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Hans Wilsdorf and Rolex

Copyright © David Boettcher 2006 - 2020 all rights reserved.

I became interested in wristwatches, and watches in general, as a result of inheriting my grandparents' Rolex wristwatches. They were made around 1917/1918, the time of the Great War. It was through hunting for a strap suitable for my grandfather's watch that I got interested in trench watches, wristwatches worn in the trenches during the Great War, and early wristwatches in general. For this reason, most of my collection of watches and historical interest centres on the era between 1900 and 1930 and a decade or so either side.

What this page is about: In broad terms the history of the Rolex Watch Company can be divided into two parts: an early phase when they were trying lots of different ideas, and a later phase when they had hit upon a successful course. The boundary of the two phases is pretty well delineated by the Second World War, 1939 to 1945. After the war, Rolex created many iconic models of watches under a single brand, Rolex. Before the war, the situation is much less clear cut and there were attempts to create other brands that were separate from, but somehow associated, with the Rolex name. I am interested in the first phase, the creation of the Rolex brand and the pre-war history of the company, and that is what this page is about. I hope you find it interesting.

I have now moved the material about the brands other than Rolex created by Wilsdorf, e.g. Marconi, Unicorn, Tudor etc., to a new page at Rolex's Other Brands

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

The story of the Rolex watch is inextricably entwined with the story of Hans Wilsdorf, who co-founded and personally drove forward the progress of the company, and the technical developments that led to the public acceptance and expectation of an accurate, waterproof, self winding wristwatch. Many other companies and individuals contributed, and there were waterproof and self winding watches before the Rolex Oyster, but the fact remains than Wilsdorf is an important figure in the story of the modern mechanical wristwatch.

Hans Wilsdorf
Hans Wilsdorf
The four volumes of the Rolex Jubilee Vade Mecum
The four volumes of the Rolex Jubilee Vade Mecum: Click Image to Enlarge.

The picture of Hans Wilsdorf is from the Rolex Jubilee Vade Mecum published by the Rolex Watch Company in 1946. The Vade Mecum takes the form of four small booklets in a slip case shown in the smaller image, which you can click to enlarge. It was printed in a limited edition of 1,000. The booklets are:

I have copy number 619, except for volume three which is from copy number 270. All four booklets are stamped "Rolex Watch Division, C.P.O. Box 721, Tokyo, Japan" so I guess they must have all been in the same office at one time and one got switched around. If the owner of Rolex Vade Mecum number 270 reads this and wants to swap volume three, then please get in touch!

Hans Wilsdorf - Early Days

Hans Wilsdorf was born in Kulmbach, Bavaria, Franconia (Germany) on 22 March 1881, the second son of a family of three. His mother's early death was soon followed by that of his father and, in 1893 when he was 12, his uncles decided to liquidate his father's business and use the proceeds to place the children in a very good boarding school in Coburg. Wilsdorf showed a particular liking for mathematics and languages, which later drove him to travel and work in foreign countries. He apprenticed at a firm of pearl exporters whose sales organisation covered the whole world, which experience he felt was invaluable throughout his whole career.

In 1900, aged 19, Wilsdorf started work at the watch exporting firm Cuno Korten of 49 rue Léopold Robert, La Chaux-de-Fonds, Switzerland, as their English language correspondent and clerk at a monthly salary of 80 francs. Wilsdorf says that Cuno Korten was a ‘big concern’ exporting about one million francs worth of watches annually.

Outside of the long established watch making centre of Geneva, La Chaux de Fonds and Le Locle formed the hub of the Swiss Jura watchmaking industry at the time. It was a French speaking area of Switzerland so Wilsdorf would have to have spoken Swiss French in addition to his native German and English. In La Chaux-de-Fonds and the nearby Le Locle, Wilsdorf was exposed to the most influential people and companies in Swiss watchmaking, which would later be an important asset in the founding and success of his own business in London, which became the Rolex Watch Company.

Cuno Korten
Bechmann Hosted by Cuno Korten

There seems to be nothing known about Cuno Korten. The only thing I could find is the advert from 1904 reproduced here, which says that M. Bechman of the London company Baer, Bechmann & Co. Ltd. will be in Switzerland from 1 August, and that proposals of meetings can be made via Monsieur Cuno Korten of 49 rue Léopold Robert, La Chaux-de-Fonds. This was evidently a trip by Bechmann to find new lines of goods, clocks or watches, to import, and the mention of M. Korten suggests that he was facilitating meetings with Swiss manufacturers and was possibly the Swiss agent for Baer, Bechmann & Co. Ltd. Wilsdorf's English language skills would have been useful in communicating between the English and Swiss offices. Baer and Bechmann themselves would have almost certainly spoken German, but the Swiss watchmaking districts were then still mainly in the French speaking Jura and Geneva.

There is little trace of the many companies that operated in London as import agents for Swiss watch manufacturers in the late nineteenth and early twentieth centuries. Their main tasks were taking samples round to watch retailers, usually jewellers shops, and recording orders, which would be amalgamated and sent on to the watch manufacturers. There were no restrictions on the import of Swiss watches, especially after Gladstone reduced import duties in the 1860s, and before 1907 there was no requirement that gold or silver watch cases be hallmarked.

Today agents for foreign manufacturers often simply send in the orders and receive their commissions, with the manufacturer taking responsibility for delivering the goods and invoicing the customer, but in those days the agent would collect parcels of watches from the shipping agent, paying any import duties, and send the watches on the customers who had ordered them. The appearance of Baer's name in a number of bankruptcies and financial arrangements shows that agents were also responsible for collecting the money from the customer. But it was relatively easy business with little capital involved; all that was needed was an ability to speak English and Swiss French or German, an office, and a working arrangement with one or more Swiss watch manufacturers.

Bernard, or Bernhard, Baer is recorded at 52 Hatton Garden, London, in 1887, where Bechmann & Baer were later listed as clock manufacturers, although they were really importers rather than actual manufacturers. The business was converted into a limited liability company as Baer, Bechmann & Co. Ltd. at 55 Hatton Gardens on 12 March 1902.

By 1913 Baer, Bechmann & Co. Ltd. had disappeared; incorporated into Junghans Brothers Ltd., clock manufacturers, at the same 55 Hatton Gardens address. The London company Junghans Brothers Ltd. went into voluntary liquidation in 1932, no doubt a victim of the severe financial depression that followed the Wall Street crash of 1929.

Foundation of Wilsdorf & Davis

In 1903 Wilsdorf moved to London, where he said that he worked for a ‘good watchmaking firm’ which by 1946, when he wrote the Vade Mecum, had long since closed down. The name of this firm is not mentioned but it seems likely that it was one of the companies that imported Swiss watches and sold them to British retailers.

Given the connection between Cuno Korten and Baer, Bechmann & Co. Ltd. shown by the advert, it seems quite likely that Baer, Bechmann was the London company alluded to by Wilsdorf, and the date of the disappearance of that company in 1913 would fit his statement in 1946 that they had long since closed down.

Growing in confidence with the experience he gained from this and his previous employment, two years after arriving in London Wilsdorf set about establishing his own business. In May 1905 at the age of 24, he borrowed money from his sister and brother-in-law Alfred Davis, and founded the firm of Wilsdorf & Davis, 83 Hatton Gardens, London E.C.

Wilsdorf Buying Trip 1906
Wilsdorf Buying Trip 1906

In the beginning Wilsdorf & Davis did not concentrate solely, or even at all, on the top end watches that Rolex would later become known for. They imported a wide range of items that could be sold at different price points. In the Vade Mecum Wilsdorf says their first speciality was a travelling watch, called a portfolio watch, cased in fine quality leather. Wilsdorf also says that in 1905 he placed a large order for wristwatches with Aegler, a company that he had become aware of when he was working in La Chaux-de-Fonds.

The wristwatches imported from Aegler by Wilsdorf & Davis were their ‘top of the range’ items. When the name Rolex was introduced it was reserved for use on Aegler lever watches, although even these were sometimes made with only seven jewels rather than fully jewelled with 15 jewels. They also bought watches from other manufacturers, and not always of lever quality. Watches with cylinder escapement movements are seen with the W&D sponsor's mark, indicating that they were imported by Wilsdorf & Davis, although these were never branded with the Rolex name. The cylinder escapement was mass produced by the Swiss watch industry in the nineteenth century. It was cheap and robust, but inferior to the lever escapement.

The advertisement reproduced here was published in a Swiss trade journal in January 1906 and documents a buying trip to Switzerland by Wilsdorf to find stock. It says that Hans Wilsdorf is staying at the Hotel Fleur-de-Lys until the 22 or 23 of the month. Located right in the heart of La Chaux-de-Fonds, the Hotel Fleur-de-Lys is only a few feet from the train station, where no doubt Wilsdorf alighted after a train journey that began at Holborn Viaduct station in London. The advert says that Wilsdorf is especially interested in novelties for the English colonies and far-east. Not wristwatches note, or even watches at all; any novelty that might sell in the colonies or the far-east is of interest.

Wilsdorf & Davis were not watch manufacturers; they purchased watches from Swiss manufacturers and sold them on to retailers, at first with no branding at all. Then in 1907 British law changed and required that all imported gold and silver watch cases be hallmarked in a British Assay office before they were retailed in Britain. This change in the law caused Wilsdorf & Davis to register a sponsor's mark, the 'W&D' mark shown below, with the London Assay office.

Before any item could be hallmarked, the person sending it in for hallmarking has to register their details and a sponsor's mark with the assay office. Each punch used to strike the sponsor's mark onto items has to be separately registered at the assay office by striking it onto a sheet of lead or copper. This mark mark was then punched into watch cases before they were sent in for assay and hallmarking.

The registration of one's details and a sponsor's mark punch is the vital first step in the process of assay and hallmarking. If an item does not carry a recognised sponsor's mark, it will simply not be received by the assay office. When you are considering a set of marks that you think might be a hallmark, remember that there must be a sponsor's mark.


W&D Sponsor's Mark

This forced adoption in 1907 of the W&D sponsor's mark, something that also happened to look very much like a trademark, is quite possibly what started Wilsdorf thinking about branding and marketing. It is the first such mark registered by Wilsdorf & Davis, and the same mark is also seen on stamped on to watch movements, which was not required by British law.

None of the items imported by Wilsdorf and Davis before 1907 are known; they were, and still are, anonymous items with no name or branding. Because they were sold wholesale to retailers they are impossible to trace, there is not even the possibility of a point-of-sale receipt with the Wilsdorf and Davis name on it.

Wilsdorf in all likelihood thought of the items he imported as simple commodities from the import of which he could take a financial profit but no pride – they could equally well have been grain or sugar or any other commodity. But seeing watch cases stamped with the W&D mark would naturally have caused him some pride, here was some way that the goods that he dealt with would be recognised, which would create a reputation for his business. And a good reputation is valuable, something to be nurtured and cared for.

Wilsdorf and Early Wristwatches

The four volumes of the Rolex Jubilee Vade Mecum
The four volumes of the Rolex Jubilee Vade Mecum: Click Image to Enlarge.

In the Vade Mecum Wilsdorf says that he became convinced that the wristwatch was the way of the future. He thought there would be a better trade in wristwatches than pocket watches, partly because they were more prone to damage (and therefore need replacement), and partly because, unlike a pocket watch that was handed down from generation to generations, wristwatches would be fashionable items that would be personable to their wearer, who would also want to have two or three to go with different outfits. Wilsdorf was not really interested in watches from a technical point of view, he was thinking like a marketing person who wanted to generate maximum sales revenue.

In 1902 while in La Chaux de Fonds, Wilsdorf had become acquainted with the watchmaking company Aegler in Biel / Bienne, who produced a small lever escapement movement with a reputation for precise time keeping and good availability of spare parts due to the modern precision production methods, making extensive use of machinery and gauges so that parts were interchangeable.

In 1905, soon after founding his firm in London, Wilsdorf went to Bienne to see Hermann Aegler and placed the largest order for wristwatches ever seen at that time. Wilsdorf says that the first wristwatches produced under this arrangement were for men's and ladies' wear in silver cases with leather straps, and that their immediate success after the autumn launch prompted him to widen the range and introduce a selection of designs in gold cases. Evidently he got his marketing right, the success was not due to a change in fashion; ladies had been wearing fashionable wristwatches like this for nearly twenty years, since the late 1880s.

