An exceptional Helvetia Semi Hunter Trench watch from 1918, with a large 35mm silver case and beautiful original crown. The enamel dial is perfect, with perfect original Radium lume, even on the hands. The case is extremely well designed and constructed, with a coin edge screw back to the rear. The front cover is in good condition with very minimal wear to the black enamel track and numerals. It has a good quality Swiss made 15 jewel movement, which is yet to be identified but appears to be an Aegler movement.
 
The case is signed ‘Brevet 71363’ which is an early hermetic sealed design with a flip front cover, that was patented in June 1915 by Charles Zurbrugg of Bienne. This was published in the Swiss Confederation Office of the Federal Property Intellectuelle Explanatory Dtnventionj No. 71363, June 23, 1915, 7 11 – 71f P-Class. Hans Wilsdorf, the owner of Rolex, owned patent no.71362 that was issued months earlier than Zurbrugg’s patent. Later Rolex cases of the same design used the Zurbrugg patent no.71363 on their cases, so it is likely that Wilsdorf purchased the patent from Zurbrugg, or decided to use those cases to help fulfil orders in the UK market.
 
The case is marked Depose No. 9846 which relates to a 1903 patent by the Anglo-Swiss company Dimier Brothers, who registered a design of a wristwatch with fixed wire lugs and a leather strap. This is the earliest documented evidence of watches with wire lugs and one-piece leather strap, pre-dating classic Great War trench watches. This design and depose held clout with this message published in 1907;
La Fédération Horlogère Suisse, October 1907 To avoid trouble and misunderstandings, we inform Gentlemen makers of watch cases of gold, silver and metal, and Gentlemen watch manufacturers of Switzerland, the curved handles for wristwatches are our registered design No. 9846 dated July 29, 1903. We will pursue anyone who manufacture watches with these handles, without having previously made arrangements for a royalty to be paid to us, and that does not send his watch cases to our factory in La Chaux-de-Fonds to have our registered mark stamped in the case back.
 
The watch itself:
The dial is of classic early trench watch style, the railroad style minute track runs around the exterior of the watch, with an inset sub-second track at 6 O’clock. The numerals are black base tone with aged, original radium lume in-fill. The 12 O’clock is red, designed for legibility. The hands are original, and they are in good, aged condition. They are of cathedral style with original lume in-fill. This is perfect and there is no loss of the lume.
 
The internal crystal is a well-matched replacement, which fits the low profile of the watch. It is in very good condition. The crown is original and is made of Silver. It has a beautiful finish with no marks.
The lid of the case is in good condition, being smooth with only light surface scratching. The enamel on the front has some very slight areas of wear but is still in good original condition. The button at 6 O’clock depresses as it should and flips up the lid. The spring holding the top seems to be compressed, meaning that it doesn’t reach a 45-degree angle, but rather 30 degrees. This is the only issue with the watch but is minor and very solvable. 
The movement is original and has a jewel count of 15, with a frequency of 18,000 BPH. It strikes me as an Aegler movement, but this is to be confirmed.
The service history of the watch is not known, and the watch has not been serviced by us. Cosmetically the movement is very good, with no. visible discolouration or dirt. Functionally the movement is very good and would appear to have been serviced within the last 5 years.
It has a daily gain of +39 seconds a day, with an amplitude of 280 degrees and a beat error of 1.4 m/s. For a 100-year-old piece, this is very acceptable.
 
Please see the images as these compliment and aid the description provided below.
 
Dial:
The dial is original and is in very good condition. It is made of enamel, which is free of any cracking, hairline fractures or chips. This is uncommon after this long and makes this a very good example. Of classic early trench watch style, the rail road style minute track runs around the exterior of the watch, with an inset sub-second track at 6 O’clock. The numerals are black base tone with aged, original radium lume in-fill. The 12 O’clock is red, designed for legibility.
Hands:
The hands are original, and they are in good, aged condition. They are of cathedral style with original lume in-fill. This is perfect and there is no loss of the lume. The hands would have been thermally blued, but they have aged to a slightly bronzed tone. All hands are original and meet the margins of the dial as they should.
Glass:
The internal crystal is a well-matched replacement, which fits the low profile of the watch. It is in very good condition.
Crown:
The crown is original and is made of Silver. It has a beautiful finish with no marks. It functions as it should, winding the watch and setting the hands.
Flip top front cover:
The lid of the case is in good condition, being smooth with only light surface scratching. The enamel on the front has some very slight areas of wear but is still in good original condition. The Semi-hunter crystal is clear and in good condition. The button at 6 O’clock depresses as it should and flips up the lid. The spring holding the top seems to be compressed, meaning that it doesn’t reach a 45-degree angle, but rather 30 degrees. This is the only issue with the watch but is minor and very solvable.
Case:
The main body of the case is made from silver and is in good condition with light surface scratching. The sides have a polished finish.
Caseback:
The case back is made of silver and is in good condition with the exterior of the case back having little marking. The coin edge finish has been slightly polished by wear against the wrist, but it’s still well defined. It has only light surface scratching but no noticeable gouges or nicks. I
nside, it is signed: Brevet 71363, Depose No. 9846. It has UK hallmarking for imported silver. It has the date letter C, which dates it to 1918. The sponsor mark is Arthur George Randall who was a well-known importer into the UK in the first quarter of the 20th century. It is finished inside with peerlage and there are some deeper scratches but these don’t detract from any of the signing which is clear.
Strap:
The strap is a new light brown, good quality leather strap, which is for fixed lugs, with metal folding tabs. It will fit up to an 8.5” wrist. The buckle is not original but is stainless steel and matches the watch well.
Movement:
The movement is original and has a jewel count of 15, with a frequency of 18,000 BPH. It's manufactured by Helvetia and is one of their early in-house movements.  It has a daily gain of +39 seconds a day, with an amplitude of 280 degrees and a beat error of 1.4 m/s. 
Case dimensions:
Case width: 35mm
Case width with crown: 37.7mm
Case length: 35mm 
Case length lug to lug: 42mm
Case Depth: 11.8mm
Lug width: 12mm