Blog: Rotherham & Sons Hermetic Wristwatch

Date: 23 May 2023

I make additions and corrections to this web site frequently, but because they are buried somewhere on one of the pages the changes are not very noticeable. I decided to create this blog to highlight new material. Here below you will find part of one of the pages that is either completely new or I have recently changed or added to significantly.

This entry is from the page about the Coventry watchmaking company Rotherham & Sons.

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

Rotherham & Sons Hermetic Wristwatch

Jean Finger patent CH 89276: Click image to enlarge

Rotherham & Sons Hermetic Wristwatch Bezel Off: Click image to enlarge

Rotherham & Sons Hermetic Wristwatch Face: Click image to enlarge

At a glance, the wristwatch in the image here appears quite normal. It was made in the 1920s and has the fixed wire lugs for the wrist strap that were being gradually superseded by horns and bars, and the skeleton hands and numerals to take radioluminescent paint that were a hang-over from the trench watches of the Great War.

But a second glance reveals that there is no external crown for winding the mainspring and setting the time.

The second image reveals the secret. The bezel unscrews, revealing a smaller watch within which does have a crown. To the left of the 9 is a joint and outside the 5 is tab that can be caught with a fingernail to swing out the small watch on the joint to allow access to the crown so that the watch can be wound and set.

This elementary, almost brutally simple, way of protecting a watch from moisture was invented in America by Frederick Gruen in 1918, who was granted a patent for it on 20 May 1919, number U.S. 1,303,888 "Wrist-Watch". A few years later, the same design was invented in Switzerland by Jean Finger, a watch case maker of Longeau, Berne, Switzerland, who was granted a patent for it on 4 January 1921, number CH 89276 "Montre a remontoire avec boitier protecteur" (stem winding watch with protective box).

Rotherham & Sons Hermetic Wristwatch Case Back: Click image to enlarge

Rotherham & Sons Hermetic Wristwatch Open: Click image to enlarge

The granting of two separate but identical patents like this to Gruen and Finger should have been prevented by international patent law but evidently wasn't. There is no indication that either party tried to register their patent in the other's country or challenged the other's patent so it seems that they simply existed in parallel. <

The case back carries the trademark of the initials FB over a key registered by François Borgel in 1887. By the time this watch was made, François Borgel was long dead and his daughter Louisa had sold the company to the Taubert family, who continued to use the famous trademark. The relationship between the Borgel Company and Jean Finger is not known but since Finger held the patent for this type of case, the cases must have been made by the Borgel Company under licence.

The case back carries Glasgow Assay Office hallmarks for sterling (0.925) silver. The date letter is the “g” of the Glasgow Assay Office hallmarking year that ran from July 1929 to June 1930.

The sponsor's mark “R&S” in cameo within a rectangular surround was entered at the Glasgow Assay Office by Rotherham & Sons. The date of registration of this mark is not recorded, but an identical mark was entered at the Edinburgh Assay Office on 1 August 1926, so the date of the Glasgow entry is most likely also 1926.

Rotherham & Sons Hermetic Wristwatch Movement: Click image to enlarge

In 1926 the Electa watch movement factory and its contents were purchased by Rotherham and Sons from Gallet after the Electa business was liquidated. The coincidence of this date and the registration of punches at the Edinburgh and Glasgow Assay Offices is notable.

The movement is a small jewelled Swiss lever with 15 jewels that carries the Rotherham & Sons R&S trademark. It has not yet been identified, but from the coincidence of dates discussed above it seems likely that it is an Electa movement made in the factory then owned by Rotherhams.

The small domed disc next to the movement is a cuvette that snaps onto the back of the movement carrier ring that is jointed to the watch case. This gives some extra protection to the movement, especially when it is flipped out of the case for winding and setting.