and Mécanisme de remontoir perfectionné (mechanism for winding by the pendant and improved winding mechanism). These were granted approved status as Swiss patents CH73816 and CH73815 respectively on 1 December 1916.

A subsequent patent for a waterproof crown was granted to Charles Depollier on January 28, 1919, No. 1,292,441 shown in the picture. The crown has a slotted skirt "g" which bayonet locks under lugs "b" on the side of the case when pushed in and turned clockwise a quarter of a turn or so. The skirt is tapered, pressing down onto a gasket. Turning the crown counter clockwise unlocks it so that the watch can be wound and set. The case has a screw back and bezel, the back and bezel having raised slots to engage with a special key for screwing and unscrewing.

One of these watches was worn by Roland Rohlf during a record altitude height of 34,610 feet on September 18, 1919, in a Curtiss K-12 aeroplane. Advertisements celebrating this achievement not only claimed that the watch was waterproof, but that it even maintained the atmospheric pressure inside the case against the rarefied atmosphere of the high altitude!

Back to the top of the page.

Hermetic Wristwatch

Double Case "Hermetic" Watches - Frederick Gruen (US) and Jean Finger (CH)

An elementary, almost brutally simple, way of protecting a watch was to place it completely inside a larger case, with a screw-down bezel forming an hermetic seal and totally protecting the watch within. Watches employing this double case design are usually called "Hermetic".

The picture to the right shows one of these watches. The first feature that is immediately noticeable is that there is, or appears to be, no crown. The bezel is also somewhat wider than normal, and it has a milled detail on it, which gives the idea that it is designed to be gripped and unscrewed. Once the bezel is unscrewed, the inner watch can be flipped out on a hinge to allow the movement to be wound and the hands set.

Gruen and Finger patents
Gruen and Finger patents

The origin of this case design is a bit of a puzzle because there are two virtually identical patents for the idea.

The first is a U.S. patent granted to Frederick Gruen on 20 May 1919, "Wrist-Watch" patent number U.S. 1,303,888 with a priority date of May 29, 1918.

The second is a later Swiss patent granted to Jean Finger on 2 May 1921, a watch case maker of Longeau, Berne, Switzerland, "Montre a remontoire avec boitier protecteur" (stem winding watch with protective box) patent number CH 89276 with a priority date of 4 January 1921.

The image to the left shows figures from both patents, the Gruen patent on the left and the Finger patent to the right. You can see how similar they are.

In both designs the outer case is in one part with a screw on bezel. Apart from the removable bezel which carries the crystal there are no penetrations through the case. When the bezel is screwed down onto the case a waterproof seal is formed and whatever is inside the case is protected from dust, dirt and moisture. Inside the case is a small watch movement in its own case. The case of the movement is hinged to the outer case and a small projecting tab allows a finger nail to lift and pivot the inner case upwards so that the crown is accessible. The watch can then be wound and set in the normal way. After winding the watch it is swung back down into the outer case and the bezel screwed back on.

The principal difference between the two patents is that the Gruen watch is hooked to the outer case and is easily removable, whereas the Finger watch has a more permanent hinge connecting it to the outer case. This is really a trivial difference, and apart from it the two designs are essentially the same. I have seen many of the Jean Finger version, but only one of the Gruen design.

Hermetic Wristwatch open for winding and hand setting

The picture to the right shows a Hermetic wristwatch in a Finger style case with the bezel removed and the movement raised on its hinge to access the crown.

How do two such similar patents get issued within three years of each other? International patent treaties in force at the time should have protected inventions in other countries, or at least prevented the patenting of something that already existed, under the rule that "prior art"cannot be patented. Patent examiners have a duty of due diligence to ensure that patents are neither obvious nor duplications of existing inventions. But during the period of the Gruen and Finger patents, means of communication and search were not so sophisticated as now, and foreign patent offices do not necessarily track each other very well even today. Ultimately, patent law is based on litigation. If the holder of the priority patent does not realize the existence of the later patent, or chooses not to litigate, nothing happens.

The application for the Gruen patent was lodged while the First World War was still raging, and communication with Switzerland would have been even more difficult than usual. It may be that Finger never saw Gruen's patent, and maybe by the time of Finger's patent, Gruen had given up on the idea or just never heard about it. Perhaps it is not so surprising that the two patents are so similar: as I remarked before, the idea is brutally simple.