In the Vade Mecum Wilsdorf says ‘Next came the idea of expanding bracelets, which an important jewellery firm invented and launched in about 1906. This too won the approval of our British clientele ... [and] became increasingly popular throughout the Empire.’

Britannic Bracelet.
Harrop Britannic Bracelet. Click image to enlarge.
Thanks to www.historyworld.co.uk.

The important jewellery firm was Edwin Harrop, who called the expanding bracelet they invented in 1906 the ‘Britannic’ as shown in the advertisement reproduced here. Edwin Harrop was granted patent No. 24396/06 in 1907 for this design. The Britannic bracelet became extremely popular and was made for many years – at least until 1964. They are seen regularly today on ladies watches and Harrops must have sold many thousands of them.

Wilsdorf rode the success of the Britannic bracelet, remarking that ‘... both a new fashion and a great commercial success sprang from an apparently foolhardy idea. Soon we were placing orders for tens of thousands of pieces ...’ So the early success of Rolex was, in part at least, due to Harrop's Britannic bracelet.

Wilsdorf doesn't say it in the Vade Mecum, but these expanding bracelets were for ladies' wristwatches. An attempt to introduce a similar expanding bracelet branded ‘Army’ during the Great War, emphasising the benefits of a metal bracelet over leather in wet and muddy conditions, fell upon stony ground because of its effeminate appearance, despite the branding.

Very few, if any, of these early wristwatches would have been sold to men, despite what Wilsdorf says. Before the Great War, wristwatches were very much considered a woman's item and many men regarded them, like bracelets, as effeminate. An exception to this were military men who did buy wristwatches, but there is no evidence that Wilsdorf was involved in that area, or even realised that this small, specialised, demand existed.

The Britannic bracelet was guaranteed for five years, and tested in public demonstrations over 110,000 cycles. But they don't last forever, especially in everyday use, and many watches from the pre-war period have had their Britannic bracelets replaced. The lugs that attach the bracelet to the case are very narrow and won't take a leather strap, but they can be adapted for a leather strap by fitting Loop Ends.

Creation of the Rolex brand

In 1907 Hans Wilsdorf opened an office in La Chaux-de-Fonds for marketing purposes. Wishing to create his own brand he started using this Swiss office to register brand names in Switzerland. The first he name he chose to register was "Lusitania", on 1 November 1907. Lusitania was an ocean liner launched by the British Cunard Line in 1906; she was the biggest, fastest and most luxurious liner in the world at the time. In 1915 Lusitania was torpedoed and sunk by a German U-boat, an event that brought America into the Great War on the side of the Allies, but by then Wilsdorf had long since lost interest in the name.

Rolex Registration
First registration of the Rolex name in 1908

In 1908 Wilsdorf coined the name Rolex. Some have speculated that this had some complicated origin such as being derived from hoROLogie EXcellence, but in the Vade Mecum Wilsdorf says that Rolex was chosen because it was a short yet significant word, not cumbersome on the dial (thus leaving room enough for the inscription of the English trader's name) and, above all, a word easy to memorise. It has a pleasant sound and its pronunciation remains unvaried in whatever European language it is spoken. He doesn't reveal where the name came from, so we shall probably never know for sure, but it sounds like he simply made it up. His description of the way the word is short, easy to remember and pronounce echoes the words of George Eastman, who registered the trademark Kodak on 4 September 1888. Eastman said his criteria for creating the name were that it should be short, one cannot mispronounce it, and it could not resemble anything or be associated with anything but Kodak. I am sure Wilsdorf had the same considerations in mind when he devised the name Rolex.

Wilsdorf registered Rolex as a brand name in La Chaux-de-Fonds on 2 July 1908 as shown in the registration details reproduced here. This shows that Rolex is a trademark of Wilsdorf and Davis, manufacturers of watches, parts of watches and cases. Wilsdorf requested Aegler use the new trademark on all of his watches. Aegler wanted their own name to appear on the watches they manufactured, but reluctantly agreed to Wilsdorf's request. Wilsdorf wanted to create a brand that would distinguish his product from other watches, which may even have contained the same parts - Aegler was not an exclusive supplier to Wilsdorf at that time, also supplying movements to Gruen in America and others.

The Rolex Watch Company Limited was registered in London on 15 November 1915 under the Companies Acts 1908 and 1913. Today The Rolex Watch Company Limited is a wholly-owned subsidiary of Rolex Holdings SA, a company incorporated in Switzerland, and operates as part of the group's distribution and watch servicing operations. The company's principal activity is the sale of Rolex products to the watch industry in the UK and Ireland.

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Rolex in North America

Wilsdorf & Davis and Rolex started off as an English company headquartered in London. As the business expanded Wilsdorf naturally started looking to export watches to other countries. Until the Great War all Rolex watches were first imported to Britain from Switzerland and inspected in London, a practice that had been started in the eighteenth century by London retailers such as J W Benson who wished to overcome customers resistance to paying a lot of money for a Swiss watch. During the War, high import duties forced Wilsdorf to set up a Swiss office to conduct the inspection and send watches to other countries without passing through England.


Canadian A. W. C. Co. "Empress" case
Image courtesy of and © John B., 2016.

Exports of Rolex watches to other countries were successful and Wilsdorf & Davis's overseas business thrived, apart from in the United States. Rolex Rebberg watch movements were supplied by Aegler, who also supplied the company of the brothers Frederick and George Gruen in the USA. Wilsdorf and the Gruen brothers were shareholders in Aegler and had seats on the board, which resulted in the agreement that Rolex watches with Aegler movements would be sold throughout Europe, Asia and the British Empire, which included Australia and Canada, whereas Gruen would sell watches with Aegler movements in the USA only.

The image here of the inside case back of a watch with a Rolex branded Aegler Rebberg movement shows trademarks of the American Watch Case Co. of Toronto, Canada. It's a gold filled "Empress" grade case, the "10 years" is how long the plate is guaranteed to last in normal use before it wears through. The Rebberg movement would have been shipped out to Canada as a bare movement and cased there. Gold filled cases are not hallmarked so unfortunately this case can't be dated from a hallmark, but the watch appears to be from around the time of the Great War. During the War Wilsdorf had gold cases made in England, see and my immediate thought is that this case was made in Canada for similar reasons, import duties during the Great War. It is currently in England, perhaps it was brought to Europe by a Canadian soldier during the Great War and sold, swapped or lost.

Wilsdorf made a couple of half-hearted attempts to enter the US market while the agreement with Gruen was in force by selling watches with non-Aegler movements. The first was a watch with a movement from the Fontainemelon factory that was sold through Abercrombie and Fitch, a high-end retailer of sportsman's equipment and clothing. This did not work out well, the watch was not heavily advertised and had a cheap, chrome plated base metal, version of the Oyster case. Wilsdorf would not allow the name Rolex to be used on watches that didn't have Aegler movements so it was branded "Abercrombie and Fitch Seafarer", not to be confused by a later watch with the same name made for Abercrombie and Fitch by Heuer. It appears that Wilsdorf's watch didn't appeal to Abercrombie and Fitch's wealthy customers and the venture flopped.

Some time later Wilsdorf was approached by Zell Brothers, jewellers headquartered in Seattle who had a chain of jewellery stores in the North West of the USA and Canada. Zell had been selling Rolex watches very well in Canada, particularly in Vancouver which is not far from Seattle just across the US/Canadian border. The Zell brothers asked to be the exclusive importer for Rolex in the North West of the USA and Wilsdorf agreed. Again, because of the agreement with Gruen, any watches that Zell sold in the USA could not have Aegler movements. Again Wilsdorf would not allow the name Rolex to be used on watches that didn't have Aegler movements so the watches sold by Zell in the USA were branded "Turtle Timer", not exactly an inspired choice. Although the watches were better made with stainless steel case and Zell was more successful than the Abercrombie and Fitch venture, this was not a breakthrough into the US market for the Rolex brand.

In the 1930s Gruen stopped buying movements from Aegler and sold their shares in Aegler back to the family. Wilsdorf was finally free to introduce the name Rolex and watches with Aegler movements to the US market.

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Observatory Certificates

One of the areas of watch performance that Wilsdorf was very insistent on was gaining certificates of performance from independent testing establishments. These had been established in the nineteenth century to test and certify the performance of marine chronometers, and had later been expanded to test watches.

In 1914 an 11 ligne Aegler watch submitted by the Rolex Watch Company of London and Bienne to the National Physical Laboratory at Teddington, England, was tested over a period of 45 days from 1 June to 15 July, just days before the outbreak of the Great War, and was awarded a Class A Kew certificate, with an additional 77.3 marks for superior merit. This was a remarkable performance for such a small watch.

In the Vade Mecum it is said that the tests were carried out at Kew observatory, which is where watches had been tested since 1884. However, in November 1912 the watch and chronometer rating department moved from Kew to the National Physical Laboratory at Teddington, which is where the certificate was actually issued. The certificate was still referred to casually as a Kew A certificate although it carried the National Physical Laboratory name at its head.

The Vade Mecum erroneously states that the watch had undergone the same trials as “any large marine chronometer.” This is wrong. Marine box chronometers, and later deck watches, had been tested at Greenwich since 1822 for the purposes of selection by the Navy. One of the differences between the Greenwich and Kew tests was that marine box chronometers were not tested in positions, because they were suspended in gimbals which kept them dial up at all times except when they were being wound. The Kew and National Physical Laboratory watch trials could be regarded as more demanding, because they checked the performance in positions; dial up, pendant down, etc., although the timekeeping of watches was not expected to be as good as a marine box chronometer.

In 1941 the Rolex Watch Company in Bienne received a letter dated 3 October from the Swiss Bureau Officiel de Contrôle de la Marche des Montres confirming a 9¾''' chronomètre-bracelet No. 96717 had that day passed the test and become the 20,000th such Rolex watch to achieve this since June 1927.

Sponsor's Marks and Trademarks

Various marks appear on Rolex cases and movements. By tracking the evolution of these marks we can sometimes learn a bit more about the date of a watch. The earliest of these marks is the W&D mark in an oval shield with points top and bottom. This was first used as a sponsor's mark on gold and silver cases. From 1 June 1907 all gold and silver watch cases imported into Britain had to be assayed and hallmarked in a British assay office, and it was necessary for Wilsdorf and Davis to enter their details and a punch mark with the assay offices that they wished to use. This mark is also sometimes seen on watch movements. It seems likely that having created a unique mark for hallmarking purposes, Wilsdorf decided that it would also be used it to identify movements, strengthening the W&D brand identity.

The W&D sponsor's mark was superseded some time in the 1920s by "R.W.C.Ltd." The reason is not known, it perhaps indicates a more mature company stepping away from referencing the founder's names, and it also ties in with Wilsdorf's desire to promote the Rolex brand name. The R.W.C.Ltd. mark also seems to have been first used as a sponsor's mark for British hallmarking purposes, but then more widely used to promote brand identity.


W&D sponsor's mark

Wilsdorf & Davis W&D Sponsor's Mark

Until 1907 Wilsdorf & Davis imported gold and silver watches with Swiss hallmarks in their cases and under British law didn't require them to do any more. British law changed in 1907 and from 1 June 1907 all imported gold and silver watch cases were required to be assayed and hallmarked at a British assay office. Before items could be sent to an assay office for hallmarking it was necessary for a sponsor's mark to be registered. The sponsor is the person repsonsible for the item, who may not be its maker.

The sponsor's details to be registered with the assay office include a UK address and the sponsor's mark made by a punch used to identify each item that was sent in. This is the reason for the registration of the W&D sponsor's mark. The mark shown here with the initials W&D within a shield with round ends and points top and bottom was first registered at the London Assay Office on 25 June 1907. Wilsdorf and Davis were recorded in the register as importers of gold and silver wares. A second punch with the same mark was registered on 13 August 1907.


W&D on a Rebberg movement

Before watch cases could be sent to the assay office for hallmarking, the movements had to be removed and the empty cases stamped with the sponsor's mark by a registered punch. The registration of two punches on dates so close together indicates that the second punch was required to keep up with the volume of work rather than replacing a worn out punch, so Wilsdorf & Davis must have had at least two men working full time punching cases that were to be sent for hallmarking, and quite likely other workmen taking the movements out of the cases, and later putting them back into their cases after hallmarking.

