Aegler
Copyright © David Boettcher 2005 - 2023 all rights reserved.The Aegler watchmaking company was established in Biel / Bienne in 1878 by Jean (English: John) Aegler.
Biel / Bienne is on the language boundary between the French and German speaking parts of Switzerland, hence the dual name for the town. Biel is German, Bienne its French counterpart. Because Biel / Bienne is a bit of a mouthful, I shall refer to the town simply by its French name of Bienne.
Jean Aegler was born on 25 January 1850 in Krattigen, a small Swiss village about 90 kilometres south east of Bienne situated on a hill overlooking Lake Thun. He was the son of Johannes Aegler and Susanna nee Isler. In the 1882 Lehrerbestätigungen or teacher confirmations for Bern, Johannes Aegler von Krattigen is recorded as being a teacher at the upper middle school of Schüpfen, a municipality in the canton of Bern about half way between Bern and Bienne. Johannes is also said to have been an “instructeur, huissier et facteur”, so perhaps he dabbled in commerce as well as teaching.
Jean Aegler trained as a watchmaker before founding his own company. Jean married Anna Maria Ramser of Krattigen on 26 July 1873 in La Neuveville, a town on lake Bienne. From this, and the fact that Jean founded his company in Bienne, it seems likely that Jean was sent to Bienne for his watchmaking apprenticeship.
In 1881 Jean Aegler acquired a workshop in the Rebberg-Vignoble district of Bienne at 80 La Haute-Route (the High Way, Höheweg in German) overlooking the city centre. In German the word Rebberg means vineyard, the same as the French vignoble, so presumably in earlier times this had been a grape growing and wine making area of Bienne.

Aegler Ownership 1883
It seems Jean had help from his father in this enterprise, because the Swiss Principal Register of Commercial Interests records a declaration dated 24 March 1883, shown in the image here, that the owner (inhaber) of the J Aegler company in Biel is Herr Johannes Aegler von Krattigen. The nature of the business (natur des geschäfts) is stated as “Chef d'atelier für Uhrenfabrikation zum Rebberg, in Biel.” This mixture of French and German translates literally as Workshop chief for watch manufacture in Rebberg, Biel. The early history of this factory is virtually unknown.

Aegler Trademark Registration 1885: “Fabricant Montres”
Jean Aegler probably did not start making complete ébauches in 1881, because it would have taken him time to accumulate the capital to buy the necessary machinery, work out the designs for the movements, recruit and train workers etc., so he most likely started out either making or finishing component parts for other companies, gradually building up his factory and workforce until he had the capability to produce the complete movements.
It is not known when Johannes Aegler became no longer part of the company, but this was probably signalled by Jean Aegler registering his own trademark. On 10 September 1885, at a quarter past 12, Jean Aegler, fabricant (manufacturer), registered the trademark shown in the image here, which looks like a stylised script form of a capital letter A. The trademark was unequivocally for a “Fabricant” or manufacturer of “Montres.” There is no quibbling here; this was not a trademark for parts of watches, or bits and pieces and attachments, this was a trademark of a manufacturer of watches.
In 1886 Jean Aegler was present at a meeting of horological workers of Bienne and the surrounding area at which the formation of a syndicate to control prices and working conditions in the industry was agreed. Aegler was named in a list of workers who specialised in “small pieces.” In view of the 1885 trademark registration and Aegler's later reputation for making small watches, it seems likely that this refers to small movements rather than small component parts. This view is supported by a letter of 1888 announcing the formation of the Syndicat de fabricants d'horlogerie. Jean Aegler was one of the signatories to the letter as secretary to the syndicate.
Jean Aegler died on 2 August 1891 in Bienne at the young age of only 41 years. In Switzerland, privately owned companies had to be named after the person or persons in charge, so as soon as one person or partner died or left the company, a name change had to follow. In this case the name was changed Veuve Jean Aegler, (widow of Jean Aegler), in German Witwe Jean Aegler, often abbreviated to Vve Jean Aegler as in the image or or Wwe. This device maintained continuity of the Jean Aegler name whilst complying with Swiss company law.
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Aegler Factory
The advertising image here of the first Aegler factory shows in the top right corner a picture of a three storey building with the legend “Fabrique d'Horlogerie” along the front and “Jean Aegler” at the side beneath the top floor windows.