Although the hermetic case achieved the desired effect of protecting the movement from moisture, it had the major drawback that the bezel of the outer case had to be unscrewed every day so that the watch could be wound. Apart from being a nuisance to the owner, the case threads and the milling on the bezel wore quite quickly from this continuous use, so this was a far from ideal solution. However, despite these drawbacks, a number of manufacturers including Zenith, Eberhard and Rolex produced watches using this case design. It was very useful in the tropics where the heat and damp quickly corroded the movements of watches in ordinary cases, and hermetically sealed watches are sometimes referred to as “tropical watches” because of this.

It appears that Hans Wilsdorf, co-founder and managing director of Rolex liked the Jean Finger design and bought some rights to the patent, because he was granted a British patent GB 197208 on 10 May 1923 for exactly the same design, “Improvements in and Relating to Watches” with the priority date 26 May 1922. A watch using this case design was produced for Wilsdorf and Davis from 1924, and some of the cases of these watches bear the initials "JF" for Jean Finger and the words "Double Boitier Brevet Swiss Federal Cross 89276" (Double Case Swiss Patent 89276), a reference to the Jean Finger patent.

The Wilsdorf and Davis watch is often seen with the word “Submarine” on the dial. Wilsdorf registered the name “The Submarine” in March 1922, shortly before he applied for a British patent on the Jean Finger case design, which seems far too close in time to be a coincidence. The presence of the W&D sponsor's mark in the case of these watches causes some people to refer to them as Rolex watches, but there is no evidence that the Wilsdorf or the Rolex Watch Company ever called them Rolex watches.

The purchase by Wilsdorf of some rights to the patent doesn't seem to have precluded other manufacturers producing watches using the same case design. For instance I have a watch made in Switzerland for the Coventry, England, firm of Rotherham and Sons Ltd. It has a Glasgow hallmark which dates it to 1929/30, so the purchase by Wilsdorf of some rights to the patent, and the introduction in 1926 of the waterproof Rolex Oyster, didn't succeed in sweeping this case design away overnight. What seems most likely is that when the Rolex Oyster came along, Wilsdorf lost interest in the this case design.

The key part of the Rolex Oyster design, the screw down crown, was protected by patents, so anyone else who wanted to make a waterproof watch couldn't simply copy the Oyster design but had to use an alternative, like Jean Finger's hermetic case design. With the advertising around the Oyster creating demand for waterproof watches, other manufacturers were naturally keen to find something they could use that didn't violate Rolex's patents, which resulted in a prolonged the life for this rather cumbersome method of making a waterproof watch.

Jean Finger however evidently retained faith in his design, because he registered a slightly improved version of his original 1921 patent on 2 February 1929, Swiss patent number CH 138244, published 16 April 1930. The differences between the two designs are small, the later patent uses a bezel that screws into the front of the case, which allows the joint between the case and the screw in bezel to be concealed, and a different way of attaching the movement hinge to the middle part of the case. By this time the end of the road for the design was clearly in sight, and watches produced to the later patent are rare.

Back to the top of the page.

Hans Wilsdorf and the Rolex Oyster

The story of the waterproof watch would hardly be complete without Hans Wilsdorf, co-founder and managing director of Rolex, and the Rolex Oyster watch.

Rolex Oyster
Rolex Oyster. Image by kind permission
of and ©

In the Rolex "Jubilee Vade Mecum" Wilsdorf wrote "To my technical assistants, my constant refrain was, from the earliest days: We must succeed in making a watch case so tight that our movements will be permanently guaranteed against damage caused by dust, perspiration, water, heat and cold. Only then will the perfect accuracy of the Rolex watch be secured."

NAWCC Watch & Clock Bulletin

A longer version of this description of the design of the Rolex screw down crown and some of the other designs that preceded it was published in the NAWCC Watch & Clock Bulletin, December 2010.

On 30 October 1925 in La Chaux de Fonds, Switzerland, Paul Perregaux and Georges Perret applied for a Swiss patent for a winding system where the crown could be screwed down on to the case to create a waterproof seal. The patent was granted and published on 17 May 1926. There seems to be very little known about Perregaux and Perret, who are sometimes described as watchmakers and prototype makers. When Hans Wilsdorf found out about this patent he bought all rights in July 1926 and had the patent assigned to him. Wilsdorf then registered the design as British patent No. 260554 on 1 September 1926, published on 21 April 1927, and in Germany No. 443386, and the United States No. 1,661,232.

