04 May 2025

Which time is correct and whom to thank for the clock tricks you play twice a year?

Which time is correct and whom to thank for the clock tricks you play twice a year?

Yes, we are referring to the daylight saving time (DST) or summer time, used by 70 countries in 2025. All in all, 143 countries have tried it at least once, though as you can see, many have rejected the concept. Different sources credit two Englishmen – an entomologist[=EX1] and a builder – with the idea, even though the whole story had started centuries before they lived, involved more people, and brought several reasons to adjust clock hands by season.

Ancient World and Middle Ages

8^th-4^th centuries BC, Ancient Rome

– Let’s have the highest point of the sun to define when an action happens. We call the moment when the sun reaches the highest position above the horizon noon , so other time periods during a solar day should be before noon (ante meridiem, a.m.) or after noon (post meridiem, p.m.).

3^rd century BC - 14^th century AD, Ancient Rome

– It appears Greeks have an advanced system of timekeeping. Like we do, they also use the sun but divide the daytime into twelve periods. They call each an hour.
– So how long is an hour?
– It depends on a season and your location. For instance, at our latitude (Mediterranean), an hour is short in winter and becomes 1.5 times longer in summer.
– Sounds interesting...

One hour would then last from 45 to 75 minutes for Romans. For societal purposes, they would divide a day into 16 periods and use them to schedule activities and mark important events like childbirth. The length of each period would also depend on seasonal daylight.

As you can see, candles are some of the oldest inventions which used to be an important element of daily life. And it were candles which made people to reconsider the system of timekeeping.

14^th-18^th centuries, Italy

– You know, Babylonians managed to divide the day into 60 equal parts and have been following this system for centuries now. Doesn't it sound better than our pesky system of floating hours? Year-round adjustments are stupid!
– Alright. Let's follow them. But let’s divide the day into 24 equal hours, so that each hour would also have 60 equal parts. And let’s start counting from sunset!
– Whyyy?!
– This way the 24^th hour of a day should always end with the sunset, so we will easily know how many hours we still have before there’s a need for candles again.

In the medieval times, people would go to bed soon after sunset and, of course, would not waste candles for night hours. Hence, the number of hours before dawn allowed to calculate the number of candles one could save on.

16^th century, Poland, modern-day Czech Republic and parts of Germany

– Do you know the new time system Italians have adopted?"
– Yeah, but I’ve heard them criticising the 24-hours approach for not always being practical. They’re going to make it a twice-twelve system, aren't they?
– No, not anymore. They have six-hour clocks and make it four cycles of six hours a day.
– Oh, then we can do it! Let’s adopt equal hours and sunset as the starting point from dear Italians but make it two cycles of 12 hours!

Modern History

During the 18^th century, European countries did not have a unified system of time measurement. The approaches differed in when to start counting (sunset, sunrise, midday, or midnight?), whether to make day sections equal (though the majority had already got used to equal hours by that time), and how many parts should a day and an hour have.

A known French mathematician suggested a decimal system to measure both weight and time and simplify calculations. The idea was by Jean le Rond d'Alembert. It reached the second round of discussions in 34 years, when a French attorney Claude Boniface Collignon proposed to divide a day into 10 hours, an hour into 100 minutes, a minute into 1000 seconds. Another five years after that, Jean-Charles de Borda, a French mathematician who was absolutely upset with the inconvenience and mess the time-related calculations had brought finally introduced the decimal time system where 1 day = 10 hours, 1 hour = 100 minutes, 1 minute = 100 seconds (in France only!).

1784, France

An anonymous letter is published in the French daily newspaper Journal de Paris. The writer encourages Parisians to rise earlier in the morning to be able to use natural sunlight and spend less candles. To make the process even more effective, the author also suggested ringing church bells and firing cannons at sunrise.

The letter was satirical and the author was Benjamin Franklin, then a 78-year-old American diplomat who had left the position of the United States Minister to Sweden and did not know yet he would be elected as the sixth governor of Pennsylvania.

1810, Spain

The authorities of Cádiz adjusted their meeting times for the summer and allowed private businesses to shift their opening hours depending on a season and regular daylight conditions.

Remember Cádiz is the very south of Spain where summer temperatures can feel extremely hot.

1895-1927, New Zealand

George Hudson, an Englishman who had moved to New Zealand as a child, was then 28 years old. He worked at a post office and spent afterwork hours on his hobby: collecting insects. Naturally, the hobby kept the man dependent on daylight. It did not take him long to notice that if he started work earlier in the morning despite it’s dark, his shift would end when there’s still daylight. The more George thought about it, the more benefits he found, even though he objectively saw inconveniences like altering all the clocks and making people get used to the scheme.

Hudson’s idea of a 2-hours-shift received great interest from the city of Christchurch, so in a few years he presented it in the capital. After rather long discussions, New Zealand did adopt DST in 1927, which appeared to be 11 years later than Australia and the United Kingdom (all being parts of the British Empire at the time). George Hudson was already 60 at the moment.

As for collecting insects, he nevertheless managed to create the largest private collection in New Zealand. The collection includes several thousand objects and is available at the Museum of New Zealand in Wellington.

1907, England

William Willett, another Englishman who was living in the southern suburbs of London, was on his morning horse riding walk when he noticed many people were still sleeping and thus losing daylight hours. He knew nothing about his "New Zealand’s colleague’s" efforts concerning the issue and published his own essay. At explaining the problem, William presented a solution: let’s shift the clocks gradually, by 20 minutes during four Sundays. This way, it would be possible to get 80 "extra" daylight minutes and save about £2.5 million in lighting costs, according to Willett’s calculations.

He got support from one member of parliament (Sir Robert Pearce) and the newly appointed President of the Board of Trade, Winston Churchill (then 33 y.o.) who was at the start of his political career. The idea was reviewed several times but never became a law.

Willett is said to have had golf as his another hobby, and it, of course, was a pity to cut the game at dusk knowing there were almost two hours missed in the morning.

1908, Canada

The municipality of Thunder Bay (then Port Arthur) in Ontario became the first region in the world to actually introduce DST as we know it today. There were no scandals, no lobbying, but local citizens decided to try the concept. Six years later, the city of Regina in Saskatchewan joined Thunder Bay, and in another two years the cities of Winnipeg and Brandon in Manitoba also adjusted their clocks for one hour – officially, a week earlier than some European countries.

1916, Europe

Modern-day Germany, Austria, Hungary, the UK, Italy, France, Belgium, the Netherlands, Denmark, Norway, Sweden, Czech Republic, Slovakia, and Poland adopted DST as a law within few weeks. The fast-track was reasoned by the First World War being on for two years by that time. The countries aimed to save on artificial lighting as well as on coal. The latter was the main fuel while front-line necessities were the first priority.

When the war ended, many countries returned to their standard time – until 1940s, for it being wartime again (then the concept of double DST[=EX2] was introduced in some countries), and again until 1970s, for the energy crisis in Europe.

More about time

Live time to decimal time converter – time is simply about maths😉

On Seasonal Time – text of the speech by George Hudson which he presented in Wellington to argue for the DST implementation (sourced from the Royal Society of New Zealand)

A Chronicle of Timekeeping – a historical overview of evolution of time measurement, by William J. H. Andrewes

[=EX1] a person who studies insects [=EX2] a time system where clocks are set two hours ahead of standard time