Telling Time by Candle Light?

Have you ever wondered about how people knew when to wake up before they had alarm clocks? Historically, people have used various types of clocks to keep track of time, from sun dials to pendulum-driven grandfather clocks, to analog and digital wristwatches, to smartphones and health fit bands. However, if we look back several centuries, we might be surprised to learn that candles were used to track time. Of course, candles have been used for various purposes, such as illuminating places, birthday cakes, and enjoying romantic dinners, but tracking time? Setting alarms?

It is difficult to determine the exact origin of the candle clocks. The first reference can be found in a Chinese poem written by a poet named You Jiangu that dates back to 520 AD. He spoke of using six uniform candles having the same weight and thickness and 12 inches in height.

An inch of the candle would get depleted in 20 minutes and so a candle would last for 4 hours, The candles were kept in enclosed structures to ensure the flame was not easily disrupted by winds or drafts.

In ancient England, King Alfred the Great used candle clocks to track time. The candles were marked to ensure incremental measurements of time could be tracked. In medieval churches, they were often utilized to schedule prayers, services, and bell ringing.

In urban settings, other options for those seeking to wake up early were factory whistles, street criers, and church chimes.

Setting Alarms in Candle Clocks:

Nails were inserted at specifically marked heights of the candle, which was then placed on a metal plate. As the candle burned down, the nails would fall, making a tinkling, metallic “alarm” sound.

The Advantages of Candle Clocks:

Candles were used extensively when there were a limited number of mechanical clocks. And even after the arrival of the latter, they were still used in many places. Here are some inherent benefits of candle clocks:

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• As the wax melting rate is quite constant, the time measured by these clocks was pretty accurate
• They proved to be a worthy alternative to the ancient methods of watching the sun and moon to track time. Both the moon and the sun were hidden on cloudy days and nights. In such situations, using candle clocks was a practical alternative
• Using candles was a relatively cheap method to measure time given that mechanical clocks were rare and extremely expensive

The Drawbacks of Candle Clocks:

Candle clocks, while easy to use, had their drawbacks for tracking time.

• They are only useful for measuring an interval of time and can’t be used to pinpoint the exact time in a day
• The candles may get blown out by strong gusts of wind
• If the candles are blown out before reaching a mark, it’s hard to figure out the amount of time gone by
• Burning unattended candles is inherently risky because of the fire hazard

So, the next time your smart phone’s alarm wakes you, ponder how your ancestors used such ingenious methods of making sure they were “on time.”