The image shows the first factory block from 1881, although the image was obviously made after Jean Aegler died in 1891 and his widow had taken over running the company because the central bar says “Vve. Jean Aegler (Widow of Jean Aegler).
A couple things in the image are worth noting. It says that the company specialises in Damen-Uhren or Montres Pour Dames; German and French terms for ladies' watches. These were small pocket watches or fob watches, worn pinned to the outside of clothing on a fob or chatelaine. The movements of such watches are the perfect size to make men's wristwatches, something that became important later in Aegler's history when Hans Wilsdorf, the founder of Rolex, began placing large orders with Aegler for wristwatches.
Wilsdorf said that Aegler specialised in lever escapement movements, which has led some to assume that Aegler didn't make movements with cylinder escapements. However, the Calibre Special shown in the image, shown more clearly in the separate image which has been extracted from the advert and cleaned, clearly has a cylinder escapement – the cock beneath the balance is for the escape wheel which, in a cylinder escapement, has to be planted next to the balance because there is no intermediate lever. The train bearings are jewelled, with the jewels set in chatons.
The second thing of note in the advertising image is the diamond shape at bottom right with the Swiss Federal cross and SP and 243. This is a reference to Swiss patent No. 243 for a keyless stem winding and setting mechanism. The movement in the advert labelled Calibre Special clearly has keyless winding, the crown and ratchet wheels are visible in the Swiss fashion.
An Aegler Calibre Special movement stamped with the patent reference SP 243 can be seen in the image here kindly supplied by Piers of the movement of a watch in his possession. This is clearly the same as the Calibre Special illustrated in the Aegler advertisement, the shape of the barrel bridge which also holds the bearings for the centre, third and fourth wheels, is identical. The drawing in the advert is so accurate that it was most likely taken directly from a finished movement, the only differences are that the movement in the drawing does not have its dial feet securing screws and the jewels for the third and fourth wheels are set in chatons rather the being pressed in.
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Aegler Patent No. 243
On 15 November 1888 Jean Aegler was granted Swiss patent No. 243 for a Mécanisme de mise à l'heure par la couronne; a mechanism for setting the hands to the correct time using the crown. This patent is referenced at the bottom of the advert: "Brevet pris on Suisse sous No. 243" – Swiss patent is taken under No. 243.
This keyless mechanism, so called because it enables the watch mainspring to be wound without using a key, was a variation on the sliding sleeve mechanism invented by Adrien Philippe in 1845. In common with many patents taken out on stem winding and setting mechanisms based on Philippe's invention, Aegler's patent concerned the arrangement of levers that moved the sliding pinion between the winding and setting positions.

Figure from Aegler patent 243 of 1888

Transfer of Patents to New Partnership
In the figure from the patent you can see the Philippe winding and setting pinions clearly, the crown or winding pinion is labelled C, the sliding pinion B. Pulling upwards on the stem causes lever F to press down on lever A, which is engaged in the slot around the sliding pinion. Lever A rotates around its securing screw as shown by the dotted lines and the sliding pinion is pressed downwards into the hand setting position. When the stem is pushed down, the spring a pushes the lever A back, which returns the sliding pinion to the winding position.
When Jean Aegler died 1891 his widow Anna Maria took over the business, which was renamed in French Veuve Jean Aegler (widow of Jean Aegler), often abbreviated to Vve. Jean Aegler. In German it was Witwe Jean Aegler, Witwe meaning widow in German, often abbreviated to Wwe.
An additional patent No. 243/104, an extension to No. 243, was granted to Madame Veuve Jean Aegler in December 1891. This patent, with the same title as the original 243, was for an improvement to the mechanism of levers that moved the sliding pinion between the winding and setting positions. The difference is very small, only slight changes to the shapes of the levers. Today this would not be accepted as a new "invention". Swiss patent law had only been introduced in 1888 and in the first years many designs that would not have been patentable in Britain or the USA were granted patents in Switzerland. Swiss manufacturers evidently saw it as a good way to both protect their designs and gain a bit of status by stamping patent numbers, or references to patents with the word Brevet or the symbol of the Swiss Federal cross
, on their products.
By 1902 the business, under the direction of Hermann and Hans Aegler, the sons of Jean and Anna Maria, was manufacturing small ébauches with lever escapements. The business gained a reputation for the mechanised manufacture at reasonable prices of good quality lever movements on the gauged and interchangeable system of mass production.