The W&D mark was also entered at the Chester Assay Office on 6 April 1912. Two more punches with the same W&D mark were entered at the London Assay Office on 25 April 1915 and 25 August 1919. The same mark W&D mark was entered at the Glasgow Assay Office, but unfortunately the date is not found in the surviving records.

The following information is gleaned from Culme John Culme "The Directory of Gold and Silversmiths, Jewellers and Allied Traders, 1838-1914: From the London Assay Office Registers" Publication Date: 15 Oct 1987 | ISBN-10: 0907462464 | ISBN-13: 978-0907462460 Two volumes; the first with 4,000 biographies, the second with photographs of 15,000 marks taken directly from the London Assay Office Registers at Goldsmiths' Hall. . The partners in Wilsdorf & Davis were Hans Wilsdorf and Alfred James Davis. The address recorded at the registration of their punches was 83 Hatton Garden, later recorded on 1 November 1907 as moving to 85 Hatton Garden, EC1, then between 17 August 1912 and 25 August 1919 they are recorded at Stevenage House, 40-44 Holborn Viaduct, EC, where they are listed in 1913 as watch manufacturers and importers (TA: 'Wilsdorfs').

Wilsdorf & Davis are also recorded on 8 April 1915 at 15 Northampton Street, Birmingham, and also 3 Ruelle de la Fabrique, Bienne, Switzerland. They are recorded 25 August 1919 as having an office at 61 Rue Elfenau Gare, Bienne, Switzerland, in addition to their London office, and also as representatives of the Rolex Watch Co. Ltd. whose chairman was Hermann Aegler with Hans Wilsdorf and Alfred James Davis as directors and Harry Sedgley as secretary.

RWCLtd
R.W.C.Ltd
Image by permission © OldeTimers.com

R.W.C. Ltd.

Sometime after 1920 the W&D sponsor's mark began to be replaced by the mark "R.W.C.Ltd" in an oval shield, all incuse, as shown in the picture here. This photograph is of a Rolex Oyster case.

The marks immediately below the R.W.C.Ltd are Glasgow Assay Office import hallmarks for 9 carat gold. Reading from left to right they are a 9 on its side and ·375, the standard mark for 9 carat gold, two prone capital "F"s facing each other, the mark the Glasgow Assay Office used on imported items, and the date letter "e" for the year from July 1927 to June 1928.

The mark "R.W.C.Ltd" in an oval shield was entered as a sponsor's mark at the London Assay Office at Goldsmiths' Hall on 11 September 1923. It was also entered at the Glasgow Assay Office, although the date of its entry at Glasgow is not recorded. The earliest Glasgow hallmark that I have seen in conjunction with the R.W.C.Ltd. mark has the date letter "a" for July 1923 to June 1924, so the Glasgow registration was most likely also entered in 1923 at around the same time as in London.

There is more about these two sponsor's marks on my page about Sponsor's marks.

British and Irish hallmarks

Before 1922 all of Ireland was part of the United Kingdom, and hallmarks struck in any UK assay office were valid throughout the realm. In 1922 the Irish Free State separated from the United Kingdom and formed the republic of Ireland. As a result of this separation, Irish hallmarks were not accepted in the UK after 1923, and UK hallmarks were not accepted in Ireland after 1927. Because of this, watches imported into Britain and hallmarked in Britain, if sent to Ireland, were then also assayed and hallmarked in Dublin. This could of course happen with any British assay office mark, but Glasgow Assay Office hallmarks are the ones most commonly seen alongside Dublin hallmarks. This seems to have happened more with Rolex watches than any other, I don't know why. An example of a Rolex case marked this way can be seen at Rolex case with Glasgow and Dublin marks.

Crown or Coronet

RWCLtd
Rolex Coronet

Kathleen Pritchard says that the Rolex crown or coronet symbol with its five spikes tipped with balls or spheres was first used in an advertising campaign in 1925 and was registered later that year.

Rolex SAR

RWCLtd
Rolex SAR

The mark shown here of the letters "SAR" under a crown or coronet is sometimes seen in the case backs of Rolex watches. This mark doesn't seem to be recorded anywhere, but I suspect that it stands for "Société Anonyme Rolex". That would indicate the existence of a Swiss limited liability company or Société Anonyme (S.A.), but I haven't yet discovered the date of creation of that company.

The legend "25 World's Records" was first used in circa 1931/32 (see below for more World's Records dates).

The crown or coronet symbol above the SAR has seven spikes tipped with balls or spheres, which is two more than usually seen on the Rolex crown. I wonder why?

World's Records

Rolex case backs sometimes have a reference to a certain number of "World's Records". It is not known what records these claims refer to, but the number of records claimed increases in steps from seven to twenty and then twenty five. Knowing when the increment occurred can help to identify when a watch was made.

By studying dozens of case backs with British hallmarks, and therefore date letters that pin down the date of hallmarking to a two year period, I have identified the approximate dates when the increments of World's Records occurred. British assay offices changed their date letter punches when new wardens were elected, part way through the calendar year. At the London Assay Office this was at the end of May, for most other offices it was the beginning of July.

Parachute RM

Parachute RM
Parachute RM Trademark 1934
Image courtesy of and © John Goldberger
Robert Meylan registration 1928
Robert Meylan Registration 1928

The "Parachute RM" trademark was registered in 1934 by Robert Meylan, a Geneva based company making watch cases. They were first registered in 1928, the registration details shown here say that they specifically make wristwatch cases – boîtes de montres-bracelets. The registration also gives Ponts-de-Martel and le Chenit as if they also had operations there; I don't know what the "R.-Numa M." means. They were granted three Swiss patents for watch cases in 1932/33. There is very little recorded about the company.

One very notable thing is that Robert Meylan are not on the 1934 list of registered Swiss watch case makers Poinçons de Maître, the implication being that they didn't make watch cases of precious metals, i.e. that they only made watch cases in steel or nickel. The image of the RM parachute mark reproduced here was sent to me by John Goldberger, author of a number of books about Rolex and other brands. The mark is in the back of a case marked "Oyster Watch Co. Geneva - Swiss". It has no hallmarks of any kind and appears to be steel.

I find this rather curious. The company was first registered in 1928 when gold and silver cases were still predominant, stainless steel cases didn't come to the fore until the 1930s. Do let me know if you find a case with this mark in gold, or in any watches other than Rolex.

Thanks to John Goldberger I have now seen a Rolex case made by Robert Meylan in ·925 silver. This case doesn't carry a Poinçon de Maître. Although the system of poinçons de maître included provision for marking silver cases, very few have such marks. It was evidently only gold and platinum cases that the authorities were particularly keen to see marked.

Snowite Cases


Oyster Watch Co. Case Back: Click to enlarge.
Snowite
Snowite 20 years
Image courtesy of and © Heritage Auctions

Some Rolex Watch Co. watch cases, most them not branded as Rolex watches but with other brands such as Unicorn and Wintex, are stamped in the case back "Snowite". Some are stamped "Snowite Guaranteed to Stay Blue White". The name Snowite was registered by Hans Wilsdorf in Switzerland in February 1927.

Snowite was chrome plate over a base metal. Some people think the base metal was nickel but James Dowling told me that it was a zinc compound like Zamak or Mazak. These alloys can be formed into shapes by high pressure die casting, where the molten metal is injected into a steel mould and allowed to solidify under pressure before it is ejected. This allows a lot of identical shaped components to be produced very quickly and cheaply. The zinc alloys have a dull grey appearance and are not corrosion resistant so they are usually plated, most often with chromium.

The first commercial process for chromium plating was developed in 1924 in America and the 1927 registration of Snowite means that Rolex were one of the first companies to use it on watch cases. The 1920s economic depression that resulted in the Wall Street crash of 1929 meant that manufacturers were looking for cheaper but still eye catching alternatives to gold and silver. Stainless steel was introduced in the 1930s for the same reason

The case back in the picture here says "Snowite: Guaranteed to stay pure white for 20 years". This refers to the thickness of the plating, it won't wear through and show the base metal for at least twenty years in "normal use".

The second image shows the case back of an ‘Oyster Watch Co.’ watch made from the injection moulding zinc alloy. This is a very poor quality material and, although it is chrome plated, the back very heavily pitted on the outside. I don't have the other parts of the case so I don't know how well they survived, the case back was against the wrist and some people's perspiration can cause corrosion damage, even on some grades of stainless steel. This case is particularly bad.

Later watches with Snowite front parts to their cases have stainless steel backs to avoid this. However, even the front parts of Snowite cases can suffer from heavy corrosion. It is not a good material.

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Superbalance

Superbalance
CH196706 Patent Superbalance

Some Rolex (Aegler) watch movements have the words "Patented Superbalance" on the ratchet wheel. This refers to the type of balance shown in the image here, reproduced from Swiss patent CH196706. The patent was granted to Manufacture des Montres Rolex, Aegler Société Anonyme, Bienne (Suisse).

It is sometimes said that the purpose of recessing the screws into the rim was to make the balance more streamlined, thus reducing air resistance. This was not in fact the principal objective of the design, although one of the six claims does say that the walls of the recesses are convex in order that their shape is advantageous from an aéro-dynamique point of view. Having worked in a fluid flow laboratory I can say that the effect of this would be, at best, negligible, and that by introducing the extra turbulence-inducing walls of the recesses it might actually increase air resistance. It's a moot point. However, the main text also makes it clear that this was not the main purpose of the design.

The principal objective of the Superbalance was to make maximum use of the space available for the balance, especially within a small calibre wristwatch movement. By recessing the screws into the rim of the balance, or in effect growing the balance outwards so that it extended past the base of the screws, the radius of gyration of the balance could be made greater within a certain space than that of a balance with a plain rim and screws sticking out from that.

Inertia is the resistance of a body to any change in its speed or direction of motion. The moment of inertia, also called the rotational inertia or angular mass, determines the torque needed for angular acceleration about a rotational axis. In a watch oscillator comprised of a balance and spring, the moment of inertia plays an important role in determining the period or frequency of oscillation. The period \(T\) of oscillation of a sprung balance is given by the equation:

\[ T=2\pi\sqrt{\frac{I}{S}} \]

where \(I\) is the ‘moment of inertia’ of the balance, and \(S\) the turning force produced by the balance spring.

The moment of inertia is determined by the product of the effective rotating mass of the balance ‘m’, which as an approximation can be thought of as the mass of the rim, and the square of its radius of gyration ‘k’, which is the radial location of the effective mass and is approximately the radius of the rim as shown in red on the figure. The moment of inertia is given by:

\[ I = mk^2 \]

The Superbalance, with a radius of gyration greater than that of a plain balance which occupied the same space, could be made to have either a higher moment of inertia than a plain balance of the same mass, which would require a stronger balance spring, or a lower mass whilst maintaining the same moment of inertia. Reducing the mass of a balance whilst maintaining the same moment of inertia is beneficial because it keeps its natural frequency the same whilst reducing the loads on the balance staff pivots, which reduces friction.

The application for the patent was submitted in August 1936, but the words "Patented Superbalance" would only be used after the patent was actually granted, which was in March 1938.

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Rolex and Aegler

Aegler is very important name in the history of Rolex. From the very start of Rolex, Aegler manufactured the watches that were sold as Rolex watches. Rolex didn't own the factory that made Rolex watches, it was owned by the Aegler and Borer families. This situation continued until 2004 when Rolex bought the company.

Because Aegler is so important I have created a separate page devoted to the history of the Aegler company at Aegler.

Rolex Aegler Rebberg Movements

Aegler Rebberg movement
Aegler Rebberg Movement marked Rolex on ratchet wheel: Click to enlarge.
Aegler Rebberg movement
Aegler Rebberg Movement Marked W&D: Click to enlarge.

Aegler manufactured movements in its ébauche factory in the Rebberg district of Bienne, and consequently Rebberg was a registered as a trade mark by Aegler. Early Aegler movements used in Rolex watches are often referred to as "Rebberg" movements because of this, even if they are not stamped with the Rebberg name. If they are stamped Rebberg, it is often on the bottom plate under the dial so not normally visible.

