It’s hard to imagine chess without a chess clock these days but we often forget that when chess was first invented, timers weren’t a part of it. When chess was first invented, matches used to last even for days.
Eventually time limits were established and chess clocks were introduced. The first official record of a chess clock dates back to 1883, when a mechanical timing device had been invented by Fattorini & Sons of Bradford in London.
The first prototype of a chess clock looked exactly like the ones today - two identical clocks set on opposite ends of a balance beam. The rules were the same too, when one player finished his move, he stopped its time and started the opponent’s clock.