Although Wilsdorf probably thought that this was the breakthrough that he had been looking for, the Perregaux and Perret design didn't have a clutch like the Almon Twing design, but was essentially the same as the earlier and less practical 1891 Fitch design, with a left hand screw thread, consequently suffering all the drawbacks of that design. Wilsdorf must have quickly realised that this was not a solution he could offer to the public, but the technicians at Aegler quickly reinvented Twing's idea of using a clutch to disengage the crown from the stem when the crown was being screwed down onto, or unscrewed from the case.

This new screw down crown design was paired with a case having a screw back and bezel, and in 1926 the waterproof Rolex Oyster was born. The design of the first Rolex Oysters was not perfect, because the crown had to be unscrewed to wind the watch every day, leading to heavy wear of the screw threads. Most early Oysters have had their original crowns and stem tubes replaced because of this. This problem was overcome, or rather it was sidestepped, in 1931 with the introduction of the "Perpetual" self-winding movement.

You can read more about the development of the Rolex Oyster on my Rolex page. (Clicking the link will open a page in a new tab.)

Back to the top of the page.

Taubert & Fils

At about the same time as Rolex were developing the Oyster, the company Taubert & Fils, who had taken over the company of François Borgel in 1924, were developing a watch case with a screw back and cork seal in the stem tube to seal the winding stem. The benefit of the cork stem seal designed by the Tauberts was that the crown didn't need to be unscrewed to wind the watch, the owner could wind the watch with no more inconvenience than with a normal watch, and the stem was sealed all the time, even if the crown was withdrawn to set the hands.

The first watches with these cases were produced in the mid 1920s. The Tauberts patented the cork stem seal in 1929 and a screw back case with a distinctive 10 flats "Decagonal" design in 1931. They went on to supply this case to many manufacturers including Patek Philippe and Vacheron Constantin. You can read more about this case design on my Taubert page.

Back to the top of the page.

Harrop ‘Submarine’ Watch

Harrop Submarine Advert
Harrop Submarine Advert 1933
Harrop Submarine
Harrop Submarine Bezel and Gasket
Harrop Submarine
Case Back Gasket
Harrop Submarine Crown
Harrop Submarine Crown

In the early 1930s a watch with the name "Submarine" was manufactured by the company Edwin Harrop of London. The cases were made in London by Harrops and fitted with Swiss made movements that were imported for the purpose. This watch was also made in a ladies' version called the ‘Mermaid’.

This was a completely different design to the earlier Submarine wristwatch manufactured by Tavannes. The use of the same name implies that the makers of the later watch did not know of the existence of the original Submarine watch.

The cases of these watches usually carry the name "Submarine" in inverted commas, the legend 'London Made' and two patent numbers, 358370 and 362229, which both refer to British patents.

The first patent, 358370, was applied for on 16 December 1930 by Frank Wachter, a US citizen, and was accepted on 8 October 1931. The subject of the patent was a snap back case with a recessed gasket to seal the joint between the snap back and the middle part of the case.

The second patent, 362229, was applied for by Edwin Harrop of London and Wachter on 4 February 1931 and accepted on 3 December 1931. The subject of this patent was a gasket between the bezel and the crystal to seal the joint between the bezel and crystal.

The cases are very thick and heavy in comparison to most watch cases. Gold and silver versions, which appear to be the only metals used, carry the sponsor's mark EH of the London jeweller and goldsmith Edwin Harrop.

In 1918 The London Watch Case Company was listed with E. G. Harrop and A. M. Lederman as directors. Harrops must have been on the lookout for new case designs when Wachter's patent caught their eye.

The advert reproduced here dates from 1933. It says that the watches are supplied in two sizes, an 8¾ ligne ladies' model and 10½/12 ligne men's.

Cases are usually about 5 millimetres greater in external diameter than their movement, although the Harrop submarine cases were quite thick and chunky because they had to have space for the gaskets. The movement of one watch I have examined measures about 23mm or 10.2 lignes across, which must be the 10½ ligne version; movement sizes were generally rounded to a half size in lignes. The case of that watch measures 30mm across, which was a fashionable size for a man's watch in the 1930s, and is 7 millimetres greater than the movement.