Aegler supplied Rebberg movements to Wilsdorf & Davis, and also to a lot of other companies. In fact it is most likely that Aegler supplied complete, cased, watches. Companies in London that Aegler supplied, such as the fledgling Wilsdorf & Davis, were simple importation business operations with an office in London but no factory capability, either in Switzerland or in England to put movements into cases and test the finished watches. All the silver cases that are seen with Rebberg movements, and gold cases until 1915, were made in Switzerland, so it is clear that the movements would have been cased and the finished watches tested at the Aegler factory. You can read about the other companies that Aegler supplied on my page about Aegler and see movements with their brand names at Rebberg Movements.

The two images here show savonnette versions of these Rebberg movements with their characteristic single central bridge holding the pivots of all the train wheels; centre, third, fourth and escape wheel. The movement with the perlage decoration to the plates is 13 ligne, the one with the plain plates is slightly smaller and shows a slight variation in the shape of the central bridge, but is still unmistakably an Aegler Rebberg. They are both stem wound and set lever escapement movements with 15 jewel bearings, although Wilsdorf also imported lower grade 7 jewel versions. Savonnette movements were used in savonnette (hunter) pocket watches, and in Lépine (open face) wristwatches because they have the fourth wheel at 90 degrees from the stem. This allows the crown to be at three o'clock and the small seconds indication at six o'clock on the dial.

The smaller movement with the plain bridge is from a watch with a Borgel screw case with London Assay Office import hallmarks for sterling silver dated 1910 to 1911. Although it appears to have been made after Wilsdorf came up with the name Rolex, this watch doesn't carry the name Rolex. Both the case and the movement carry the W&D mark of Wilsdorf and Davis. On the case this is not unusual, a silver or gold case had to be punched with a sponsor's mark before it would be accepted for assay and hallmarking. But to find the same WD mark stamped on the movement is quite unusual.

The larger movement with the perlage decoration on the bridge dates from circa 1918 carries the single name “Rolex” so this is from a Rolex watch, not just a watch that was sold by the Rolex Watch Company. But notice that the Rolex brand name is engraved on the ratchet wheel. This is an easy component to change, just a single screw holds it in place. This was most likely an idea of Aegler's to reduce the amount of stock they needed to hold. They could hold ratchet wheels engraved with Rolex or any other name, and then when an order came in they could simply take unbranded movements and change the ratchet wheels to one with the name given on the order. This was a more cash efficient system than tying up lots of movements with names engraved on their bridges which then could only be sold to that customer.

Wilsdorf would have wanted the Rolex name engraved on the bridge of movement from the outset, but in the early days, before the 1920s, he was only one of many customers Aegler had and they could afford to refuse him. This is most likely the source of the story that Aegler at first refused to put the Rolex name onto their movements. They didn't want to engrave it onto the bridges because that stock could then only be sold to Rolex. But they put lots of different names on ratchet wheels, which could be easily exchanged, so it wasn't that they didn't want another company's name appearing on their movements at all, just not on the bridge where it was difficult to change or remove.

When Rolex became more important to Aegler as a customer they had to listen to him more seriously and the Rolex name got engraved on the bridge. The earliest watch that I have seen with Rolex engraved on the central bridge of the Aegler Rebberg movement had Glasgow Assay Office import hallmarks in the case back with the date letter "d" for the year 1926 to 1927.

Rolex and Dennison

Wilsdorf had the movements supplied by Aegler fitted into cases in Switzerland, or sometimes in England by the Birmingham case maker Dennison. In the beginning all watches imported by Wildorf and Davis were cased in Switzerland but during the Great War the British government imposed a high import duty on clocks and watches. This made it worthwhile to get gold cases made in Britain and Wilsdorf turned to Dennison for this. The economic incentive was not so great for silver cases because the case was a smaller proportion of the overall cost of the watch so they continued to be made in Switzerland.

Aaron Lufkin Dennison (1812-1895) had pioneered mass production watch making in the USA, but ran into technical and financial difficulties, eventually going into liquidation in a turbulent financial period in 1857. In 1871 Dennison moved to England and in 1874 set up the Dennison Watch Case Co. of Birmingham. Watch cases supplied to Wilsdorf & Davis were usually stamped "Dennison Watch Case Co." If they were silver, or more usually gold, the registered sponsor's mark for hallmarking was "ALD" for Aaron Lufkin Dennison.

Wilsdorf & Davis imported complete watches from Switzerland already cased in silver cases, and stamped these cases with their own sponsor's mark when they were sent to be hallmarked, and this was most likely true also for gold watches until the outbreak of the Great War in 1914 when high import taxes were levied on imported clocks and watches. For silver cased watches, where the case was perhaps only half the cost of the watch, it was not worth getting cases made in Britain, but it was better economically to have gold cases, which were a big part of the cost of a gold watch, made in Britain and then the movements put into them in the UK to avoid the import tax on the gold case.

There is a page about Dennison at Dennison Watch Case Company.

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Rolex on the Dial

My grandfather's Rolex wristwatch
My grandfather's 1918 silver Rolex wristwatch. No Rolex name on the dial, and there never has been. Click image to enlarge.

Early Rolex watches, by which I mean before about 1926, are often clearly marked Rolex inside the case back and on the movement ratchet wheel, as well as carrying the W&D sponsor's mark if they are in gold or silver cases with British hallmarks. These watches usually do not have the Rolex name on the dial. This is because British retailers at that time did not allow the names of foreign watch manufacturers to appear on the faces of the watches they sold. If there was a name, it was the name of the British retailer. This was usually added in enamel paint, which is not as durable as the vitreous enamel of the dial and has often partially or fully worn off.

Occasionally one finds an early Rolex watch, or even a watch that is not a Rolex, with the name Rolex on the dial, and the question is asked; is this original? Not on Rolex watches sold in Britain, for the reason explained above, and especially not on non-Rolex watches, for obvious reasons. If a pre-1926 watch with British hallmarks showing that it was retailed in Britain has Rolex on the dial, then it was applied after it left the factory - and probably quite recently. Why is this? Basically the name has been added to increase the value of the watch. The full story is, of course, more complicated than this, so read on . . .

Wilsdorf began his business in London in 1905 as an importer, ordering watches and other items from Swiss manufacturers and wholesaling these to British retailers. Until 1 June 1907 watches would have carried no signs that Wilsdorf had ever had anything to do with them. Gold and silver watches would have Swiss hallmarks inside the case back and "Swiss made" on the movement and dial.

From 1 June 1907 imported gold and silver watches were required to be assayed and hallmarked in a British assay office, so Wilsdorf had to enter his details and a sponsor's mark, the well known W&D in a shield with points top and bottom, at the London Assay Office at Goldsmiths' Hall. Imported gold and silver watch cases were stamped with this sponsor's mark before being sent for hallmarking. It could well have been this development that eventually gave Wilsdorf the idea that he could put his own brand onto watches that he ordered from manufacturers in Switzerland, causing him to create the name and brand Rolex.

This gives rise to another question that comes up quite often, is a watch that carries the W&D mark but no other marks actually an early Rolex? No, it is not. Wilsdorf was very proud of the brand name Rolex and he reserved it for the best watches. Watches sometimes turn up with the W&D mark that are not of the top grade, with cylinder escapements for instance. In the early days when Wilsdorf was getting the business off the ground he would import anything that he thought he could make a margin on, but he didn't give these the Rolex name.

Wilsdorf also created a lot of other brand names such as Unicorn, Marconi, RolCo and Tudor for lower price points, always keeping the name Rolex for the premium, top line, products. To begin with there was no secret that these were products of the Rolex Watch Company and were often marked as such, but Wilsdorf did not intend to call them "Rolex watches". It seems that initially Wilsdorf was happy if people got the impression that they were getting a Rolex watch at a lower price. But over time it was realised that this was not a good idea as it took sales away from the premium Rolex brand, and as people became more brand conscious it diluted the effects of expensive marketing that was aimed at building up the cachet of owning a Rolex, so gradually the Rolex name was disassociated from the other brands. But once an idea is planted it is very difficult to stamp it out, and today people often describe a watch with one of these other brands as a "Rolex watch". For more about these other brands see Rolex's Other Brands.

Unless a watch carries factory applied Rolex branding, then Wilsdorf wouldn't have regarded it as a Rolex, and neither should we. By factory applied Rolex branding I mean specifically the single word Rolex (Not "Rolex Watch Co.", "RWC" or any other variant) either stamped into the case back, engraved onto the ratchet wheel, or fired into the enamel of the dial.

Of course any of these can be faked, it is easy for someone to mark Rolex and W&D in a case back, engrave Rolex onto a ratchet wheel or take one from a scrap movement, and could paint the name Rolex onto the dial. I have seen many watches like this. I have even seen a Marvin watch that had been laser engraved with "Rolex" in the case back and on the movement, and had "Rolex" added to the dial with enamel paint. Needless to say, these watches have nothing to do with Rolex or the Rolex Watch Company.

Putting the name Rolex onto an enamel dial is the easiest of these to do, but it is also the easiest to detect. Because enamel paint foes not adhere well to an enamel dial, it is often flaking off, and with a touch of solvent the paint will dissolve. The same happens to retailers names painted on to enamel dials. When Rolex branding was applied to watch dials, it was fired into the enamel and impossible to remove.

British Rolex Branding

So when did Wilsdorf start applying factory Rolex branding to watch dials? In the beginning, in common with almost all other watches sold in Britain at the time, the Rolex name was stamped or engraved on the case and movement only; the dial was left free for the retailer to apply their name. To start with Rolex was a new and unknown name whilst most of the stores they supplied had been in business for a long time. Naturally people would have more faith in a watch with the name of "Asprey" or "Harrods" on the dial, rather than the unknown Rolex. This might not have been the case for markets outside Britain, of which more below

Wilsdorf had great difficulty in getting British retailers to accept the name Rolex on the dial as he explains in the Vade Mecum Despite the qualities of [the Rolex] name, it took twenty years of hard work to make the idea acceptable in England. At first, I ventured to inscribe it on one watch in every six; then it appeared on two, and later three, in every six. This half victory was still unsatisfactory and we knew that it would take many more years to obtain the desired result. Tired of waiting, in 1925, I decided to launch the "Rolex" trade mark by means of an intensive advertising campaign. The policy entailed annual expenditure of more than £12,000 - not for one year alone, but for several in succession. One of the results thus obtained was that dealers agreed first that four, and later five, out of every six watches should bear the name of "Rolex". At last, in 1927, the waterproof "Rolex-Oyster" was launched and we were then in a position to announce definitely that in future not one of our watches would ever again leave our works without our name on the dial, inside the case and on the movement.

Note that Wilsdorf says that one of the reasons he liked the name Rolex was that it was not cumbersome on the dial (thus leaving room enough for the inscription of the English trader's name) (emphasis added) and that it took twenty years of hard work to make the idea acceptable in England (emphasis added). His initial idea was clearly that the name Rolex would be placed on the dial whilst still leaving room for the English retailers name, but the retailers were not amenable. Britain and the empire was an important market for Wilsdorf and Rolex, which may be why he concentrates on this point. But is is clear that had the English retailers not prevented him from putting Rolex on the dial he would have been at it like a shot.

Wilsdorf is rather vague about what date he means when he says At first, I ventured to inscribe it on one watch in every six; He says the struggle took twenty years, and that At last, in 1927, the waterproof "Rolex-Oyster" was launched and we were then in a position to announce definitely that in future not one of our watches would ever again leave our works without our name on the dial ... Twenty years before 1927 would be 1907, when Wilsdorf had only just thought of the name Rolex. The implication of this is that right from the start one in every six British imports, which can generally be distinguished because cases at the time were usually gold or silver and carry British import hallmarks, would have had the Rolex name fired into the enamel at the factory. But I suspect that Wilsdorf is stretching the facts and that it was not actually until the 1920s that he really started on this campaign. After all, if he was so impatient and really had started in 1907 with one in six, why would he have waited until 1925 to get the proportion up to four in six? That doesn't ring true to me.

