A Short History of Daylight Saving Time

By way of introduction

If we open the 2005 postal almanac, we find all kinds of information: public holidays, moon phases, school breaks, computus data, sunrise and moonrise times... But nothing, not a word, about daylight-saving change dates. You would almost think the Roman indiction (which is practically useless) matters more than those two yearly clock changes.

And yet that change matters. Twice a year, it sends us looking for every clock in the house to reset it. It has fueled endless debate. Some are in favor, others are against.

In this page, we will follow the history of what has become a tradition and try to understand why it appeared and why it still exists.

We will not take sides, even if some observations do point toward fairly clear conclusions.

Our focus will be the history of daylight saving time in France, with a few words on other countries as well.

A very old idea

The idea dates back to 1784. It came from Benjamin Franklin, who presented it in a slightly tongue-in-cheek letter sent to the Journal de Paris, published on 26 April 1784.

Born in Boston, Benjamin Franklin first worked as a printer-journalist and published the New England Courant with his brother, then the Pennsylvania Gazette in Philadelphia. He also edited an almanac in which, under the pseudonym Poor Richard, he wrote sayings, maxims and practical advice. He was also interested in science and invented the lightning rod.

The young United States sent him to Paris to secure the support of the King of France. The mission succeeded: he won over the enlightened circles of the kingdom and was received by Louis XVI, who recognized the United States. He returned to America in 1785, covered in glory.

That “letter” originally came from a more serious text, An Economical Project, about natural energy savings. He rewrote part of it as a favor to Antoine Alexis-Francois Cadet de Vaux, editor of the Journal de Paris, who wanted a version accessible to his readers.

He begins by describing a demonstration he attended the day before of a new oil lamp. He then recounts the discussion that followed about the ratio between oil consumed and light produced.

With that in mind, he went home and fell asleep around 3 or 4 a.m. A noise woke him around 6 a.m., and he was surprised by the brightness in his room. He first thought it came from those famous lamps, but realized it was the rays of the rising sun. Reading an almanac confirmed that sunrise would keep coming earlier until late June.

“This event made me think of more serious and important matters...”

In short, Franklin concluded that Paris could save an immense sum each year.

He also proposed practical measures:

1. Tax residents one louis per window if they keep shutters closed.
2. Ration candles to one pound per family per week.
3. Stop all traffic after sunset except doctors, surgeons and midwives.
4. Ring church bells (and fire cannons if needed) at sunrise to wake everyone.

Replace cannon fire with an alarm clock set earlier, and summer time is basically born. Still, Franklin's plan was to wake people earlier, not to shift official clock time.

The idea, stripped of its eccentric side, was revived in 1907 by William Willett (1857-1915), an English entrepreneur.

Willett's proposal did involve moving clocks forward and backward. In his pamphlet Waste of Daylight, he explained a process in four Sunday steps at 2 a.m. in April and September, 20 minutes each Sunday. He chose 2 a.m. because it disturbed train traffic the least.

His goal was twofold:

• Spend leisure time in daylight.
• Save energy otherwise used for artificial lighting.

Energy savings

Spending more waking time in sunlight was the goal of both Franklin and Willett.

Let us look at France in 2005.

Between late March and late October, we lose morning daylight and gain evening daylight. Strictly speaking, total daylight duration is the same for any given day whether summer time is applied or not, but that daylight shifts toward hours when people are awake.

The objective, however, was never tanning. It was energy savings: candles for Franklin, coal electricity for Willett, then later oil.

The official line in France long remained that summer time, reintroduced after the 1974 oil shock, reduced evening lighting demand and therefore energy use.

Whether fully true or not, we are not taking a political position here.

Summer time / winter time: the best wording?

We say “summer time”, fair enough. But “winter time” is really just a return to standard time. In practice, we enter summer time and exit summer time.

In France, even so-called “winter legal time” is already one hour ahead of UTC for our meridian.

English uses Daylight Saving Time, which is clearer than many local expressions.

Personally, I prefer simple wording: standard time / advanced time.

Origin and brief timeline in a few countries

Europe

Since 2001, entry into summer time has taken place on the last Sunday in March, and exit on the last Sunday in October.

United Kingdom

As this table shows, implementation was not straightforward and decisions were strongly tied to economic conditions, especially around the two world wars.

France

It is sometimes said that the summer-time/winter-time system began in France in 1976 under Valéry Giscard d'Estaing. In reality it is far older: it dates to 1916, initiated by André Honnorat.

The law moving legal time forward by one hour to reduce public energy use was eventually passed on 19 March 1917, by 291 votes to 177.

Below is the evolution of the French system from the beginning (changes shown in red in the original source):

Conclusion

We could multiply examples, but it would be long and not very useful.

The examples above are enough to show that one major trigger was wartime context, and that many countries dropped DST between war periods (France being a notable exception).

In the United States, for example, DST was used in 1918-1919, then dropped, then reintroduced from 09/02/1942 to 30/09/1945. From 1946 to 1966, states and cities were free to apply it or not. In 1966, a uniform federal framework was applied (with specific exceptions in 1974 and 1975). In 1986, the start moved to the first Sunday in April.

A quick word on Switzerland (which did not share the same wartime constraints):

• It applied summer time in 1941 and 1942.
• From 1981 to 1995, it used the last Sunday of March / last Sunday of September pattern.
• Since 1996, it has aligned with EU rules.

Advanced time everywhere in the world?

If summer/winter time is meant to align human activity with sunlight during part of the year, can we use it everywhere?

A bit of basic astronomy helps.

At the equator, day length is almost constant all year (around 12 hours), and sunrise/sunset change very little.

As latitude increases, the gap between the longest and shortest day increases. Around the Tropic of Cancer the gap is about three hours. At the Arctic Circle, the sun may not set at summer solstice and winter daylight can be very short.

These day-length changes alone do not answer the practical question. The key issue is evening light during waking hours.

At the Tropic of Cancer, sunset is roughly around 19:40 in summer and 18:00 in winter. A one-hour shift can make sense there. Moving from that latitude toward the equator, it becomes less useful.

So, broadly, advanced-time systems are more relevant between the Tropic of Cancer and the Arctic Circle.

The same reasoning applies in the Southern Hemisphere with seasons reversed (typically October to March).

Countries applying a summer/winter time system are shown in red on the map below.

This map is approximate. Note: several countries have changed their policy since then (Russia, Egypt, etc.).