On this basis, the 12 ligne version would be about 34 or 35 millimetre in diameter across the case, for men who still preferred a larger size watch. The ladies' 8¾ ligne model would measure about 20mm across the movement and the case would be about 27 millimetre external diameter.

Two images here show the detail from the second patent of the gasket seal to the bezel, and the middle part of the case with its recessed gasket. The use of gaskets like this are very simple, almost blindingly obvious, ways of sealing the two joints, and I am rather surprised that Wachter and Harrop were granted patents for these “inventions”. Patents are supposed to be granted only to protect novel inventions that must not be obvious to a person skilled in the art, two criteria that both of these patents fail to meet.

Neither of the patents mentions any means of sealing the case where the stem enters. The advertisement states that the pendant is rendered watertight by a gland.

surviving examples have a gland inside the crown. The illustration shows a cross section throughout the pendant and crown. The gland is retained in the crown by a retainer, the L shape item, which is a press fit into the crown. The gland is compressed by the insertion of the retainer and forms a seal against the pendant, the tube through which the stem enters the case.

Back to the top of the page.

Omega Marine: First Dive Watch

Omega Marine
Omega Marine. Photo by Mike Katz, ©

In 1932 Omega introduced a waterproof wristwatch based upon Swiss patent CH 146310 granted to Louis Alix of Geneva. This watch was called the Omega Marine and given the Omega reference number 679. The Omega Marine was the first true dive watch; the first watch specifically tested and qualified for diving.

Rolex had a firm grip on waterproof screw down crowns through the patented Oyster crown, so Alix's patent design used for the Omega Marine overcame the problem of making the winding stem water proof without infringing Rolex's patents by the simple expedient of sliding the whole watch inside a second outer casing. The patent was also taken out in France, Britain, the USA and Germany.

In 1936 an Omega Marine was sunk to a depth of 73 metres in Lake Geneva for 30 minutes. In May 1937 the Swiss Laboratory for Horology in Neuchâtel certified the Omega Marine as being able to withstand a pressure of 13.5 atmospheres, equivalent to a depth of water of 135 metres. These were the first tests to establish the depth capabilities of a watch and qualify its suitability for diving.

The Omega Marine was worn whilst diving by Commander Yves Le Prieur, a French Naval Officer and inventor, in 1925, of the aqualung, a self-contained underwater breathing apparatus or SCUBA. The Marine was also worn and endorsed by Dr William Beebe, the American naturalist and explorer who took up underwater exploration in the late 1920s.

Yves Le Prieur (1883 - 1963) was an interesting character. He followed his father into the French navy and served in the far east. He went diving using traditional diving equipment with a weighted belt so that the diver walked on the sea bed and a big, heavy, helmet fed with air down a tube from a pump on the surface. He learnt Japanese, became military attaché at the French Embassy in Tokyo, earned a black belt in judo and was the first person in Japan to take off in an aeroplane, a glider. He returned to Europe and during the First World War invented, inter alia, a rocket to bring down balloons and airships, and gun sights that computed the correct angle of fire. He was a creative, restless, inventor all his life.

Commander Yves Le Prieur
Commander Yves Le Prieur with his Omega Marine © Captain Jacques-Yves Cousteau and Frédéric Dumas 1957.

In 1925 Le Prieur saw a demonstration of a diver using a breathing apparatus invented by Maurice Fernez. This consisted of a mouthpiece supplied with air through a tube from the surface, a nose clamp and goggles. Le Prieur was impressed by the simplicity of the Fernez equipment and immediately conceived the idea of using Michelin cylinders as the air supply. Michelin cylinders contained three litres of air compressed to 150 kg/cm2 and were supplied by the Michelin tyre company to garages without air compressors for inflation of car tires.

For the first time this invention allowed a diver to submerge without any connection to the surface; Le Prieur had invented the self-contained underwater breathing apparatus, in French "scaphandre", rendered into English as the aqualung or by the acronym SCUBA. The use of unpressurised goggles prevented the diver from going deeper than about 10 metres because the goggles were squeezed onto his face, so in 1933 Le Prieur invented the full face diving mask, a rubber cylinder that covered the eyes, nose and mouth with a glass front to see through. The mask was supplied with air and Le Prieur remarked that the diver could breath through his mouth or nose, or both, at will, and could even talk to other divers by bringing the mask close their ear, the glass acting as a microphone.

