Things, which – as I assume – are hanging on the walls of houses of most of us, are not really clocks! In truth these are half-clocks (sic!). Full, the most correct in its form clock counts down 24 hours at one turn (not, as we are accustomed to, 12).
24-hours numbering is not – thankfully! – fully forgotten. The fact remains since the end of the XVIth century half-clocks began to effectively replace full ones, but just take a look at electronic clocks with numeral display… What’s more, as you think about it, the 12-hour sistem dominated most of countries in verbal description of the time, but a record quite often remains faithful to medieval traditions.
Video below ilustrates what I am basically talking about 🙂
The advantages of full clocks over half-clocks are described here.