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Aegler Manufactures Ébauches

Aegler Advert from 1890
A press release by Rolex announcing a new Rolex factory in Bienne in 2012 said that the Aegler factory began to produce its own ébauches between 1890 and 1895. However, it seems likely that Aegler was making complete movements from some time before then.
The Aegler advert from 1890 reproduced here says that the “fabrique d'horlogerie” (watch factory) Jean Aegler of Rebberg, Bienne, specialises in stem wound watches (remontoirs au pendant) and has a new system of setting the time, the most advanced that exists (le plus perfectionné qui existe).
The stem wind mechanism referred to was the subject of Swiss patent No. 243 already discussed, which is referenced at the bottom of the advert. This patent was granted to Jean Aegler in November 1888, so it seems likely that the Aegler factory was making complete ébauches by at least 1888 or 1889.
From the trademark registered by Jean Aegler in 1885, which is unequivocally the trademark of a manufacturer of “montres” or watches, not of parts of watches or associated items, it appears that Aegler actually started to make complete movements, indeed most likely complete watches, some time between the acquisition of the new factory in 1881 and 1885.
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Aegler Xi Trademark

Aegler S.A. Trademark Xi and Ξ October 1900

Aegler Trademark Xi Ξ 1913
The letters Xi within an oval, and separately what appears at first glance to be three lines within an oval, were registered as trademarks in October 1900 by the company Vve. Jean Aegler.
The mark that appears to be simply three horizontal lines is actually the Greek uppercase letter Ξ, which is the 14th letter of the Greek alphabet. This is written in Roman letters, and pronounced, as “Xi”.
In the photograph of a trademark stamped in a case dated 1913, the mark is a combination of the two separate marks within an oval.
If it hadn't been for the domination of Aegler by their principal customers Rolex and Gruen, latterly of course Rolex who acquired Aegler in 2004, perhaps the symbol Ξ would be as well known today as is the Ω of another quite well known watch manufacturer.
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Rebberg Déposé
The word Rebberg, a German word for the vineyard or wine growing district of Bienne where the Aegler factory was located, was registered as a trademark by the company Witwe Jean Aegler on 21 January 1903. It was given the number 15427 in the Swiss register of trademarks.
The official notice of this registration reproduced here shows that in the German language the Aegler company was a Fabrikantin (manufacturer) of uhren and uhrenbestandteile, watches and watch components, and in French étuis, which means cases. Traditionally in Switzerland, watch cases were called boxes or boîtes, but around 1900 the term cases or étuis began to supersede the older term. This appears to have coincided with the introduction of wristwatches.
A term that is often seen on Aegler movements is Rebberg Déposé. In Swiss/French, déposé means to file, lodge or deposit. In this context it refers to either a registered trademark (marque déposée) or a registered design (modèle déposé).
On 25 January 1903, the company Witwe Jean Aegler registered two designs of calibres for pocket watches, Lépine and savonnette versions Nr 1 and Nr 2 respectively. This registration was given the number 9284 in the Swiss register of designs. Gottfried Furrer was the vertreter or representative who handled the registration process.
Aegler was known for making small movements, so it seems a little strange that the registration was specifically for Tashchenuhren or pocket watches. However, no size was specified by the registration so this would not have been a restriction. In fact, small movements that were originally made for ladies' fob watches were the perfect size for men's wristwatches when the demand arose.
A Swiss modèle déposé or registered design had a term of five years, after which it could be renewed or it would be automatically struck off the list. The registration of modèle déposé 9284 was renewed for the first time in 1905. In July 1906, the registration was transferred to the newly reconstituted company Les Fils de Jean Aegler Fabrique Rebberg. The registration was renewed for a second time in 1908 and for a third time in 1913. Only three renewals or extensions were allowed, so modèle déposé 9284 was struck off the list of protected designs in 1981.
When the term Rebberg Déposé is seen on an Aegler movement, it could refer to the registered trademark or the registered design, but the movement is usually one of the two registered designs shown in the image, which in consequence are usually referred to as Aegler Rebberg calibres.
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Watch Case Patent
In April 1902 Swiss patent No. 23382 was granted to Witwe Jean Aegler for a "Taschenuhrgehause", a pocket watch case.
The case design extends the bezel and back over the middle part of the case, also called the case band, so that the bezel and back meet in a single joint and the middle part of the case is umschließen und nach außen unsichtbar machen – enclosed and invisible to the outside. This would permit the substantial but unseen middle part of the case to be made of base metal while the bezel and case back were made from thin sheets of precious metal, keeping down the cost.
