NOSTALGY FOR .........IWC POCKET WATCHES.

Thank you and Cellar for the explanatiom!
Regards Hans

Of course, as "always" Cellar is right explaining the definition of a "half-chronometer". It is a watch having an escapement compounded of the lever and chronometer escapements. Also the literature tells us that a "half-chronometer" is a fine lever-escapement watch, adjusted for temperatue.
The practical consequence is the following. Half-chronometers are not belonging to the category of watches that have been tested at the Astronomical Observatories in Europe. They have no "Bulletin de Marche" nor a "Chronometer Certificate". They have been engraved with the qualification "Half-Chronometer" awarded by its producers and as the term "Chronometer" or "Half-Chronometer" is not protected by any patent or law, every manufacturer is free to declare its watches to be a chronometer or half of it...
This weekend we will post Part II of the series on IWC chronometer watches.
Keep tuned....
Adrian (alwaysiwc) on behave of the team.

Adrian, believe me - we are already "tuned in" and anxiously awaiting part two!

what are we going to do when the series closes (oh so soon!) ?

Best regards
Mark

Hi Adrian et al,
Correct me if I am wrong. The terms - chronometer and half chronometer - mean that, at one given time, the movements in the pws with that designation in the case or the dial, were tested and fine tuned to a high degree of accuracy, under test conditions. It did not mean that those movements were manufactured with higher quality parts or assembled with extra care, to earn that designation. It did not guarantee the movement would maintain that performance once faced with daily use outside the factory, or the testing agency.
Is there a record of which calibers had (selected) movements that earned the label chronometer or half chronometer?

Hi Antonio,
Perhaps hidden in the text we said : chronometer just means "measuring time"
Unfortunately an international standard how accurately this time should be measured did never exist. So there were simple test that could last a few days, defined and carried out by the manufacture itself. These simple tests existed of measuring inaccuracy of an individual watch in different positions and at a few different positions. It was known that the accuracy was dependant from the sensitive balance and balance spring for temperature changes and from gravity. Magnetism, also a force that influences accuracy, was not taken into account for testing a watch. IWC was probably one of the Swiss watch makers that developed these "homemade" tests around 1900. The watch got than a chronometer certificate or in German language : "Gangschein". The parts of the movements were not specially made, but those machine produced parts were selected with the lowest possible tolerances. At the end a skilled Regulator or "Régleur" fine-tuned the balance spring by hand in such way that the watch became extremely accurate. The page published by Cellar here in this thread shows that the customer had to pay for it : 20 Swiss Francs. These watches got often an engravement on the movement : "Quality Extra". Besides the more simple in-house tests, such watch could be sent to an Astronomical Observatory, where in fact the same tests were carried out but much longer (up to 45 days), many more positions and at more temperatures. But even these independant Observatories had no agreed international standard about the exact rules to apply. It is known that Vacheron Constantin sent watches to the Observatory in Geneva. Once they had passed the chronometer test there successfully, they were once again sent to the Observatory of Kew, the most severe testing institute.Here several "Geneva" approved watches were turned down : no Kew certificate! I do not know for sure whether in the Archives information exists about which watches got an Observatory test and certificate. Documented in the archives for sure is whether certain movements were regulated to high standards : "réglage speciale". Although from time to time a century old IWC PW's are offered on the market, complete with original box, it is extremely rare that one sees an official "Bulletin de March" or Kew Certificate. Your question which calibers were sent to the Obsevatories is answered by Meis in his book :
Cal. 52/53, 65/66 and of course 71/72. I guess from an estimation in the literature that 200-250 IWC watches have been tested in Neuchâtel and in Kew. Most of them were cal. 71/72 and many were submitted to Kew by Stauffer in London.
This weekend more on this topic (Part II)
Kind regards,
Adrian,
(alwaysiwc).

Thanks Adrian,
It is significant, at least to me, that the PWs destined to be labeled Chronometre were manufactured with selected parts with the lowest tolerance, and then submitted to a fine-tune to achieve the highest possible accuracy, and not randomly picked up from the production line, and then fine-tuned. In the latter case the Chronometre label would have been little more than a gimmick.

It is interesting that cal. 67 is not among the list of calibers that were "elevated" to Chronometre status, since they equipped KM's deck watches.

Looking forward to part II and, as others already pointed out before, this series will me missed, but I hope you and the team will keep on contributing with you knowledge to the forum.