In 1934 Le Prieur created a second version of the equipment with a full face mask and automatic pressure reducer. The first diving club was created in France in 1935 by Le Prieur and Jean Painleve, it was called the "club des scaphandres et de la vie sous l'eau", the club for divers and life under water. In 1936 the Le Prieur apparatus was officially adopted as diving gear by the French Navy.

The 1957 book "The Silent World"Ref. 2 by Captain Jacques-Yves Cousteau and Frédéric Dumas shows this picture of Le Prieur diving with his aqualung and wearing an Omega Marine. The face mask is the later version of the equipment so the picture dates from after 1934. The book tells how Cousteau started diving with Fernez goggles in 1936, and in 1939 used Le Prieur equipment for the first time. In 1942 Cousteau made an improvement to Le Prieur's apparatus by adding a demand regulator, invented by his friend Émile Gagnan, which reduced air consumption and thereby extended the length of time that could be spent under water. It made the apparatus better, but Cousteau did not invent the SCUBA.

Dr Beebe is most famous for his 1934 descent in the "Bathysphere" to a depth of 3,028 feet beneath the ocean surface. But Beebe also dived with the older heavy helmet gear and in 1936 he made a dive in the Pacific wearing an Omega Marine. Afterwards he wrote I wore my Omega Marine in the Pacific Ocean at a depth of 14 metres, where the pressure is twice the normal one. My watch sustained this test with success. Its tightness to water and dust and its robustness to corrosion represent a true progress for watchmaking science.

The Omega Marine Design

Louis Alix's design for the waterproof double case, shown in the figure from the patent, had a curved shape in an arc of a circle. Alix doesn't explain in the patent why this was: it may have been to follow the shape of the wrist, or it may have been a purely aesthetic consideration, this was the age of Art Deco after all. I don't think this curved shape was actually ever used by Omega, all the pictures of Omega Marines which I have seen have been of straight (linear) cases. The elegant curved shape envisaged by Alix would have been difficult and expensive to make at the time and challenging even today.

The watch movement, dial, and hands were contained in a rectangular section interior case. This interior case had a shoulder at the end with a groove which contained a gasket. The interior case slid into a rectangular section outer case, the end of which contacted the gasket in the shoulder of the interior case, forming a water tight seal. A large spring clip on the back of the outer case held the two parts of the case together. The clip was necessary to provide the initial seal between the inner case, the gasket, and the outer case, but as the watch was submerged, the air pressure inside the case would remain constant while the water pressure outside the watch increased, pressing the two parts of the case more firmly together, increasing the force on the gasket and making the seal more water tight.

Louis Alix patent CH 146310
Louis Alix patent CH 146310

The spring clip described by Alix is not how the case clips were actually manufactured. There were two different generations of the Marine case; the first had a massive clasp on the back of the outer case, running right from the top to the bottom. A second generation of the Marine case, from about 1935 onward, had a much shorter clasp hinged close to the bottom edge of the case more like the clip Alix envisaged.

The cases of the Omega Marine were mostly made in steel with the prefix CK, so CK 679, but they were also made in precious metals e.g. OJ 679 (OJ = Or Jeune, yellow gold). The cases were made by the company of Frédéric Baumgartner of Geneva. Although Baumgartner’s name doesn’t appear on any of the cases, his company's Poinçon de Maître is found in gold Omega Marine cases.

In his patent, Louis Alix suggests that the gasket, the item labelled "q" in the figure, should be made of rubber (" caoutchouc"). In contemporary adverts and in the book by Marco Richon OMEGA - A Journey through TimeRef 1 this gasket is said to be leather. Leather is not a very satisfactory gasket material but at the time it was probably better than the rubber that was available.

Omega Marine. Photo by Mike Katz, ©

The patent illustrated a slim crown recessed into a depression on the side of the interior case, but this was not very practical and production models had the crown at the top of the movement, at the 12 o'clock position like a pocket watch. This can be seen in the second of the two pictures here, kindly provided to me by Mike Katz.