The significance of this patent is that it would be unusual for a company that was simply an ébauche manufacturer to patent a design of watch case, so this suggests that Aegler might have also manufactured watch cases “in house”.
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Les fils de Jean Aegler, fabrique Rebberg
In July 1906 the trademarks and patents of Veuve Jean Aegler were transferred to a new company, a "nom-collectif" or partnership "Les fils de Jean Aegler, fabrique Rebberg" (The sons of Jean Aegler, makers of Rebberg). Presumably Madam Aegler had decided to retire. The announcement shown here that was published in the Swiss trade press in 1906 refers to the transfer of registered design No. 9284 to the new partnership. The date of 25 January 1903 is the date that the design was registered.
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Rebberg Watch Co.

Aegler: manufacturers of Rebberg, Final and Rolex watches
In November 1912 the registered name of the Aegler company was changed, as shown by the announcement reproduced here published in 1912, to “Les fils de Jean Aegler, Fabrique de montres Rebberg, Final & Rolex” (The sons of Jean Aegler, manufacturers of Rebberg, Final and Rolex watches).
In Switzerland the names of at least one of the active partners had to appear in the business name of the company, so this probably signifies the retirement of Madam Aegler from the business and the takeover of the running of the company by her sons.
The notice also makes it clear that, in addition to supplying other manufacturers with movements, Aegler also sold watches under their own Rebberg brand. Aegler Rebberg branded watches are marked “Rebberg Watch Co.”
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Incorporation of Aegler S.A.

Aegler S.A. registration 1913
The notice reproduced here shows that a new, limited, company was registered on 26 September 1913, "Aegler S.A.". Notice that the composition of the company changes from a "nom collectif", a partnership, to an S.A. or "Société Anonyme", a joint-stock or limited company, a company with shareholders whose liability is limited to the amount they have invested.
The notice states that the new company Aegler S.A. was formed for the purpose of the acquisition and continuation of the previous partnerships Les fils de Jean Aegler, Jean Aegler and Witwe Jean Aegler.
In Swiss/French the word for shares in a company is "actions" so a société par actions is a joint stock company with shareholders who appoint a board of directors to run the company. Note that shares in a such a company do not have to be offered to the public, they can be held privately by the people who founded the company or sold at their discretion to raise capital. A joint stock company is a legal entity and its finances are separate from the personal finances of the shareholders, unlike a nom-collectif or partnership, where the partners are jointly and severally liable for any debts incurred by the partnership. Limited liability and joint stock companies are formed when the business is getting bigger and if unseen problems arose the consequences could be catastrophic for the individual partners, so the formation in 1913 of Aegler S.A. was a sign that the business was booming.
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Aegler and Rolex
In the Rolex Jubilee Vade Mecum, Hans Wilsdorf says that in 1905 he London placed a large order for wristwatches with Aegler. The first line of wristwatches that he placed on the market were silver watches with leather straps for men's and ladies' wear, and their success was immediate so that the range had to be widened, in particular to watches with gold cases. In view of the prevailing fashions of 1905 the success must have been with the ladies' models. This view is implicitly confirmed by Wilsdorf himself, who says that an expanding metal bracelet was launched in 1906 and our little gold watch became increasingly popular throughout the empire. A little gold watch on an expanding metal bracelet is not the sort of thing that an Edwardian gentleman would be seen dead wearing. The bracelet was called the Britannic, patented and manufactured by the London jewellers Edwin Harrop.
When Wilsdorf coined the name Rolex in 1908 he decided that he wanted to have only this name on the watches supplied to Wilsdorf & Davis by Aegler. Aegler felt that as the maker their name should be on the watches, but in the end Wilsdorf got his wish.
In 1910 an 11 ligne Rebberg watch with a lever escapement, compensation balance and Breguet overcoil balance spring was awarded a first class certificate or “bulletin d'observatoire” at the Bienne watch rating bureau. This is described in the Rolex Jubilee Vade Mecum as “the first Rolex wrist-watch chronometer”.

