– (Legia Duque/)
QUESTION Raine Castro, Boa Vista, PR
The sundial, humanity’s first timekeeping technology, appeared around 2000 BC and was calibrated at sunrise and sunset. It worked like this: a obelisk, the position of the first shadow of the day and the last before nightfall was marked on the ground. Afterwards, this arc was divided between the marks in 12 intervals equidistant: each was a time of day. At night, “time was lost”.
Over time, other technologies were created to try to measure time more accurately. That is, long before the mechanical clock, “invented” in the Middle Ages, there were already ways of knowing the time. Each mechanism defined the tuning of the next mechanism, until we reached the current epoch. Check out five great moments from this story:
1) Water in the basin
ERA 16th century BC
An Egyptian invention, water clocks were sets of perforated basins mounted under a stream of water. To calibrate, the water flow was activated at the first light of the day and, from then on, a sundial was used to create time marks inside the basins. It worked night and day.
2) Hypnotic Ticking
ERA 14th century
In Europe, the Church encouraged monks and artisans to create a pendulum clock. The first ones already marked minutes and were calibrated based on water clocks. But they were delayed 15 minutes a day, so they were readjusted by sunrise every Saturday.
3) Personal watch
ERA 16th century
The first portable clocks only had an hour hand and worked with winding, given by means of a key. To calibrate them, watchmakers used large grandfather clocks. The winding mechanism prevailed until the 20th century.
4) Crystalline Revolution
ERA 1928
Canadian Warren Marrison discovers that quartz crystals excited by electricity vibrate more regularly than winding mechanisms. It was enough to synchronize the prototype with winding clocks and that’s it: quartz clocks only delay 1 second every 30 years.
5) Atomic precision
ERA 1948
Researchers realized that the frequency emitted by electrons from Cesium 133 atoms was more regular than the frequency of quartz – it delays one second every 30 million years. Atomic clocks appeared, which today are used to calibrate all the others.
CONSULTANCY William JH Andrewes, specialist in the history of watches
SOURCES Book Time’s Pendulum: From Sundials to Atomic Clocksby Ellen Barnett, and The History of Clocks & Watchesby Eric Bruton