The Marine was at first fitted with the manual winding stem wind and set calibre 19.4 T1, created in 1930, then later with the improved 19.4 T2, created in 1935, still a manual winding movement. Omega was rather unusual at the time in referring to their calibres in millimetres rather than ligne sizes, and 19.4 means these movements were 19.4 mm diameter. They were round movements, not shaped to the form of the watchcase. The 19.4 T1 and T2 calibres were available with either 15 or 17 jewels and operated at 18,000 vibrations per hour. Although the Marine would have been an ideal candidate for an automatic winding movement, Omega did not introduce their first automatic movements until 1943, with the bumper automatic 28.10 and 30.10 calibres, and the Marine was never fitted with an automatic movement.

The outer case had a sapphire crystal in the front so that the dial of the watch in the interior case could be seen. Sapphire was chosen because it was much stronger than glass and this was one of the first uses of it for a wristwatch. The watch strap was made of seal skin, which was thought to be more resistant to water than ordinary leather, and had a unique deployment type clasp. If you have one of these original clasps I would like to know.

A longer version of this description of the 1932 Omega Marine and 1939 Omega Marine Standard was published in the NAWCC Watch & Clock Bulletin, February 2012.

The Omega Marine was not an automatic self winding movement so it would have to be manually wound every day. To wind the watch or set the hands obviously meant removing the inner case from the outer. In addition to being a nuisance, this might have worn the sliding surfaces and imposed wear and tear on the sealing gasket, so the watch would need regular attention to retain its full waterproof capability. The Omega Marine would also have been an expensive watch to make, and hence expensive to buy. I would have guessed that this, together with the inconvenience of its design in daily use, would have restricted its popularity to those who really needed a fully waterproof watch or wanted something unusual and were prepared to pay more for it, which is why it is scarce and valuable today.

In A Journey Through Time1, numerous examples of the Marine are illustrated in mixtures of steel and gold, as well as 18 carat gold versions retailed by Tiffany and Cartier in New York. The case design naturally lent itself to the art-deco style in vogue at the time, and Marine's with art-deco dials and strap lugs were produced. Obviously these precious metal cases and art-deco design features weren't necessary in a diver's watch, and are in stark contract to the strictly functional steel cases and easy to read dials of today's diver's watches. It would seem that, just as today, watches with unusual technical features attracted the attention of those who like something different, perhaps because they like impressive gadgets, or to impress their friends, and the Omega Marine sold to many people who wouldn't dream of diving deeper than their local swimming pool.

In 2007 Omega added a reproduction of this watch, the Marine 1932, to its Museum Collection of vintage timepieces. The double case was made in contrasting 18-carat red and white gold, and the series was limited to 135 pieces to commemorate the official certification of water resistance to a depth of 135 metres.

The watch in Mike Katz's pictures is actually a version of the Marine produced by Omega's sister company Tissot. It is branded "Omega Watch Co. Tissot" in the case back and on the movement. Paul Brandt began the process of bringing Omega and Tissot together in 1925, and by 1930 Paul Tissot-Daguette was managing director of Omega as well as a director of Tissot. The two companies became subsidiaries of a multi-national holding organisation, Société Suisse pour l'Industrie Horlogére (SSIH) to produce a complete range of watches, and for joint sales promotions.

Patek Philippe

When I was writing my article about the Omega Marine that was published in the NAWCC Watch & Clock Bulletin, February 2012, I was told by the Omega museum that there was an example of a Patek Philippe Marine in the Patek Philippe museum with the same case; I have not seen it myself. Patek Philippe would not discuss this watch so it appears to have been the result of some trial work that did not lead to a series of watches.


1: OMEGA - A Journey through Time; by Marco Richon, Curator of the Omega Museum. Published 2007 by Omega Ltd., Bienne Switzerland. ISBN 978-2-9700562-2-5

2. "The Silent World", 1953. Co-authored by Captain Jacques-Yves Cousteau and Frédéric Dumas and edited by James Dugan.

Back to the top of the page.

Schmitz Freres Brev. 189190

Schmitz Freres CH 189190, 11 May 1936

A Swiss "brevet", abbreviation "Brev.", or patent No. 189190 for a waterproof case design with a distinctive "four-screw" method of retaining the case back and applying compression to a gasket between the back and the crystal was granted to Schmitz Freres in 1937, with a priority date of 11 May 1936. Reference to this patent is seen in watch cases with the legend "Brev. 189190", usually accompanied with the Swiss Federal cross Swiss Federal Cross.

