Below is a scan of an Omega advertisement from French watchmaker and jeweller (Horlogerie-Bijouterie) J. Magnaux in Périgueux dating back to 1905. It shows the local time in different cities around the world, compared with midday in Paris.

GMT (Greenwich Mean Time) was so named because of Britain’s history as a maritime nation, as was the Greenwich Meridian (Prime Meridian zero degrees longitude). GMT later became UTC. GMT was not adopted by France until 1911 and in 1905 the solar time in Paris was used across metropolitan France. Similarly, local time in countries around the world was based on solar time.
This advertisement shows that at midday in Paris, the time in London (GMT) was 1151 and in Berlin it was 1308. Hanoi was 1854 (nowadays it would be 1900), Tokyo was 2110 (nowadays it would be 2100). San Francisco looks a bit wild to me!

I cannot explain the notations for each day of the year on the reverse side (maybe Tire‑comedon can help?).
Tom

 

There are the names of the saints that are celebrated this day (name preceded by S or S°), christian célébrations (epiphanie etc...), the seasons printemps =spring, été = summer, automne = automn, hiver = winter), the increase/decrease of daylight for each day. (les jours cr. de ..h means les jours croissent de .. heures: days are increasing by ..hours. Les jours decr means les jours décroissent : days are decreasing.).

 

That wonderful Omega production ‘A Journey Through Time’ contains SO MUCH information: does any other manufacturer offer anything similar? I keep stumbling on things I have either not noticed before or which I have forgotten. For ‘modern’ items (post-1950?), maybe there are other publications that are of value – but for my period (1894 to about 1950), there is nothing to touch AJTT.

Sure enough, hot on the heels of my post from three days ago with the 1905 advertisement (from French retailer J. Magnaux in Périgueux), I have just noticed Page 62 in AJTT which shows a very similar advertisement by Kirby Beard (Paris) from 1903 – with a better explanation than mine.
Some of the cities vary considerably from the 1905 times (and I think are also questionable) – but that’s another story.

In the meantime, many thanks to Tire-comedon for the explanation of the calendar entries.
Tom

 

And a short note on UTC, which is Coordinated Universal Time. Coordinated with what, do you ask, and why are the letters in the wrong order?

It's the time coordinated between two master time clocks, Universal Time 1 (UT1) and Universal Time 2 (UT2), at the National Institute for Standards and Technology.

Tom

 

Interesting ad. I wonder what the meaning is of the lady getting prepped and the two gentlemen in the background, who has the Omega, her or the gentlemen.

Even though I live on the prime meridian, we are on CET +1 hour from GMT, which is really fine with me, it stays lighter in the evening. Don't care much about the morning being dark, the only morning chore is to feed my donkeys and if it's dark, then tend to stay in bed and keep quiet...

Rob

 

I think the lady has the latest Speedmaster (equivalent) in her trinket box (her Dad is the agent for Omega). The two gentlemen are collectors, hoping to persuade her to part with it.

Re time differences, this is political! Solar time changes one hour for 15 degrees of longitude. USA east coast to west coast is (about) 48 degrees longitude – and sure enough 3 hours time difference. However (most of) Europe is (for political reasons) on one time zone – although the longitude between (for example) Madrid and Warsaw is nearly 25 degrees. As for whether it gets dark earlier or later, it’s more important how far north (short winter days) or south (midnight sun) you live.

Tom

 

I read the San Francisco clock in the advertisement as being 0819 – with Paris at 1200. That’s a time difference of 3 hours 41 minutes. Depending on the time system you are using, I would expect San Francisco to be about 0400 when Paris (was) at 1200. That’s what I mean by San Francisco time looking ‘a bit wild’. Sorry but at no stage has the history of time in the United States shown a time difference with Paris of (less than) 4 hours!

But I don’t think it’s important – the nice thing is the atmosphere of the old Omega advert.
Tom