For markets other than Britain I am sure that Wilsdorf would have insisted on having Rolex on the dial from an earlier date, as did other manufacturers such as Longines and IWC, so there will Rolexes from earlier than the 1920s with the name Rolex fired into the enamel of the dial, but these would not have been officially imported into Britain and so would not carry British import hallmarks. Personal imports where someone buys a watch abroad and then returns to Britain are not required to be hallmarked. If you have a Rolex with the name fired into the enamel on the dial and a British hallmark earlier than 1925 I would be very interested to see it.

Painted Names

Dial cross section
Dial cross section

Today one sees watches carrying pre-1920 British hallmarks and with the name "Rolex" on the dial. Sometimes these are not even Rolex branded watches; Marconi and Unicorn watches end up with Rolex on the dial. Why is this done? Today people are so conditioned to seeing brand names on everything that they like to see the name on the dial. Sometimes novice collectors even think that a watch without a name on the dial is not genuine. However, adding a name to a dial is easy to do, and is no surety against forgery.

In fact, most if not all early Rolex watches with British hallmarks, and names like Marconi, Unicorn etc. on the movement but with Rolex on the dial have had the name added by the simple expedient of painting it on with enamel paint. Dealers know that this makes the watch easier to sell and gets a better price, even though they know it is not original.

Original names on enamel dials were applied while the dial was being made, fired into the enamel along with the minute tracks and hour numerals. This was easy to do while the dial was being made and the most durable. The cross section through a dial here shows how enamel dials were made. A sheet of copper cut to the correct size and shape and with holes for the hands and dial feet attached, was coated with vitreous enamel, essentially crushed glass. This was then heated in a furnace until the enamel melted, bonding to the copper and forming a smooth surface. The numerals and minute and seconds tracks were then painted on, also in vitreous enamel, and the dial fired again. This melted the enamel of the numbers and other details and bonded them to the base layer of enamel. In the cross section I have shown a white enamel dial with a red 12. When the enamel of the numbers and other details melted and bonded with the underlying enamel it became virtually flat with the dial surface as the cross section shows.

If the name to be applied was not known at the time the dial was made - such as the name of the eventual retailer, then the name was painted on later with enamel paint. The importer might have offered this as part of his service to the retailer, or the retailer may have arranged himself for his name to be painted onto the dial. Enamel paint is a totally different material from vitreous enamel, it is called enamel because it forms a harder, glossier, surface than other paints such as oil paint. However, unlike vitreous enamel, enamel paint can be dissolved by a solvent such as acetone or isopropyl alcohol.

Often a retailer's name painted on to an enamel dial has partly or almost completely worn away over the years, whereas the rest of dial markings are still crisp and sharp. This is an easy indication that the name was painted on after the watch was made. However, a name painted on recently using enamel paint can be difficult to identify, it looks crisp and sharp and glossy, just like the rest of the dial. However, there are two ways in which such an addition can be identified.

If you have a pre-1925 Rolex with an enamel dial that has the Rolex name in fired vitreous enamel, not just painted on in enamel paint which can look very similar, and the case has pre-1925 British import hallmarks, then do let me know. Of course just one example is not be proof, the dial could have been exchanged, we really need a few hundred examples . . .

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Timekeeping Precision

Wilsdorf was a perfectionist and never ceased pressing Aegler to improve the timekeeping of watches they made for him. In 1910 Aegler submitted as its manufacture a Rolex wristwatch to the Bienne testing station at the School of Horology. On March 22nd 1910 this watch received a First Class certificate and thus became the first wristwatch to be officially certified as a chronometer in Switzerland.

NB: Chronometer refers to a precision watch that is tested in various temperatures and positions, thus meeting the accuracy standards set by the official institute in Switzerland, which is only achieved by the finest quality movements. It should not be confused with Chronograph, which refers to any watch with a stopwatch function, whether the time keeping is of high accuracy or not.

On July 15th 1914, a small 11 ligne (25mm diameter) Rolex wristwatch received a Class A precision certificate from the prestigious Kew Observatory in England. This was the first time that a Kew "A" certificate had been awarded to a wristlet watch, and required that the watch pass the same tests as large marine chronometers. The watch was tested over 45 days in five different positions and three different temperatures, including ambient (65 degrees Fahrenheit), oven-hot, and refrigerator-cold. Wilsdorf said that this was a red letter day in the development of the firm, a day that he would never forget. Wilsdorf asked Aegler from then on to submit all Rolex calibres for chronometer tests. The ability of a wristwatch to maintain accurate time keeping could no longer be doubted.

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English Made Gold Cases

With the outbreak of the Great War (World War One or WW1), officers and soldiers going to the front wanted reliable and accurate wristwatches and, because they were not issued with them as standard equipment, they bought their own. Officers were given an allowance to buy their kit, uniform, sword, revolver, etc. including a wristwatch, which every officer was expected to have. This presented an opportunity for Wilsdorf to sell more wristwatches, but the war also gave rise to a serious problem for importers of watches.

Before the war London had become the export centre for Wilsdorf and Davis for overseas markets as well as Britain. Every watch was examined in London before being sent to the retailers, whether British abroad. By 1914 the London company had grown to such an extent that it was occupying a large suite of offices and had a payroll of more than 60 employees.

In 1915, as part of the war effort, the British Government imposed an ad valorem duty of 33⅓% on imported luxuries, which included clocks and watches, to conserve foreign currency reserves. This meant that any watches imported into London, even if only for checking before subsequent export abroad, would be subject to this high rate of tax.

B&S gold cased watch
English B&S gold watch case for Rolex.
Image courtesy of and © John B, August 2016.

Wilsdorf and Davis had in 1912 opened an office in the Aegler factory in Bienne to facilitate their close business relationship with Aegler. As a result of the British import duty, to avoid paying the tax on watches not destined for the British market, Wilsdorf moved his main Swiss office from La Chaux de Fonds to Bienne, and expanded the function of the consolidated office to include checking all the watches he purchased from Aegler, whether they were bound for London or elsewhere, so that watches bound for countries other than Britain did not need to pass through London. For the time being the head office of Rolex remained in London.

Watches bound for Britain continued to be made and cased in Switzerland, except for gold watches of all grades. For gold cases for watches to be sold in Britain during the period of high import duty, Wilsdorf turned to English case makers such as The Dennison Watch Case Co. in Birmingham, England, to avoid the import duty. Silver watches, which attracted less tax because of their lower price, continued to be made and cased in Switzerland.

The wartime tax started a trend of gold watch cases being made in England. In addition to Dennison, Wilsdorf also had cases made by other English makers. The image here shows a gold case made by B H Britton & Sons; Charles Henry Britton, Walter Britton and Herbert Britton, of 35 Hockley Hill, Birmingham, England. The sponsor's mark B & S was first entered at the Chester Assay Office in 1912. This shape mark was first registered in May 1931. The hallmarks in this case are Chester Assay Office marks for a nine carat gold item made in Britain. The date letter "J" is for 1959 to 1960, showing that the trend for having gold cases made in England that started in 1915 continued long after the Great War, and after the Second World War.

In 1919 Wilsdorf decided to relocate the headquarters of Rolex from London to Geneva.

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The Rise of the Rolex Brand

In Britain there was a tradition that it was the name of the retailer that appeared on watches. Wilsdorf realised that as long as the retailers continued to put their names on the dial, they had control of what they purchased and sold, because they could put their name to any watch they chose. Although by having the movement and case branded with the Rolex name Wilsdorf could build up a reputation with the retailer, this would mean nothing to the customer who would rarely if ever look inside his watch. Wilsdorf was determined to produce the best wristwatches possible, believing that this was the key to success. He also realised that he would get better orders and more control over the wholesale price of his watches if he could build up demand so that customers would go into the shop and ask for, or better still insist on, a Rolex watch by name.

In addition to the various publicity events, such as obtaining the world's first chronometer certificates for his wristwatches, Wilsdorf began to push forward the Rolex brand. Initially he applied labels to the back of the watches, but this was not enough. So from 1921 he began to ship watches with the Rolex name printed on the dial. At this time watches were shipped in small boxes, each containing 6 watches. To start with only one watch in each box had the Rolex name on the dial, then later two of them, and slowly he increased the number of Rolex branded watches sold. However, this was too slow for Wilsdorf and in 1925 he started an intensive advertising campaign costing £12,000 each year. In 1925 Rolex registered the crown symbol as a trademark. Wilsdorf writes that the retailers gradually accepted that four, and then five out of every six watches were branded Rolex.

With the launch of the waterproof Rolex Oyster in late 1926, Wilsdorf was able to insist that all Oysters should have Rolex on the dial. Wilsdorf continued his advertising campaign in support of the increasing branding of his watches, culminating on November 24, 1927 when he took over the whole of the front page of the Daily Mail, at a cost of £1,600, with a full page advert for "The marvellous Rolex wristwatch - The World's best by every test" and stated that "All Good Jewellers throughout the British Empire stock Rolex watches". By his branding and advertising campaigns, Wilsdorf effectively turned the tables on the retailers: no longer would he have to approach retailers and ask them to stock his watches, customers would demand Rolex branded watches, and the retailers would have to come to him!

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Dust and Water Resistant Cases

Being a perfectionist, attaining a class A precision certificate from Kew only spurred Wilsdorf on to addressing another shortcoming of the wrist watch: its susceptibility to dust and damp. In the wristwatch's unprotected position on the outside of the wrist, unlike a pocket watch, it was exposed to impacts, moisture, and dust. Shipments of wristwatches sent abroad were often found to have rusted by the time they arrived from exposure to dampness. Wilsdorf was not the first person to attempt to make a waterproof watch - many earlier watches are described on my page about waterproof watches - but he was by far the most commercially successful.

In the Rolex Jubilee Vade Mecum, Wilsdorf writes "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."

With the end of the first world war (WW1) in 1918, global trade resumed and Rolex found that they were sending many watches to the far reaches of the British Empire. The humid tropical climate soon rusted the movements of watches in conventional cases, so a damp proof case was urgently required. In their book "The Best of Time: Rolex Wristwatches: An Unauthorized History", Jeffrey Hess and James Dowling note that Rolex produced a small series of watches using the one piece Borgel screw case in 1922. They remark that "Despite the small number of watches produced in this case style, it is a very important development in Rolex watch design. It was the first model produced by Rolex in which the case was specifically designed to give protection against some of the elements." These Borgel screw case Rolex watches were the start of a line of development which would culminate in 1926 in the Rolex Oyster.

Borgel Cased Watch
Borgel wristwatch

Borgel Cases

In 1891 the Swiss watch case maker François Borgel (1856-1912) patented a case design where instead of having a hinged back cover allowing access to the movement, the normally separate case back and middle part were made in one piece. The movement was mounted in an externally threaded carrier ring, which is attached to the bezel and crystal, and the whole assembly screwed into the one-piece case from the front on a very fine thread. With careful manufacture and assembly the bezel could be made to screw down quite securely against the middle part of the case. The crown was held by a spring against the end of a tube carrying part of the split winding stem, creating a seal, and even the hole in the case for the push-pin for the hand setting mechanism was covered on the inside by a flat steel spring, so these Borgel cases are more waterproof than many people give them credit for. I have taken one (without its movement, just to be on the safe side) and held it under water for a few minutes and it didn't let in water. Not a dive watch maybe, but much better than the standard hinged snap back case of the time. You can read more about Borgel watches on my Borgel page.

To remove the movement of a Borgel cased watch, you first pull out spring loaded crown so that the winding stem is clear of the movement, and then the movement and bezel with the crystal unscrews out of the front of the case in one piece. Because of this, the method of setting the hands is unusual. The crown in its normal position winds the spring as usual, but obviously the pulled-out position is now used to release the movement. To allow setting of the hands, a pin just below the crown is pressed in and the crown then moves the hands. The picture shows a Borgel cased watch with the movement unscrewed from the case. You can see the screw thread on the movement, and the holes where the winding stem and pin-set engage with the movement.

Jean Finger Patent 89276
Jean Finger Patent 89276
Rolex Hermetic
Rolex Hermetic. Image by kind permission
of and © Anthony Green Antiques

The Double Case or Hermetic Watch

In January 1921 Jean Finger, a watch case maker of Longeau, Berne, Switzerland, was granted Swiss patent number CH 89276 for a " Montre à remontoire avec boitier protecteur" literally "a stem winding watch with a protective box".

