Just a short presentation (you scroll, you choose): Brief recap: Sundials indicate true solar time. There are three adjustements to convert it to the time on our watches (standard time): Mean time Standard time (the same hour for an entire territory) and Daylight saving Time The Papophoplon gives you those
In La Ciotat, on the port, there is a nice sundial: It is an equatorial sundial, dating from 1873 called the barometer sundial, because it includes a barometer. Like most sundials, it shows solar time, which is not the same as the time on our watches (standard time).To enable it
The customisable Papophoplon You can now make your own Papophoplon. Enter your longitude and time zone offset from Coordinated Universal Time (UTC) to find out the solar time for every day of the year! You can use it in two different ways: 1. Play online Tick the ‘Vector’ box to
Since 1901, the Lépine Competition has been showcasing passionate inventors, both amateur and professional, who devise ingenious solutions to improve our daily lives. It does not necessarily reward “technological revolutions”, but rather: simple and brilliant ideas objects that are immediately useful innovations that are often very practical That is what
The back of the Papophoplon is only needed if you’re using the instrument somewhere other than the location for which it was designed. It features a map of France, which shows the additional adjustment required depending on your location. In practice, find your location on the map and read the
Stop looking for noon at 2 pm — just find it! Note for non-French speakers: there is an expression in French about : “Looking for noon at 2 pm”. If you are looking for noon at 2 pm, it means you are complicating things unecessarily : looking for things that
We know that solar time differs from legal time and that this difference varies throughout the year. Are there any days when the difference is a round number: zero, one hour, or two hours? If so, where and when? The Papophoplon (see description here: theory and practice) highlights the days
World Sundial Day was on 20 March 2026, the day of the equinox. For the second year running, it provided the occasion for amajor online conference, attended by around a hundredsundial enthusiasts from all over the world. Around fifteen speakers took to the stage, and their presentations sparked fascinating questions
Going from this: a marble slab at the stonemason’s… To this : As you can see in the GIF above, the virtual Papophoplon (see here) shows 11 o’clock in solar time and the dial shows 11 o’clock. It’s very accurate! NB: I had to make a GIF because even with
Here is a Geogebra animation that allows you to visualise the equation of time due to obliquity (the tilt of the Earth on its axis of rotation).Select the day of the year and view the difference between solar time and legal time.Please note: only obliquity is simulated here.
If you do not have a physical papophoplon, you can still find out the difference between legal time (the time on your watch) and solar time.To do this, simply enter your longitude below: Please note that this tool works for locations on UTC+1. For a universal electronic Papophoplon, plese see
In this article, we explain the three adjustments made by the Papophoplon. 1. Summer time or winter time? The first difference between solar time and your watch comes from summer or winter time. The sun does not know that you set your watch forward one hour in summer. Nor does
How to convert solar time to clock time? Frustrated by looking at a sundial and finding that it doesn’t show the same time as your watch? Here’s the solution: the papophoplon allows you to synchronise your watch and sundial (and lots of other things!). How does it work (in practice)?
https://youtu.be/oUihOOhkaI8 Place the glass flat, with the eyelet facing the Sun. On the side oppposte to the Sun the shadow of the eyelet should fall on the markings on the dial. Turn the glass slightly so that the shadow of the eyelet falls within the column for the month. If
An independent consultant at your service! After fifteen years of international auditing (in England, France, the United States and Gabon), I founded FinHarmony in 2001 and made it the independent leader in IFRS standards in France, in consulting and training. In 2025, I sold FinHarmony and now offer my experience
The Sun peaks in the sky at true noon. For example, at the latitude of Bordeaux (45°N), it reaches a height of 45° on the horizon
Taking stock at sea As long as navigators keep their eyes on the coast, navigation is quite easy: you just need to find your bearings
Warning: it is not known for sure whether this instrument was actually used by the Vikings. Such an instrument would have been made of wood
There are situations in which using a magnetic compass is unreliable. This is the case inside a military vehicle (plane or tank). Indeed, the presence of continuous
Among the modern solar compasses used during the Second World War, it is undoubtedly the simplest and most effective model for this purpose. It is
Astronomical compasses were used by both sides during World War II, when other alternatives could not be used. For example, a magnetic compass can be
Finding the North without a Compass Plant a stick (gnomon) on flat ground. Locate the length of the shade throughout the day (by placing a
Plant a vertical stick in flat ground (gnomon). Locate the end of the shadow (by placing a pebble, or by planting another stick). Wait about
With a regular watch (graduated from 1 to 12) Orient the watch so that the small hand is pointing in the direction of the Sun,
Some watches have a 24-hour hand. It is normally used by travelers to keep a reference time, which is why it is often found on
To use a sun compass you must know the time, and therefore you must have a watch or a radio. So how do you find
Instructions for use This GeoGebra animation replaces the reduction tables used in astronomical navigation. Step 1: Enter your estimated position Use the first two sliders: