The Secret of the Time Measurement 2: Hourglass

Lucy Bennett | 26. 2. 2019

Since time immemorial people were trying to decipher a mystery of the time and master horological art. Before the invention of a clock as we know it today, there were many other inventions as well. Which ones? Next chapter of our series about the beginning of clock history is here. 

One of few ways our ancestors determinate the time was by using a hourglass and it was a pretty accurate way. 

When was the hourglass invented?

Its origin and age is unclear. Its existance was proven in 14th century, but some theories argue that is was used in 11th century already while sailing and other ones like to argue that it was invented even in 8th century (or maybe even sooner that that). 

How does it work?

Unlike a sundial, which depends on the Sun movement, the hourglass works thanks to gravity. It consist of two glass vessels, which are connected by a narrow tube. Sand is gradually poured from the top vessel into the bottom one. Once all the sand is gone the hourglass has to be turned upside down and the whole process starts again. Usually it is able to measure an hour, but sometimes it can be adjust to measure even longer or shorter period of time. But because it is not able to work uninterrupted and shows the exact time it is used maily for measuring only short period of time. Today we can easily replace it by using a good quality watch with a stopwatch or a timer, but that way we impoverish our household of this impressive ornament.

What is it made of?

Nowadays it could be made of glass or plastic. For its frame is usually used wood, metal or other materials. The earliest hourglasses were made of metal or wood and were the most often filled with sand and later even other compounds were used – for example crushed marble, burnt eggshel and zinc or lead dust. Over time people tried more and more compounds to test which material is the best for flowing evenly.

How to make it yourself?

  • First of all you have to thoroughly prepare pouring mixture so it is as finest as possible (has to be clean of impurities, washed in the water and then dried for many weeks and after that the sand needs to be sifted through sieves many times.
  • And then a clockmaker will create a high quality bulbs, measure them and test their quality. At this moment he will prepare parts for the frame, in which the bulbs are going to be fitted together with all the decorative elements.
  • Clockmaker has to know the time period the hourglass is going to measure out and accourding that prepare relevant amoung of mixture. Particular weight is set in advance, althought you still have to punctually weight and measure, test and sometimes even observe for hours so the hourglass is as precise as possible.
  • Then the hourglass needs to be assembled – mixture pour into a one of the bulbs, seal the bulbs with resin and connect frame parts with glass part. The hourglass making takes a couple of days (when the mixture is ready to use).


Water clock

Precursor of the hourglass was water clock, which is probably originally from the Middle East. Its history starts in 14th (or quite possibly in 15th century) BC. They were used in Acient Egypt, Babylon and then later in Greece. It was called Clesydra, which means "water thief" in Greek. In Middle Ages it was a popular gift for monarchs. Same as hourglass also water clock measured only a certain time period. Originally it was a vessel with a small opening at the bottom and guidelines on the vessel were showing how much time passed. They got more and more advanced, but their main disadvantage was that the lenght of an hour changed during the year. Nowadays water clocks are used as a reminders of the past and also as a decoration. 

And at the end other interesting inventions


Are you familiar with astrolabe? It is an eye catching device. This astronomical device was mainly used by voyagers, surveyors and astrologers. It was able to determine star locations, time according local longitude and it was made for calculating distances. It has been used since Antiquity and its principals were even used on Astrological clock in Prague.

Nowadays, instead of a similar device, we could use a watch with GPS or compass. And why not to just get the one which have not only GPS, but also a barometr, a pedometr and even shows the world times? Popular watch brands that combine many of these useful features are for example Casio G-Shock collection or also some sports collections from Festina.

In our next (and also final) part of our series you will learn something about mechanical clock and you can see for yourself the unbelievable progress and development which go along with humanity since the beginning of time...