This design of waterproof watch had the virtue of simplicity, in fact it was brutally simple; the watch was placed inside a larger case with a screw-down bezel which formed an hermetic seal around the watch within. To wind the watch or set the hands the outer bezel was unscrewed and the movement flipped out on a hinge allowing the hands to be set and the watch mainspring wound by a conventional unsealed crown.

Although this case achieved the desired waterproof effect, 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 the drawbacks a number of manufacturers including Zenith and Eberhard produced watches using this case design.

It appears that Wilsdorf must have liked the design and bought at least some rights to the patent, because he registered exactly the same case design in Britain on 26 May 1922, which was granted British patent number GB 197208 "Improvements in and Relating to Watches". Wilsdorf doesn't mention Jean Finger in his application, so the exact ownership of the patent is something of a mystery. An identical design had also patented by Frederic Gruen in the USA in 1918, see Double Case "Hermetic" Watches.

A Rolex "hermetic" watch using this case design was produced from 1924. Some hermetic cases bear the words " Double Boitier Brevet 89276" (Double Case Patent 89276), a reference to the Jean Finger patent. Some cases bear the initials JF showing that these were actually made by Jean Finger, but other case manufacturers such as the Borgel company of Geneva also made cases to this design.

Swing Ring or Semi Hermetic

A case design that is sometimes thought to be a variant or development of the Borgel case had a screw on front bezel and no rear opening. The movement is held in a carrier ring hinged to the case and when the bezel is removed the movement can be swung out.

This case design has been attributed to a Francis Baumgartner, but this name is an error based on the conflation of François Borgel and Frédéric Baumgartner due to their common initials of FB. The semi-hermetic case bears a strong resemblance to one patented in 1924 by Charles Rothen, an employee or associate of Borgel, which you can see on my Borgel Cases page. I have not found definitive evidence of the originator of the semi-hermetic case, it may well have been simply a development of the Rothen case.

Several companies used swing ring cases in the 1920s, including Omega, Longines and Rolex. However, they still were not sealed at the winding stem opening.

These watches are sometimes called "semi-hermetic" because of a superficial resemblance to the Hermetic watch described above, but they are not waterproof; the crown is on the outside of the case and there is no hermetic seal where the stem enters the case. In my view the name semi hermetic is erroneous and misleading, and therefore should not be used.

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The Rolex Oyster

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

In late 1926 Rolex launched on to the market a new watch with a waterproof screw-down crown and waterproof case. It was named the "Oyster" by Hans Wilsdorf, he said "because, like its namesake it could remain under water for an unlimited time without detriment."

To what extent was the Rolex Oyster an original Wilsdorf or Rolex design? There had been many previous waterproof watches reaching back as far as the mid nineteenth century, as described on my page Waterproof watches, but none of these had gone on to great commercial success. The Oyster was not the first waterproof watch, or even the first waterproof wristwatch (as was incorrectly claimed in Rolex adverts).

Wilsdorf appears to have been stimulated to create the Oyster by patent CH 114948 for a screw down crown granted to Perregaux and Perret in 1925. It would soon have been realised that the Perregaux and Perret screw crown design was essentially useless, because of the problems with the left hand thread, and it would have been Wilsdorf who cracked the whip to get the technicians at Aegler to come up with a workable design incorporating a clutch, reinventing an idea that had been patented in America in 1881.

The Oyster case was almost certainly inspired by the 1903 Borgel 3 piece screw case, the similarities are obvious and Rolex watches had been made using these Borgel cases, as well as the original Borgel patent screw case.

Although neither the crown or the case were original designs, it was probably Wilsdorf who had the idea of pulling these two ideas together and creating a waterproof watch. Why did the Rolex Oyster achieve commercial success when many earlier waterproof watches, even the war proven 1915 Tavannes Submarine wristwatch, had not?

Wilsdorf was not a watchmaker, he was a marketing genius who was prepared to invest so much on advertising the Rolex name that by the 1920s he had created a known brand from a name that didn't even exist until 1908. The previous designs of waterproof watches were created by watchmakers, and when they were not advertised and promoted they sank without trace. Hans Wilsdorf was a restless marketing genius who really propelled Rolex and the Rolex Oyster, his flagship product, towards the heights it eventually reached. He did this by spending huge amounts of money on advertising.

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The Earliest Oysters

Rolex Oyster 34303
Oyster Case Hallmarked Glasgow 1926 to 1927
Image courtesy of and © Ben Eastwood
Rolex Oyster Registration 1926
Registration of "Oyster" July 1926

The exact date that the Rolex Oyster was in the stores and available to purchase is not known. In the Vade Mecum Wilsdorf says ‘in 1927 the waterproof “Rolex-Oyster” was launched’ but there is evidence suggesting that it was on sale late in 1926. The launch referred to by Wilsdorf was probably the start of the expensive advertising campaign.

Wilsdorf acquired the patent that started his quest for a waterproof watch from Perregaux and Perret No 114948 in October 1925 and registered the name Oyster in July 1926, as shown by the extract from the Archives de l'Horlogerie shown here.

Dowling and Hess report that they have seen Rolex Oysters bearing the Glasgow Assay Office import hallmarks and the date stamp “d” for 1926/27, and an image of one such case is shown here thanks to Ben. The Glasgow year date letter was changed on July 1 every year when new wardens were elected, so Oysters carrying the Glasgow date letter “d” were hallmarked at the Glasgow assay office between 1 July 1926 and 30 June 1927.

The case back shown here is stamped with "Swiss Federal Cross114948", the Swiss Federal cross and number of the Perregaux and Perret patent, and also “Patent Applied For” above the Swiss patent number. This appears at first puzzling, because the official patent number is not known before a patent is granted and endorsed with the next number available in the patent office sequence, so this cannot refer to the Swiss patent. It must refer to a patent that had been applied for but not yet granted, which must be the next Oyster related patent, the British version of CH 114948, which has an application date of 1 September 1926 and was granted British patent number 260554 on 21 April 1927.

However, the Perregaux and Perret patent design of screw down crown, with its left handed thread, no clutch and poor sealing arrangement, was essentially useless and never used. So although the presence in an Oyster case back of the Swiss Federal cross and number 114948 with “Patent Applied For” above it could suggest a date as early as August 1926 (for the application for the British patent to be submitted on 1 September) the design of the screw crown that was actually used had not been finished at that time.

As soon as the designs of the case and the improved screw down crown with clutch had been created, Wilsdorf would have wanted to get watches onto the market. The applications for the patents would have been submitted as soon as the designs were finalised. Inventors cannot reveal their inventions to the public before a patent application is submitted, because this would allow someone to claim that the invention was not original. However, as soon as an application is received at the patent office, its date and time of submission is registered. When, and if, a patent is granted, that date becomes the “priority date” from which the period of protection of the invention runs. At the time in Switzerland that protection lasted for only fifteen years, so it was in an inventor's interest to get products into production and sold as soon as the application was in, rather than allow a whole year or more to elapse before the patent was granted.

The application for a Swiss patent on the Oyster case was submitted on 21 September 1926, and was granted as CH 120851 on 16 June 1927. Arriving at the design of the case was simpler than that of the screw down crown, it simply needed a screw back and bezel, which was well established technology. The only new feature was a thread on the pendant for the screw down crown, which a drawing in the patent shows was a right hand thread, unlike the left handed thread of the Perregaux and Perret patent. So the designers must have been working on a crown with a right handed thread.

Evidently the design of the screw down crown and clutch mechanism took a little longer. The first application for a patent on the successful design of screw down crown was lodged on 18 October 1926. This would have been within days of the design being completed and, since Oyster watches could not have been made before the design of the crown was finished, this gives the earliest date that an Oyster could have been made as early October 1926. Prototypes would have been made in great secrecy to test the design, but the first time that the successful design could be revealed to anyone outside the design team was after that all-important application had been lodged and the priority date and time recorded. Swiss patent number CH 120848 for this design was granted on 16 June 1927.

The application dates for the patents on the screw down crown mean that the successful design of screw down crown with clutch must have been arrived at in early October 1926, with the patent application drawn up and submitted on 18 October, securing the priority date although the patent would not be granted and numbered 120848 until 16 June 1927. The earliest Oyster watches with the Swiss Federal cross and number 114948 with “Patent Applied For” above it must have therefore been made between 18 October 1926, when the application was made for a patent on the successful design of the screw down crown, and 21 April 1927 when British patent number 260554 was granted, meaning that the wording Patent Applied For was no longer needed because the number of the patent was then known.

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The Screw Down Crown

The part of a watch case that is most difficult to make waterproof is where the winding stem enters the case. Some early designs of waterproof watches, such as the "explorers watches" produced for the Royal Geographical Society in the late nineteenth century overcame this problem by the simple expedient of a cap that enclosed the crown and screwed down onto the case, totally encapsulating the crown and stem, and the hole in the case where the stem entered. This was a bit of a nuisance because the cap had to be removed whenever the watch needed to be wound or set, and there was always the danger of dropping it. An alternative design that made the crown itself function as the cap was invented and patented in the United States by Ezra Fitch around 1880, but this was not a commercial success. You can read about these and other early designs of waterproof watch on my page about The evolution of the waterproof watch.

Perregaux & Perret Patent 114948
Perregaux & Perret Patent 114948

On 30 October 1925 in La Chaux de Fonds, Switzerland, Paul Perregaux and Georges Perret, registered Swiss patent No. 114948 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.

1929 Oyster Case Back
1929 Oyster Case Back
Image by permission © OldeTimers.com

When Hans Wilsdorf saw this patent, he must have thought he had found the solution he had been searching for. He bought all rights to the patent and had it assigned to him, and then applied for a British patent on 1 September 1926, which was granted as No. 260554 on 21 April 1927. He also patented it in Germany No. 443386, and the United States No. 1,661,232. You can see the Swiss and British patents referenced in the 1929 Oyster case back shown here.

Alongside the British patent number 260554 is stamped the year 1925, the year before the Swiss patent was granted, and before even an application for a British patent was lodged. This is valid because agreements between Britain and Switzerland meant that the application date of the Swiss patent was recognised as the "priority date".

However, although the Perregaux and Perret patent is often referred to as the patent that made the waterproof Oyster possible, not least by Rolex as can be seen from the Oyster case back pictured, it has some serious practical problems that prevented Wilsdorf from putting it into production.

Referring to the figure from the patent reproduced here, it can be seen that the way the Perregaux and Perret design works is as follows: the stem 4 and socket 6 are screwed together so that they are effectively one piece. The crown 8 is coupled to the stem and socket by the two screws 9 and 10 screwed into the crown. The ends of these two screws can slide in the longitudinal grooves 11 and 12 in the socket that I have highlighted in yellow. This permits the crown to move axially with respect to the stem and socket, screws 9 and 10 sliding up or down in the grooves as shown in the difference between figure 1 and figure 2.

Figure 1 shows the crown screwed down onto the case, the two screws are at the bottom of the yellow slots. Figure 2 shows the crown unscrewed from the case and now the screws are at the top of the yellow slots. The socket attached to the stem has not moved outwards with the crown as it unscrews, the two screws have just slid up the yellow slots. However, the two screws ensure that the stem and socket are locked together rotationally: the stem must follow any rotation of the crown and so while the crown is being unscrewed or screwed back down the stem has to turn.

The crown is threaded internally 15 at its lower end, and this thread engages with the thread on the tube 3 that projects from the case. The thread on the tube and the corresponding thread inside the crown are left handed.

This is quite clearly stated in the patent: "The present invention relates to improvements in keyless watches and more particularly to improvements in and connected with the winding mechanism of such watches and is concerned with improvements in that type of winder in which the winder is secured in a moisture proof manner to the pendant or equivalent by means of a left hand screw-thread on the winder engaging a left hand screw-thread on the pendant and then screwed down on the pendant compressing packing means. " (my bold emphasis)

The reason for this is as follows: when the watch needs winding the crown is unscrewed clockwise, in the direction of winding. Once the watch is fully wound, and the hands set if required, then the crown is screwed back down anti-clockwise, which the winding ratchet allows. It can't screw down in the right hand direction because the spring is fully wound, preventing any further rotation of the crown in that direction. The crown has to be screwed down in the direction allowed by the winding ratchet, which is anti-clockwise, or left handed, a very unnatural action!