Antonio,
The point you bring up about cal 67 is really interesting. The German Army during WW II had its own "chronometer testing program" in Leipzig and Gesundbrunnen, Germany. IWC cal 67 was primarily selected by he German Navy because it was extremely sturdy and solid. Therefore alone PW's with this caliber could serve for military purposes. The Germans selected their navigation watches among the best Swiss manufacturers : Patek Philippe, Vacheron Constatin, Ulysse Nardin and also IWC. According to its accuracy, tested in Germany, Navigation watches were awarded to be class I or class II. IWC, cal 67 was considered to be a class II watch, although its accuracy was in many cases achieving the class I standards. On the caseback of the Kriegsmarine (KM) cal. 67, one can find "Kl II" ( class II), if not polished away together with the German Eagle and swastica, being the original engravement. At a certain point in time, the German Army had a shortage of cal. 67 watches and IWC could not deliver more watches at short notice. Than the German authorities decided to confiscate CIVILIAN cal. 67 watches. These watches were tested as well for accuracy in Gesundbrunnen and declared military watches , class 111. As such they were suitable to serve in the Navy. It is unknown to me, which tests were applied by the military. For sure the standards were again different from the standards used at IWC and the standards used at the European Astronomical Observatories. However, if a standard produced IWC cal. 67 was approved by the German Navy, one can assume that this caliber is a reliable mechanical timepiece, not typically marked as a "chronometer" but so accurate that it was used successfully on German war ships and submarines. Moreover, after the ending of WW II in 1945, the successor of the Kriegsmarine : the German Navy Bund, used cal 67 as a reliable, precise mechanical watch on board of their already completely computerised ships, until 1966 !
The background was this. Suppose the power supply on the ship breaks down : all the electric clocks stop .... but the cal 67 reference IWC PW ticks on....
Kind regards,
Adrian
(alwaysiwc).

The fact that the German Navy still used mechanical watches until 1986 is not surprising. Preparing for, and defending against worst case scenarions is why countries spend such a large portion of their GDP on their Armed Forces.
A little factoid re worst case scenarios. The B747 used by POTUS, better know as Air Force One (when POTUS is aboard), in spite of all the electronics, has the capability for celestial navigation. I doubt, however, that the navigator would be using a IWC Mark 11. :-)

IWC Chronometers Part II
About 80 years after launching the 1907 Zürich Schützenuhr with in-house "Gangschein, IWC produced the limited series of Scrabaeus PW's. This watch has been discussed here several times. Each timepiece came with an in-house "chronometer certificate" but now deviations were measured, using different parameters....

....The ultimate testing was performed by an independant Astronomical Observatory. In Neuchâtel, this cal. 66 IWC fingerbridge watch was awarded a "Bulletin de Marche"...

.....The same reward came with this beautifull cal 71/72 "fishtail" watch, dating from 1904...

....Here one can see the so-called "kew-A" certificate. There were also B-certificates, where the watches were tsted for a shorter period and less stringent. The chronometer test at Kew were transmissed to the National Physics Laboratory (NPL) but the name "Kew" test persisted...

...Here a scheme about the different positions in which a PW was tested to gain the Kew A certificate.
Other than the well known Swiss brands of the era, IWC did not enter the chronometer competitions, contest where the best brands competed to deliver the utmost accurate watch...

....The strategy of IWC was more to build machine made watches of good, reliable and constant quality, but it is clear that these watches were "Observatory-proof". To pass the test successfully a certain number of points "marks" were necessary out of the maximum of 100 marks. The maximum realised by a cal. 71 IWC was 88 marks. Besides the number of marks, a watch could be awarded the classification "especially good". This honour was than depicted on the certificate....

....In summary, If you have an IWC chronometer, it could be an accurate watch produced and tested by the company or it might be an extraordinary highly accurate timepiece, tested by an Astronomical Observatory and therefore of the best quality available. As said previously, an international standard for chronometers never existed. The currently used "COSC" (Contrôle Officiel Suisse des Chronomètres) was adopted in 1973. It is far less strict than the Observatory tests. The Observatory testing programs were not anymore needed after WW II, after the arrival of the atomic clock and when electric and quartz time keeping took over from mechanical watches. The Astronomical Observatories in Europe closed one after another. The Observatories of today are located in unpolluted distant places such as Chili and the Canarian Islands and usually they are not open to the public. But I had the opportunity to visit the Observatory of La Palma, Canarian Islands in 2010. More than 10 different telescopes have been built on the rim of an imploded volcano called the Caldeira de Taburiente. This volcano gave birth to the Island of La Palma, 2 million years ago. It was here that one of scientists explained to me about "neutron" stars. He and I forgot completely about time until he asked me : "Tell me, is it time for lunch?"
Than I looked at my 1973 Automatic IWC, Blue Sunray Dialled, IWC Yacht Club and said : "Yes sir, I guess it is.....
Kind regards,
H-G Aberle,
R.Birkenkämper,
T.Koenig,
A v d Meijden,
(alwaysiwc).

Incredible information, Adrian, et al. Thanks again for sharing your knowledge and passion.

Excellent additional info about the processes of certification.
We have the Who, What, When, Where, and even the How, but we do not have the Why.
So my question is, Why? - for what purpose - were those watches so carefully assembled, the movement carefully finished, and then painstakingly fine-tuned?
All IWCs I have seen with the label Chronometre, (I know that Chrono is Greek for time -chronos- and -Metre- for -metron-) have gold cases, which appears to preclude those PW being "tool" watches used for navigation, or any other activity requiring an accurate time measuring.
I wonder if they were destined to the part of the population on a rigorous schedule and obsessed with being always on time for everything. :-)

Educational, enjoyable- a fine read.

I keep learning....

Nelson