Aegler advert from 1910 mentioning first class bulletin d'observatoire for 11 ligne Rebberg watch with lever escapement
The Aegler advert here from March 1910 celebrates this feat but doesn't mention Wilsdorf or Rolex. This is often reported to be the first time a wristwatch had obtained a chronometer certificate but the advert doesn't mention a wristwatch, which would seem to be a curious omission and missed advertising opportunity. In fact, it says that a montre (watch) obtained the bulletin d'observatoire, not a montre bracelet (wristwatch). However, it was a notable achievement for such a small movement.
In 1913 Aegler registered Rolex as a trademark for the manufacture of watches and watch parts. From this point on the history of Wilsdorf & Davis, Aegler and Rolex becomes virtually impossible to untangle from information publicly available, and the modern Rolex foundation never divulges any of its history. However, it is clear that Aegler and Rolex remained separate companies, and that Aegler continued to supply watches to companies other than Rolex into the 1930s.
Wilsdorf & Davis owned the name Rolex, which Hans Wilsdorf was very proud of. He wanted it to appear only on the best watches supplied to him, the ones made by Aegler. Accordingly he kept pressing Aegler to increase the use of the name Rolex, and as Wilsdorf & Davis were one of Aegler's largest customers they went along with this, describing themselves in adverts as both "Manufacture d'Horlogerie Rebberg" and "Rolex Watch Co.".
The name Rolex was used by liberally by both Aegler and Wilsdorf & Davis in ways that can be very confusing. The single word "Rolex" was used as a brand name on the best watches produced by Aegler for Wilsdorf & Davis (although some of these were only 7 jewel), but it was never the name of an actual company. Conversely, the name Rolex Watch Co. on a watch does not mean that it is a Rolex watch, only that it was a product sold by the Rolex Watch Company.
Is this all a semantic exercise in splitting hairs? Maybe. But today some people advertise Rolex Watch Co. watches as if they are Rolex watches, which can trap the unwary into paying too much for a watch that more seasoned collectors do not regard as a Rolex watch, so it is good to be aware of the arguments. And caveat emptor.
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Aegler and Gruen
Another large customer of Aegler was the US firm Gruen. In recognition of this, the trading name of the Aegler company was changed to “Aegler, S.A., Fabrique des Montres Rolex & Gruen Guild A.”
Both Gruen and Rolex showed pictures of the Aegler factory in their advertising, each with their own name added to the picture of the building, implying that it was a Gruen or Rolex owned factory depending on which version of the advert that you saw.
When Rolex and Gruen were both shareholders in Aegler, the two companies sold Aegler watches only in their respective territories. Rolex had Europe, Asia and the British Empire, whilst the Gruen brothers sold Aegler watches in the US only.
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Aegler and Dimier Brothers
The images here show the movement and inside case back of a half-hunter (demi-savonnette) wristwatch retailed by Weir & Sons of Dublin & Belfast. Founded in 1869 by Thomas Weir, Weir & Sons today is a retailer on Grafton Street in Belfast.
The case has London Assay Office Import Hallmarks for sterling silver (⋅925). The date letter is the "q" of the hallmarking year from June 1911 to May 1912 - London date letter punches were changed when new wardens were elected at the end of May so were used over two calendar years.
The sponsor's mark DB in cameo in the case and the DF&C trademark on the movement are both for Dimier Brothers & Co. Dimier Brothers & Co. were a large Anglo-Swiss company importing Swiss watches into Britain from the mid-nineteenth century. The company was important in the early history of the wristwatch and exported to Switzerland leather watchstraps made in England for wristwatches. In Switzerland the company had offices in La Chaux-de-Fonds under the name Dimier Fréres & Co., hence the DF&C on the movement.
The watch movement is a Aegler Rebberg and the case has Aegler's Xi trademark.
The crown is on the left side of the case as worn, which is seen in some early wristwatches before the placement on the right hand side of the case became universal. It doesn't signify that the wearer was left handed. It is actually a much more sensible place to put the crown, because it is much less likely to get knocked, which can result in the stem breaking and the crown being lost. It is not inconvenient as many think, because a watch should never been wound or set whilst being worn.
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Kew “A” Certificate
In 1914 an 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. 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. But 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 although it was still called a Kew A certificate.
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, were subjected to separate trials at Greenwich. One of the differences was that marine box chronometers were not tested in positions, because they were suspended in gimbals to keep them dial up.
