Once upon a time, when people was asked to turn off minute repeater... instead than mobile phones!
In the darkness of theatres, aristocrats waited for the end of the opera keeping the hour under control through striking or repeater mechanisms of their watches. In this way, the music was unfortunately interrupted very often, annoying the truly passionates.
Among them was King of Saxony, Frederick Augustus II, who decided to solve this pestering issue with his authority: the use of striking mechanism was forbidden within the Dresden theatre. The hour would have been indicated by a clock placed over the stage, big enough to be red from all the seats. This clock was realized on 1842 by Johann Christian Friedrich Gutkaes, court watchmaker, and his trainee, Ferdinand A. Lange.
The smart technical solution to reach the maximum readability was the digital hour indication: two twin rotating disks signed the hours and the minutes. The great dimension of the numbers, needed to be as clear as possible, fixed a maximum diameter for the disks, and consequently a maximum set of number to be shown. This is why the clock indicated the hours and the minutes.. but the latter only in intervals of five minutes. Easy to understand why this clock, unfortunately destroyed by a fire, is today better known as the “Five minutes clock”.