There are some further undesirable consequences of this design. Once the watch is fully wound and the crown screwed down, the crown cannot be unscrewed until the watch has run down somewhat, because the action of unscrewing the crown also winds the watch, and if it is already fully wound it cannot be wound any further without breaking. So if the owner winds the watch fully, screws the crown down, and then realises that the hands need setting, he is stuck for an hour or two!


Wilsdorf Patent CH 120848

Another poor feature of this design is that the waterproof seal is formed by the base of the crown compressing the gasket 16 against the case, which is in a very exposed position, and would not have lasted long given the gasket materials available in the 1920s; leather, cork or felt.

A Better Design: CH 120848

The Perregaux and Perret design was impractical to say the least, requiring a fair amount of education and care on the part of the customer if disaster was to be avoided. Wilsdorf must have soon realised that this design was not suitable to be released to the public. He put on his thinking cap, or more likely got his "technical assistants" working on it, and by October 1926 they had come up with an improved design. The application for a patent for this was registered by Wilsdorf on 18 October 1926 and the patent was granted on 16 June 1927 as Swiss patent CH 120848, a figure from which is reproduced here.


NAWCC Bulletin, December 2010
Rolex screw down crown and its antecedents.

The clever bit of CH 120848 was that a dog clutch was incorporated into the joint between the stem and the crown, so that the crown could rotate freely while being screwed down and unscrewed from the case, but it became rotationally locked to the stem by the dog clutch when it was clear of the threaded tube on the watch case. This meant that the crown could be could be unscrewed at any time to wind the watch or set the hands, and then screwed down onto the case by a right hand thread that would be familiar to any customer.

Referring to the FIG. 1 from the patent, cylinder 6 is fixed into the crown. The base of this cylinder has a square hole 9 in it which I have ringed in red. The plug 10 screws on to the end of the winding stem, and has a circular flange 11 to centre it within the cylinder 6 and support the spring 13, and a square section 12 at its base which I have also ringed in red.

When the crown is unscrewed from the threaded tube 2, which is fixed into the case wall, it is pushed away from the case by the spring. The square section 12 on the stem end plug drops into the square hole 9 in the base of cylinder 6, and the stem and crown are then locked together rotationally as shown in FIG. 2.

As soon as the crown is pushed back towards the case to screw it down, the cylinder is pressed downwards and the square section on the stem pulls free of the square hole in the base of the cylinder. The crown is then free to rotate and can be screwed down on to the case without turning the stem.

A longer version of this history of the development of the Rolex screw down crown was published in the NAWCC Watch & Clock Bulletin in December 2010, "The Rolex Screw Down Crown and its Antecedents", as shown in the picture above.

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The Oyster Case

1929 Oyster Case Back
1929 Oyster Case Back
Image by permission © OldeTimers.com

For the Rolex Oyster a new waterproof case was designed and patented. If you look in the case back of an early Rolex Oyster such as the one pictured here you will see four patents listed: two "Great Britain Patents" 260554/1925 and 274789, and below them two "Swiss Patents" 114948 and 120851. These are a British and a Swiss patent for each of two inventions. The first British / Swiss pair (260554 / 114948) were for the waterproof screw down crown; the second pair (274789 / 120851) were for the waterproof Oyster case.

The Oyster case was made waterproof by having a screw back and bezel, and the screw down crown. How the glass was made waterproof in the bezel is not described, but presumably it was simply made a tight fit. The Oyster was not intended to be a dive watch!

An interesting feature of the patent for the case is that it begins by saying that the invention refers to a shaped or "forme" watch case (i.e., different from the usual round or circular form). The patent goes on to illustrate and describe an octagonal case and the means by which such a case can be made watertight. The only reason that I can think of for making the case octagonal shape is to make it more difficult to seal than a round case, and therefore to have something to patent.

Referring to the cross section below, the movement is held in an externally threaded carrier ring 5, which passes through the centre of the shaped case. The front bezel and case back, both numbered 11 in the drawing, screw onto the external threads of this carrier ring, rotating in opposite directions and clamping the middle part of the case between them to form the water tight seal.

Oyster case cross section
Oyster Case Cross Section

The design of the threaded carrier ring is so reminiscent of the screw cases designed by François Borgel that it is not surprising that many people think the Borgel company, then owned by the Taubert family, must have been involved in the design, but no link has yet been proven. In their book on Rolex, Dowling and Hess note that Rolex produced a small series of watches using the original one-piece Borgel screw case in 1922. In fact, the relationship between Borgel and Rolex goes back to way before the 1922 date mentioned by Dowling and Hess. The image here shows a Borgel case with London import hallmarks for 1910 and the W&D sponsor's mark entered by Wilsdorf and Davis.

Borgel case back
Borgel case with London hallmarks for 1910 and W&D mark

The Borgel company also supplied Rolex with three piece 1903 Borgel patent screw cases in the 1920s. The Oyster case was virtually identical to the earlier Borgel design and it seems obvious that the Oyster case was based on the 1903 Borgel design. The question is, why weren't the Oyster cases made by the Borgel company, then in the ownership of the Taubert family?

Wilsdorf was working on the Rolex Oyster in the years before it was revealed in 1926, and the Borgel company was taken over by the Taubert family in 1924, so perhaps Wilsdorf didn't want to approach what was essentially a new company. The Tauberts would also most likely have insisted that their Borgel trademark of the initials FB over a Geneva key to appear in any cases they made, which wouldn't have suited Wilsdorf.

The threaded Oyster case backs were milled with small radial grooves like the edge of a coin to provide the grip needed to tighten and release them by hand, the same as François Borgel had been using on the bezels of his screw cases since 1891. To get a tighter seal than possible by hand tightening in 1926 Wilsdorf designed a tool that engaged with the millings and enabled greater torque to be applied than by hand. On 3 October 1929 Wilsdorf applied for a patent for this tool, which was published on 16 January 1931 under N° CH 143449. The millings on the case backs of modern Rolex watches, and the case openers used today, derive from these early designs.

In the first Oyster case the screw thread on the pendant was cut into a pendant that was made as part of the middle section of the case. If the case was gold or silver, as the vast majority of watch cases were in the 1920s, the threads in these soft metals wore very quickly as the crown was unscrewed every day to wind the watch. This was overcome to a degree by making the pendant a separate steel tube that was harder wearing, and could be replaced if necessary. The problem of thread wear was only really overcome when automatic winding was introduced, which dramatically reduced the number of times that the crown needed to be unscrewed.

Oyster Patents

Oyster cases accumulated a series of patent numbers inside their backs over the years as listed below. If you know of one I have missed, please let me know. Later models simply had “Patented in all Countries” rather than the long list, perhaps to save on the cost of engraving, or because there wasn't room to fit them all in!

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Who Made the Oyster Cases?

Glasgow 1927 to 1928 RWCLtd
RWCLtd, hallmarks Glasgow 1927/28
PdM
PdM No. 1 with number 136

Rolex do not reveal information such as the identity of the case maker who supplied the cases for the first Rolex Oysters. However, beginning in the mid 1920s Swiss watch cases of gold and platinum had to be marked to identify the case maker. These marks, called Poinçons de Maître, were very small, and the identity of the maker was encoded, so they are not well known. I am not going to go into this in detail here, you can find more about it on my page about Swiss Poinçons de Maître, but the important point is that these marks can in principle be read to identify the maker of a watch case. The problem is that they are so small they usually can't be read from photographs, at least not at the resolution commonly published on the internet.

Thanks to Crispin at Oldetimers.com I was able to examine nine high resolution pictures of early Oyster cases. From these I was able to date the cases from the date letter of the British import hallmarks, all impressed by the Glasgow Assay Office, and to read the symbols and numbers of the Poinçons de Maître (PdM). Since then I have also seen a case with Glasgow Assay Office import hallmarks and the date letter "d" for the year 1926 to 1927. All the cases bore the sponsor's mark of "R.W.C.Ltd" inside an oval shield, both the letters and shield being incuse, that is impressed into the plate rather than being in relief or cameo.

The image shows a typical Glasgow Assay Office import hallmark for 1927 to 1928. Reading from the top there is the sponsor's mark R.W.C.Ltd which shows who or what company submitted the item for hallmarking, then below that the sideways "9" and "·375" standard mark for nine carat gold, Glasgow Assay Office town mark for imports of two prone and opposed "F"s and finally the date letter "e" for 1927 to 1928. Date letter punches, properly called the “assayer's mark”, show who was responsible for the assay and therefore were changed each year when new Wardens were elected. This was part way through the calendar year, so a hallmark date letter refers to parts of two years. For brevity most tables of hallmark date letters show only the first year in which the date letter punch was used. The Glasgow date letter was changed on 1 July each year, so a case with a Glasgow Assay Office date letter “d” was marked between July 1926 and June 1927. There is more about this type of mark on my page at British import hallmarks.

Oyster case hallmarks
All hallmarks Glasgow Assay Office
Date
letter
YearPdM
d1926/27136
e1927/28136
e1927/28136
f1928/29136
h1930/31136
k1933/34136
l1934/35136
m1935/36136
n1936/37136
o1937/3810
transfer of patent 114948
Transfer of patent 114948

The hallmarks cover a ten year period from July 1926 to June 1937 and all the cases, except the last, have the Poinçon de Maître of a hammer head bearing the number 136. This shows that they were made by the company of C. R. Spillmann SA of La Chaux de Fonds, later Chêne-Bourg and this shows that C. R. Spillmann SA were the makers of the first Rolex Oyster cases.

The company C.R. Spillmann was involved in the acquisition by Wilsdorf and Rolex of the rights to the Perregaux and Perret patent for the screw crown, CH 114948.

The record from La Fédération Horlogère Suisse shown here records the transfer in October 1925 of the rights to the Perregaux and Perret patent CH 114948, first to C.R. Spillmann et Cie,, and then onwards from Spillmann to Hans Wilsdorf. Together with the Poinçons de Maître from the Oyster cases dating back to 1927 this shows that the Spillmann company not only made the waterproof cases of the first Rolex Oysters but was heavily involved in the design of, and in fact probably were the actual designers of, the waterproof case.

PdM2
PdM No.2 with number 136

The PdM No. 2 mark of a hammer with handle and the number 136 shown here is in the case of a Rolex Oyster with Glasgow Assay Office import hallmarks for nine carat gold, the date letter "d" for 1926/27. This is interesting because the vast majority of early Rolex Oyster cases that I have seen have PdM No.1, the hammer head. The registrant of PdM No. 2, the hammer with handle, with the number 136 is not recorded in the 1934 list, but given the registration of PdM No. with number 136 to C.R. Spillmann S.A., I think it is safe to say that PdM No. 2 the hammer with handle No. 136 must also have been registered to C.R. Spillmann SA.

In later years C. R. Spillmann S.A. specialised in cases for chronographs, making the cases for all of the early Omega Speedmasters and most of the Rolex Daytonas, until Rolex bought the Spillmann company to bring case production “in house”. Thanks to James Dowling for this information.

The company of C.R. Spillmann SA were listed as makers of gold watch case in La Chaux de Fonds. An obituary in La Fédération Horlogère Suisse recorded that Charles-Rodolphe Spillmann died on September 7th 1938. He was the founder and managing director of the company. He was also a founder and member of the executive committee of the Society of Swiss watch case manufacturers. The address given in Spillmann's obituary was La Chaux-de-Fonds, but the 1934 list of PdM gives the company address as Chêne-Bourg. I think that the company of C.R. Spillmann had its headquarters registered in La Chaux-de-Fonds, the building is still there listed as a Swiss heritage site of national significance, with a factory in Chêne-Bourg.

The CR Spillmann SA Poinçon de Maître was cancelled on 5 April 1988, presumably as a result of the takeover of the company by Rolex.

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Oyster Case Serial Numbers


Oyster CaseSerial Numbers: Click to enlarge.

When I started to examine early Oyster cases in detail, the serial numbers seemed to follow no pattern at all and appeared to be completely random, which I mentioned on this page. James Dowling recently remarked to me “I disagree with you about the Oyster case numbers, I very firmly believe that they are sequential.” So I went back to the data and had another look, and an interesting pattern appeared.