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Rolex Gets Close to Aegler
Wilsdorf opened an office in Bienne in 1916 to be near to Aegler, which was becoming increasingly important to his business. This increased further in importance when high import tariffs were imposed by the British government during the Great War (1914-1918). Previously all watches sold by Wilsdorf & Davis had been sent to London for inspection before being sent on to retailers both within Britain and the rest of the world. The high import tariffs meant that this added extra cost to watches that were destined for markets outside Britain so the Bienne office took over the duty of inspecting these watches and dispatching them direct to their destination.
This was the start of a move headquarters of Wilsdorf & Davis and Rolex from London to Switzerland. If it hadn't been for the Great War and British import duties, Rolex might still be a British company.

Aegler SA 1929, Manufacture of Rolex & Gruen Watches.
In 1919 a new company was incorporated in Geneva by Wilsdorf & Davis as Montres Rolex SA. Its manufactory was listed as "Manufacture des Montres Rolex, Aegler S.A." but the two companies, Aegler S.A. Bienne and Montres Rolex S.A. Geneva, were legally separate entities. Aegler also had other customers, the largest of which was the US firm Gruen. The notice here from 1929 shows that Aegler Ltd. was the manufacturer of Rolex and Gruen Guild watches.
Over the next few years this remained the situation. Aegler supplied Rolex branded watches to Montres Rolex S.A. who organised their distribution to approved outlets, and advertising and marketing. Aegler also supplied watches to Gruen, who sold them in the USA, and to others. Montres Rolex S.A. and Gruen were Aegler's biggest customers and they had a mutually beneficial arrangement where Gruen would only sell watches in the USA and Montres Rolex sold watches to the rest of the world. As the USA was the wealthiest consumer market in the world at the time this was not so unbalanced as it sounds.
The image here shows a drawing of the Aegler factory in 1920. If you compare it to the drawing of the first factory, you can see that is now the smallest block at the right hand end and carries the date 1881. All three parts of the factory are dated, the oldest factory carries the date 1881. The block in the centre is dated 1896 - 1912, the block on the left of that is dated 1914.
The three blocks of the factory are at numbers 80-82 Höheweg. The original 1881 building was modified by adding watch workshops in the roof space in 1896 by Magri frères for the widow J. Aegler. Extensions to the factory 1897, 1898, 1907, 1911, 1912 and 1914 by Magri frères, Jules Aebi, Römer & Fehlbaum and Corti frères for the widow and her two sons Hermann and Hans Aegler. In 1914 the factory had around 200 employees. The complex of hipped roof buildings with regular windows is characterized by the redesigns carried out by Römer & Fehlbaum in 1912 and 1914.
On the roof of the main blocks in the image are two banners. The first says "Aegler S.A.", the second "Montre Rolex". These banners probably never existed in reality but were drawn in on the advertisement image. When the same image was reproduced in adverts in America, the "Montre Rolex" was altered to "Montre Gruen".
Montres Rolex and Gruen did not take all the watches that Aegler could make, so Aegler also continued to supply watches to other companies. At the same time, Wilsdorf was interested in making watches that could be sold at lower price points than the top line Rolex branded watches, so he bought in movements and watches from other manufacturers such as Fontainemelon that were used in watches carrying names such as Marconi, Unicorn and Tudor.
During the Great War Emile Borer, nephew and ultimately successor to Hermann Aegler, joined the Aegler factory personnel as an engineer. Unlike Wilsdorf, who freely admitted he was no watchmaker, Borer was a watchmaker to his finger tips. He soon became responsible for developing new technology and developed an automatic winding system that was patented by Aegler in 1931. A book about watch servicing and repairing by Borer was published in English as Modern Watch Repairing. The first edition was published in 1931, the revised second edition shown here in 1937. It's a very good book for its time. Emile Borer was appointed as a director of Aegler in 1931 and subsequently became Chief Technical Director, and then in 1944 General Manager of Aegler S.A.
Business between Rolex and Aegler flourished until by 1920 Rolex was Aegler’s largest customer. The post war slump that culminated in the Wall Street Crash of 1929 and the ensuing Great Depression hit Montres Rolex's business hard, and Hermann Aegler invested in the survival of his largest customer by acquiring 6,960 shares of Montres Rolex S.A. and was appointed to the board. It is said that he was given these shares, but there must have been some sort of quid-pro-quo. As business recovered both Rolex and Gruen became large shareholders in Aegler.
