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Huygens’s pendulum clock gave the world accurate time

Dutch time standardized in 1909

Tags: Excerpts from the Windmill

LEYDENM – Time is of the essence in modern life but keeping track of it is very difficult if one town is out of step with time in another town down the road. That was the situation the Dutch railways faced a century ago when drawing up their schedules. For example, time in the Twente town of Enschede was 20 minutes earlier than that in The Hague. The difference may not have mattered when the Dutch traveled from place to place by coach or canal barge, but the rise of a much faster national railway system with a comprehensive train schedule required better regulation.

Astronomer Rob van Gent, a former conservator at Leyden’s Museum Boerhaave where he served for a decade, recently revisited the history of timekeeping in the Low Countries and the development of time measuring instruments. The standardization of Dutch time occurred a century ago in May 1909, when the Second Chamber passed a law introduced by the coalition cabinet of Theodorus Heemskerk Jzn.

Van Gent, who now is working on a joint project for the Utrecht Research Program in the History of Cartography (Explokart) and the Astronomical Institute of Utrecht on the history of Dutch celestial cartography, has been interested in time measurement since his high school days. Muslims in the Netherlands, who were concerned about the precise starting time of their Ramadan, requested this information from the Leyden Observatory. The request was passed on to Van Gent, who immersed himself in the subject.

Tower clocks

How did people regulate their daily life without clocks and other time pieces? According to Van Gent, the daily pattern in people’s life for centuries was measured by the cycle of the sun. People could check the stars and the moon if they needed to know how far the night had gone, although this gave problems during spells of cloudy weather.

With the invention of clocks in the medieval era, time keeping became far more precise and also more accessible. Church towers in the cities were first outfitted with clocks. Still, the time needed to be checked regularly, which was one of the many duties of a ‘koster,’the all-round helper of the priest. If the sun dial had reached its highest point, it would be 12:00 noon. Even with the help of the tower clock, it remained difficult to double check time if the weather was cloudy. The average person was not affected by finetuning the time of day in the tower, since the clock was a sufficient reference point for the vast majority of the people on the street. The bells in the towers regularly announced the time to those at a distance.

The next innovation in time keeping came in 1656 when mathematician, astronomer and phycisist Christiaan Huygens finetuned his pendulum clock which rendered dependence on the sun dial obsolete. The accuracy of time since then was a questions of mere seconds.

Berlin time zone

The Netherlands was somewhat late in regulating its standardization of time, because other European countries had preceded it. The problem was political, as some wanted to conform to the London time zone, while others wanted to join the Berlin zone. Instead, the Amsterdam time zone was chose. It had been developed earlier by the railways to regulate their schedules.

That the Netherlands now uses the Berlin zone dates from the German occupation. Immediately after the invasion, the Germans switched the Netherlands to its system, including its summer time schedule. Since the Germans were already on summertime, the Dutch were forced to advance their clocks a full two hours in May 1940. The Dutch government never reversed that decision after the Libration in 1945.