Thread: Why aren't there thirteen through twenty-four o'clock?

Why do we split a day into halves and repeat the times? If every hour had its own title, then there would be no confusion or accidents over replacing ante meridiem with post meridiem, and vice versa.

Originally Posted by Theresa

Why do we split a day into halves and repeat the times? If every hour had its own title, then there would be no confusion or accidents over replacing ante meridiem with post meridiem, and vice versa.

It originally evolved from the idea of dividing the day between daytime and night time. The Romans adopted this from others, and likely passed it on. There was a time when some people used the 12 hr clock and some used the 24 hr clock, but somewhere along the line, the 12 hr clock became common usage. The 24 hr clock is in use today in certain areas, such as the military and aviation, to avoid just those confusions between AM and PM you mentioned.

Thank you. I know. The question is why the twelve hour clock is preferred, since the twenty-four hour one is simpler. How could the standard clock of today even exist if its origin is the separation of night and day? Many post meridiem hours occur during sunlight.

Just think in terms of early crude mechanical clocks. It's easier to make a 12. A 24 demands more precision, more divisions. A 12 hour is easier to see from a distance on a clock tower, the most common clock most of the people used in those days.

Etc. etc, etc.

Originally Posted by Theresa

If every hour had its own title, then there would be no confusion or accidents over replacing ante meridiem with post meridiem, and vice versa.

Many countries, and organizations like the US military, do just that.

Great points, doitright! Thank you.

Originally Posted by Theresa

Why do we split a day into halves and repeat the times? If every hour had its own title, then there would be no confusion or accidents over replacing ante meridiem with post meridiem, and vice versa.

if every hour had to be named there would be an extra hour having to be added for your memory to store that additional information, process it into every segment of your time and produce the output that way.

in which case there would actually be a necessity for a thirteenth hour on the clock.

Oh, GreenGlobeAward, how difficult would it be? As I've pointed out, the matter would be faster and easier to process since there would only be one seventeen o' clock instead of two five o' clocks. Your joke isn't bad, though.

I believe the whole thing came from Ancient Egyptian sundials and them counting in base 12. I guess it just carried on for simplicity. Probably why we use the Gregorian calendar and correct it every 4 years, rather than use the Mayan calendar and have no idea what day it is.

I believe the whole thing came from Ancient Egyptian sundials and them counting in base 12. I guess it just carried on for simplicity. Probably why we use the Gregorian calendar and correct it every 4 years, rather than use the Mayan calendar and have no idea what day it is.

Oh, yes, I have forgotten about the sundials. That's a smart connection, AnthonyChan! Thank you. I'm sure that we're all very grateful for the Gregorian calendar.