The Aegler company adopted the trading name "Aegler, S.A., Fabrique des Montres Rolex & Gruen Guild A". Gruen and Montres Rolex adverts of the period show pictures of the Aegler factory with either Rolex or Gruen on the factory roof, implying that it was a Gruen or Rolex owned factory. As the Gruen adverts were for US display and Montres Rolex adverts for display outside the US this dichotomy was not obvious to consumers. Over the years various names were used to identify the Aegler factory more and more closely with Rolex, but these were just trading names. The legal entity that owned the factory was Aegler S.A., which was owned by the Aegler and Borer families.
In the 1930s Gruen and Montres Rolex S.A. sold their shares in Aegler S.A. back to the company, and Aegler S.A. sold its shares in Montres Rolex S.A. to Wilsdorf. In 1936 Gruen ceased purchasing watches from Aegler and Montres Rolex S.A. Geneva agreed to take up the entire production of the Aegler S.A. factory in Bienne. In September 1936 the company changed its corporate name, dropping the reference to Gruen and styling itself “Manufacture des Montres Rolex, Aegler Societe Anonyme”, although it was now wholly owned again by the Aegler family.
In 1969 Harry Borer, son of Emile Borer, took over management of Aegler S.A. and oversaw the expansion of the company, with eventually seven new production buildings being built in the Champs-de-Boujean industrial area of Bienne.
Rolex Buys Aegler

Bloomberg © 2016: Acquisition of Aegler by Rolex in 2004
The arrangement of Aegler SA making watches for Rolex to sell continued until 31 December 2004. The Borer family decided that they wanted to sell the Aegler company, and it was bought by Rolex.
The two companies remained separate legal entities until 2004 when Harry Borer sold Aegler S.A. to Montres Rolex S.A. and the Rolex Watch Company finally owned the factory which made Rolex watches. The company overview by Bloomberg reproduced here tells the story in a few words. As the Bloomberg report shows, the manufacturing facility in Bienne is still a separate company called Manufacture des Montres Rolex SA, a wholly owned subsidiary of Rolex SA.
The company that is now called “Manufacture des Montres Rolex S.A.” is stated to have been incorporated in 1913. This is the company that was incorporated in 1913 as Aegler SA, irrespective of what trading names or styles the company adopted at various times, until it was taken over by Rolex and formally renamed.
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Aegler Rebberg Movements
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.
Aegler manufactured movements in its ébauche factory in the Rebberg district of Bienne, and as a consequence of this Rebberg was a registered as a trade mark by Aegler, hence these movements are often referred to as Rebberg movements, even if they are not stamped with the Rebberg name. If they are stamped Rebberg it is often on the bottom plate and under the dial so not normally visible.
The image of the Rebberg Watch Co. movement is courtesy of eBay member allthatsparkles69. The image of the Rolex 13 ligne savonnette movement is of my grandfather's wristwatch movement. All the other movements here are by kind permission of Owen Gilchrist.
The movements are all photographed with point where the stem enters the movement at the top, at 12 o'clock. This is the way that movements are shown in reference books, so it makes it a lot easier to look up a particular calibre if the photograph is presented in the same orientation. All the movements are Lépine layout with the exception of the one savonnette. The very distinctive shape of the centre bridge identifies them all as Aegler Rebberg movements.
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Unusual Rebberg Movement
The larger image shows an unusual Aegler Rebberg savonnette movement marked Rolex on the ratchet wheel. This movement was used in small numbers of Rolex watches, including Oysters, in the late 1920s. The most obvious difference from the earlier Rebberg movements 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. This movement was only used for a few years until it was replaced by a slightly different Aegler design known as the “10½ ligne Hunter”.
This movement was also supplied to Gruen in the USA. It is listed as a Gruen 825 with small seconds, 826 Lépine and 827 savonnette. The 826 and 827 came in centre seconds versions. The black and white image here shows a Gruen 826 Lépine movement with indirect centre seconds. The cover plate for the keyless mechanism includes the detent spring which holds the stem in the winding or setting position. Earlier keyless mechanisms, such as those in the earlier Rebberg movements, had the detent made from separate levers and springs, so making the detent part of the cover plate made it cheaper and easier to manufacture and assemble.
The keyless mechanism 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.
Dr Ranfft identifies this movement as an Alpina 819, Gruen 819 and Rolex 600.
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Copyright © David Boettcher 2005 - 2023 all rights reserved. This page updated May 2023. W3CMVS. Back to the top of the page.