The basic idea of the patent was to use four screws to clamp the back to the body of the case. To assemble a watch the case back and crystal were dropped into a recess in the case body, and the four screws were tightened down to hold the case back in place, and also to put pressure onto the joint between the case back and the crystal, making a waterproof seal. The figure from the patent reproduced here shows how this was achieved. Figure 2 is a cross section, the case back is item "a" and the crystal is item "b". There is no gasket shown between the case back and the crystal but I am sure that one would have been necessary to achieve a waterproof seal.

Tissot watch in a rectangular 189190 case
Image courtesy of Mike Benson - Holben's Fine Watches

The figure shows that the patent covered three different ways the screws could be arranged to clamp the case back. Figure 2 shows screws "f" inserted vertically, the screw head pulling the case back into place. Figure 4 shows screws "g" inserted at an angle of about 45 degrees and bearing on a notch cut in the side of the case back. Figure 6 shows screws "i" with a tapered or pointed end which enters a tapered groove on the side of the case back, the sloping contact between the end of the screw and the groove providing the clamping force. This would have been the most difficult of the three designs to manufacture, and it is no surprise that one of the other arrangements is the one that is seen.

This design of watch case was used in the Gallet Clamshell, Gallet's first water resistant chronograph. David Laurence of the Gallet Group, told me that old advertising and catalogues as well as notes taken during interviews with Bernard Gallet before he passed away showed that Gallet purchased the rights to this patent in early 1937. Manufacture of the cases began in Gallet's factory in La Chaux-de-Fonds later the same year.

An interesting detail is that Gallet had the specially flared 32.4mm crystals for the Gallet Clamshell manufactured by Germanow-Simon Machine Company in Rochester, NY, not in Europe.

At the time, Gallet's American headquarters were located in nearby Manhattan, and Gallet's waterproof watches were originally assembled in new York from Swiss components, circumventing customs duties imposed on imported Swiss watches.

Tissot watch in a rectangular 189190 case
Image courtesy of Mike Benson - Holben's Fine Watches
Gallet clamshell crystal
Gallet clamshell crystal
Copyright © The Gallet Group

Cases of this patent waterproof design were used by a number of other watch manufacturers, and the patent number 189190 appears in watch case backs. These are often referred to by collectors as clamshell cases after the Gallet original. The name was probably chosen in the same way as Hans Wilsdorf chose "Oyster" for the first waterproof Rolex watch, not because the shape resembled an oyster or a clam but as an allusion to something that was happy under water. However, "Gallet Clam" doesn't really sound quite right, so "Gallet Clamshell" was chosen, the added "shell" conveying an idea of a protective outer case, as well as being shut up clam tight. They were made in a range of sizes, and shapes round and rectangular.

The design is not as good in principle as a screw back, because the clamping force is applied to four separate points and the case back must be made sufficiently strong that adequate clamping force is applied to the gasket mid way between the clamping points. A screw back is a better solution for a round case because the pressure is applied evenly all the way around the case back joint by the screw thread.

The 189190 case design does however lend itself well to "forme" or shaped cases, which are difficult to make waterproof. The pictures here show a Tissot watch in a rectangular 189190 case with this method of sealing.

The inside of the case back reads "CHs Tissot & Fils, Brev. Swiss Federal Cross No 189190, Acier Inoxydable". The "Brev." abbreviation of Brevet and the Swiss Federal Cross always indicates a Swiss patent, sometimes one or the other is used. Acier inoxydable means, of course, steel that doesn't oxidise; usually, rather rashly in my view, called stainless steel in English

Back to the top of the page.

Concluding Remarks

By the late 1920s we have all the essential components of the modern waterproof watch - screw cases, gaskets, screw-down crowns and stem seals, some of them invented several times. There was a bit of a lull as the inventors, principally Rolex and the Tauberts, got on with making their patented designs, but once the patents came off in the 1940s, there was a veritable explosion of waterproof watch designs using these technologies.

If you have any comments or questions, please don't hesitate to get in touch via my Contact Me page.

Back to the top of the page.

Copyright © David Boettcher 2005 - 2024 all rights reserved. This page updated July 2024. W3CMVS. Back to the top of the page.