I plotted the data from a number of cases to produce the chart shown here. The dates of the cases are taken from their British hallmarks, and it must be remembered that hallmark date letters span two calendar years. For the Glasgow Assay Office, where most of the cases were hallmarked, this was from 1 July to 30 June. The dates I used for this chart are the first year in which the case could have been hallmarked. Also, a hallmark date letter shows only when the case was hallmarked, not when the case was finished after it had been hallmarked and fitted with a movement to make it into a watch.

When looking afresh at the data again, I noticed that the reason for the apparent randomness is that the gold and silver cases appear to have completely different series of serial numbers. In the plot here I have separated out the gold and silver, and it can be seen that their serial numbers do show consistent trends (if I exclude three “outliers” shown in blue).

The silver cases, plotted in yellow, have lower serial numbers than the gold cases, plotted in red. It appears that the silver case serial numbers might have started at zero and the gold cases at 20,000. There are linear regressions lines plotted for the gold and silver case data. Their associated equations have slopes of 3316 for gold cases and 3771 for silver, which suggest approximate annual production rates. Because so few watches with gold cases of any make survive from this period in comparison to those with silver cases, it is natural to assume that watches with silver cases were made in larger numbers, but in fact production data from Swiss case makers shows that gold and silver cases were made in similar numbers. It is the intrinsic value of gold that has led to the loss of many gold cases to the bullion refiner's melting pot over the years.

There is a table of Oyster case serial numbers in the back of the Dowling and Hess Rolex book, also based on hallmark dates but whether the cases were gold or silver is not recorded. I plotted on the chart the data from the book up to 1939, which appears in green. The resulting plot is quite interesting - certainly the general trends are in the same direction. The green line is not a regression line, it simply joins the dots. It shows a notable flattening between 1930 and 1934, reflecting slow sales of expensive watches due to the economic recession that followed the Wall Street crash of 1929.

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Oyster Movements

Aegler Rebberg movement
Unusual Rebberg marked Rolex on Ratchet Wheel: Click to enlarge.
Thanks to Tim N. for the image.
Aegler Rebberg movement
Typical Rebberg Movement marked Rolex on Ratchet Wheel: Click to enlarge.

The movements or ébauches for Rolex Oyster watches were made by Aegler at their factory in the Rebberg district of Bienne, because of which they are called “Rebberg” movements.

The first image here shows a typical Aegler Rebberg movement marked Rolex on the ratchet wheel. The centre bridge is a very distinct shape and makes these movements easy to identify. Putting all the train wheel bearings into one plate makes the movement more difficult to assemble than one with separate cocks, but is more rigid and dimensionally secure. This was the standard movement used in most Rolex watches, including most manually wound Oysters.

The second image shows an unusual Aegler Rebberg movement marked Rolex on the ratchet wheel. This movement was used in small numbers of Rolex watches, including Oysters, for a few years in the mid 1920s. The most obvious difference is the sweeping curved centre bridge, but the setting lever screw is also in a different position indicating that the keyless mechanism is different from the standard Rebberg model.

The keyless work of this movement was the subject of Swiss patent N° 97101, application date 2 August 1921 granted 1 December 1922. The subject of the patent is the winding mechanism crown wheel, the smaller of the two winding wheels which is turned by the winding pinion on the stem during winding. In the patented design the crown wheel is held onto the bridge of the movement by means of a fixed central core that is attached to the bridge by two screws. This is an improvement over the usual method of securing the crown wheel to the bridge by a single central screw, which usually has a left hand thread so that it does not unscrew during winding. This was not an original invention; crown wheels with fixed central cores like this were made in the nineteenth century so I am surprised that a patent was granted.

Movements were graded Prima, Extra Prima and Ultra Prima. There is no visible difference between the three grades of movement, they were graded after they were finished on the results of timekeeping tests and the ratchet wheel exchanged for one with the appropriate engraving.

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Advertising Oysters

Once he had a fully waterproof wristwatch in the Rolex Oyster, Wilsdorf was determined to promote it in any way possible and embarked on an extensive and expensive advertising campaign.

On 7 October 1927, Mercedes Gleitze became, at her eighth attempt, the first British woman to swim the channel. She swam from France to England in 15 hours and 15 minutes. Because of a hoax claim (which was soon proven to be false) by Dr. Dorothy Cochrane Logan (using her professional name, Mona McLennan), to have swum the Channel on October 11th in the faster time of thirteen hours and ten minutes, Gleitze's own claim was cast into doubt. To silence the doubters, Gleitze decided to repeat her feat in what became known as "the vindication swim".

Mercedes Gleitze
Mercedes Gleitze

Recognizing a tremendous opportunity to demonstrate the durability of his "Oyster" watch, Wilsdorf offered a new Rolex Oyster watch to Miss Gleitze if she would carry the watch during her swim, to which she agreed. Although it has often been said that she wore the watch "strapped to her wrist", in fact she wore it on a ribbon around her neck. On 21 October at 4:21am Mercedes Gleitze once again entered the water at Cap Gris Nez. But this time the water was much colder, and she was unable to complete the crossing. At 2:45pm, after swimming for 10 hours and 24 minutes, she was pulled semi-conscious from the water some seven miles short of the English shore.

Gleitze Channel Swim
The Times, Oct 22, 1927

Although she did not complete the second crossing, a journalist for The Times of London wrote "Having regard to the general conditions, the endurance of Miss Gleitze surprised the doctors, journalists, and experts who were present, for it seemed unlikely that she would be able to withstand the cold for so long. It was a good performance." This silenced the doubters, and Mercedes Gleitze was hailed as a heroine.

As she sat in the boat, The Times' journalist made a discovery and reported it as follows: "Hanging round her neck by a ribbon on this swim, Miss Gleitze carried a small gold watch, which was found this evening to have kept good time throughout." When examined closely, the Oyster watch was found to be in perfect condition, dry inside and ticking away as if nothing had happened.

1930 Punch Advert
1930 Rolex advert in Punch

One month later, on 24th November 1927, Wilsdorf launched the Rolex Oyster watch in the United Kingdom as the focal point of a full front page Rolex advert in the Daily Mail, and the Rolex Oyster began its rise to fame.

Old Bond Street House
6-8, Old Bond Street
London, W.1.
13th May 1930

Dear Sirs.

I have now been using my Rolex Watch for some little while, and it is keeping perfect time under somewhat strenuous conditions.

I was wearing it on the occasion of the J.C.C. Double 12 Hours Race on Friday and Saturday last, and the vibration which this watch had to withstand during this long period has not upset its time-keeping properties in the least.

I would like to congratulate you on having produced a very first-class Watch, suitable for really rough treatment.

Yours faithfully, Malcolm Campbell

Wilsdorf also co-opted various sporting personalities into endorsing the Oyster. This advert appeared in Punch on the 18 June 1930. In it is reproduced a letter from Captain Malcolm Campbell (he was knighted as Sir Malcolm Campbell in 1931).

Note that although Campbell says that the watch is suitable for really rough treatment this was still before the widespread use of shock protection jewel settings for the balance staff pivots, so a sharp blow could, and still can, break the balance staff pivots on one of these watches, so don't take Campbell too literally.

In another marketing coup, in 1935 a Rolex Oyster went over 300 miles per hour on the wrist of Sir Malcolm Campbell as he set the world land-speed record in his race car at Salt Lake Flats.

The investment of a watch in Miss Gleitze's attempt proved a typically shrewd move by Wilsdorf, and Rolex were still using the event in adverts into the 1950s. The advert below left from Punch in August 1950 states that the Rolex Oyster was the first waterproof wristwatch in the world, which is not strictly true, there were other waterproof wristwatches made before the Rolex Oyster, but it was the first that was advertised to a mass audience through an extensive advertising campaign, Wilsdorf's forté.

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The Rolex Perpetual

Now that the problem of water-proofing had been solved, there was just one small remaining issue; namely, that the owner had to unscrew the crown each day in order to wind the watch. There were two side effects of this; (1) sooner or later the owner would forget to screw the crown down tightly again and the watch would no longer be hermetically sealed, and (2) in time the waterproof seals or the threads would wear out. Wear of the threads on the outside of the stem tube that the crown screwed down onto was a serious problem with manually wound Oysters. Many have had the stem tube repaired or replaced. Initially the stem tube was made of of the same material as the case, gold or silver, which are both quite soft metals that wore very quickly. A threaded steel tube was soon designed that inserted into the case in place of the integral stem tube and lasted longer.

These problems were finally solved by Rolex in 1931 with the introduction of the “Perpetual” self-winding movement.

The concept of a self-winding watch had first been introduced in 1770s. For many years it was generally believed that the rotor self winding mechanism was invented by the Swiss watchmaker Abraham-Louis Perrelet, but information uncovered by Richards Watkins includes a report from 1778 that is a clear indication that it was Hubert Sarton, of Liège in Belgium, who invented the rotor wound watch.

However, Perrelet independently designed a self-winding watch at the end of 1775 or at the beginning of 1776. The winding mechanism worked on the same principle as a pedometer, using an reciprocating weight inside the watch that moved up and down as the owner walked, which through a set of gears wound the mainspring. Perrelet was the first person to create a working, practical mechanism.

The Parisian clock and watchmaker Abraham-Louis Bréguet improved the mechanism in his own version, calling his watches "perpetuelles"; the French word for perpetual, and possibly the source of Rolex's name for its "Perpetual" automatic or self winding movements.

1950 Punch Advert
1950 Rolex Advert in Punch

The first self winding wristwatch was invented in 1923 by a watch repairer from the Isle of Man named John Harwood. He took out a UK patent with his financial backer, Harry Cutts from Cheshire, on 7 July 1923, and a corresponding Swiss patent on 16 October 1923. The Harwood system used a semi circular weight that pivoted at the centre of the movement and swung through a 300 degree arc as the wearer moved his wrist or arm, and through a train of gears wound the mainspring. This was called a "bumper" design because the weight ran into a spring bumper at the end of its 300 degree travel, which the wearer could feel. When fully wound, the watch would run for 12 hours. It did not have a conventional stem winder, so the hands were moved manually by rotating a bezel around the face of the watch.

Harwood formed the Harwood Self-Winding Watch Company and commissioned the Swiss firms Fortis and A. Schild to make the watches using the Adolf Schild Calibre Cal. 350 as the base movement. The watches went on sale in 1928. They were not a runaway success in the market, and only some 30,000 were made in total. However, the presence of the patent meant that from 1923 no one else could develop a similar or improved version, so progress was essentially halted at a time when the wristwatch was becoming more and more popular. The Harwood company collapsed in 1931 during the Great Depression and, although the patent still existed, there was no one to exercise it so other companies were free to develop their own versions.

Emile Borer, nephew and ultimately successor to Hermann Aegler and head of research and development at the Aegler Bienne factory, took up the Harwood design and used it as the basis for a self winding mechanism. He improved on Harwood's design so that the centrally mounted semi-circular weight became a rotor which could rotate smoothly through a full 360 degrees and was able to turn both clockwise and counter clockwise, rather than running the 300 degrees and then hitting the bumpers of the Harwood design. This improved its performance, durability, and feel for the wearer, although it only actually wound in one direction. The amount of energy stored in the mainspring was increased, allowing the watch to run autonomously for up to 35 hours. Felsa introduced the patented 410 calibre "Bidynator" (bi-directional winding) in 1942; Aegler did not produce a bi-directional automatic winding movement until 1950 with the calibre 1030.

As a result of automatic winding it was no longer necessary to manually wind the watch every day, and the crown was used principally to set the time. As this did not require doing often, due to the accuracy of the watch, the waterproof seal was only disturbed occasionally and there was much less wear in the threads or likelihood of forgetting to screw the crown down. Consequently, Rolex Oyster Perpetual watches were now not only accurate but also durable. The automatically wound watch was even more accurate than the hand wound version because the tension put on the mainspring by constant automatic winding whilst the watch was worn was more even than that provided by winding once a day.

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Copyright © David Boettcher 2006 - 2020 all rights reserved. This page updated October 2020. W3CMVS. Back to the top of the page.