Jump to content
  • Sign Up to reply and join the friendliest Watch Forum on the web. Stick around, get to 50 posts and gain access to your full profile and additional features such as a personal messaging system, chat room and the sales forum PLUS the chance to enter our regular giveaways.

Questions about Zenith MK IV, MK V watches of the RFC / RNAS and HS 3 watch of the Royal Navy

Recommended Posts

Good afternoon,
As a collector of old Zenith watches, I am not only interested in the technology, but also in the history of these watches. As you know, Zenith started supplying their watches to countries all over the world at the end of the 19th century. Larger orders from institutions first came from the railway companies of some countries, later government orders were added, especially for the military. From around 1914, Zenith also supplied the British government with Mark IV A pocket watches for the RFC and later for the RNAS. From 1916, Mark V watches were also added.
I have been researching these MK IV and MK V watches for a few weeks now, but also the H.S. 3 watches by Zenith from WW II.
The technology of the watches is known to me so far, also most of the calibres up to the manufacturer codes on the dials of the MK V watches. The patent situation for the Octava movement is also known as far as it goes.

Where I get stuck is the military standards of the time for these watches. Which British institution was responsible for the standardisation and are these still accessible somewhere? Where could I find sources or information on the further details of these watches? Are there any British online archives of historical records from the period relating to military watches? Or has something similar already been discussed here in the forum? A link to such topics would already help me.

To avoid misunderstandings, I am talking about watches of this type:


If anyone has questions about their own Zenith pocket watches, I would be happy to try to answer them.

Many greetings,




  • Like 1
Link to comment
Share on other sites

What an interesting initial post, @Herold, and welcome to the Forum. I am sure your knowledge of Zenith will prove to be helpful in Future Forum posts.

I am not quite sure what you mean by "military standards of time" as opposed to the standardization of time generally in the UK based on GMT. Until the middle of the 19th century, almost every town kept its own time based on the position of the sun. However, with the expansion of the railways in the UK, and the use of railway timetables, it became necessary for some form of standardization of time to be laid down across the country, remembering that there were as yet no national or international conventions setting out rules as to how to measure time. Railway companies had already started to introduce a single standard of time across their networks in the 1840s, mainly using Greenwich Mean Time (GMT), and in December 1847, GMT was adopted by the Railway Clearing House as "Railway Time" across the UK. By the mid-1850s, most public clocks displayed GMT, although it didn't become  Britain's legal standard time until 1880.

The international situation was still problematic after 1880 when, in 1884, GMT was recommended as the Prime Meridian of the world. The USA had already adopted GMT as the basis of its own national time zone system, and furthermore, by the late 19th century, 72% of the world's commerce relied on charts which used Greenwich as the Prime Meridian. Thus, because it seemed that naming Greenwich as Longitude 0° would benefit the greatest number of people, GMT was adopted as standard time internationally and the Prime Meridian at Greenwich became the centre of world time and the basis for the world's time zones.

Your use of the term "military" in your enquiry makes me wonder if you are referring to the use of so-called "Military Time", which is essentially the use of the twenty-four-hour clock rather than the twelve-hour system. If you are seeking information about the history of the twenty-four-hour system than a  useful introduction is at militarytimeconverter.org/military-time-history/#:~:text=Military%20Time%20was%20invented%20by,in%20the%20early%202020th%20century  The use of Military Time goes way back in history, but for our purposes, it seems that the First World War was where its military use became important for a number of reasons; Military Time does not actually represent a time standardization, however, but merely the conversion of the twelve-hour-clock into the twenty-four-hour system. 


Link to comment
Share on other sites

Oh, sorry, I didn't mean the time standard, of course. But thanks anyway for your answer and your explanations.

I meant the standards that the watches had to meet in order to be accepted into military service. Surely there were requirements and tests that had to be passed according to set criteria?

For the rules for the HS 3 watches in WW2, it was probably the Hydrographic Department. But who set the rules in WW1 for the MK IV and MK V watches, I haven't found out yet.
And I would be interested to know which tests the clocks had to pass.

For example, the French "Norme AIR 7620" from the 1930s was responsible for the French on-board clocks in the aircraft.
The test conditions were as follows:

Tests for accuracy

1. three days at room temperature +10 to +20 °C (watches were wound daily)
The rate deviation was not allowed to exceed 15 seconds on three consecutive days.

2. 24-hour temperature test at -4°C

3. 24 hours temperature test at -30°C

4. 24 hours temperature test at +40°C

For each test, the rate deviation must not exceed 45 seconds.

5. like test 1.
The rate deviation was not allowed to exceed 15 seconds on three consecutive days.

Between the individual tests, the watches were stored for 24 hours at room temperature in order to simulate the temperature fluctuations in high layers of air and on the ground to which the watches were exposed in use.

Special test Acceleration test

1. the watches were subjected to horizontal vibrations of 1/10 mm amplitude and repetition frequencies between 1000 and 3000 Hertz for 24 hours in a vertical position.

2. the watches were subjected to vertical vibrations with an amplitude of 10 mm and a repetition frequency of approx. 600 Hertz for 30 seconds.

No failure of the movement was allowed to occur during either test.

(It goes without saying that the first test simulated an engine in flight and the second test simulated runways).

Special test magnetism

The watches were exposed to a magnetic field for 24 hours. No failure was allowed to occur.

Unfortunately, there is no information about the strength of the magnetic field.

Special leak test

The watches were exposed to 250 ml and 1000 ml of artificial rain for 5 minutes and were not allowed to show any traces of water inside the case at the end of the test.

Visibility and readability test

There is said to have been a test in this regard, but the criteria are not known.


This is the data I am looking for on the British watches.
I hope it's all easy to understand because I'm working with an automatic translator. It's quicker for me than trying my old school English, which is not good enough for technical descriptions anyway.

Many greetings,




Link to comment
Share on other sites

Hi spinynorman, thanks for the tip about the military section. I thought it was only about replicas of military watches, because it says "military style watches" in the description.

I will put a link to my contribution here.

But first i have to find a proper hosting service. so far i have never worked with such services.

all beginnings are difficult

many greetings,


Link to comment
Share on other sites

Thanks for acknowledging my contribution to this thread, @Herold. I think my confusion was justifiable, and I hope you find the information you are seeking. I would presume that most major military organizations past and present that sponsor or provide watches for servicemen would apply criteria or standards for those watches, and this subject could turn out to be pretty big when considering it on an international scale.:) 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...