I started an argument on Blue's!!!
Yippi!!!... or...

I was an archaeology student for a couple of years and... Well, all of this stuff 'bout clock faces looking balanced and stuff might be right, don't know much 'bout clock-face making theory... Anyway, the additive way of writing roman numerals (that is, 'IIII') is the older form. The substractive writing (that is 'IV') was developed later.
Supposedly because there's less to write. (Remember, those ppl used to carve in stone. For those of you who haven't tried it, it's hard work; even a small saving in work is gonna seem like a big one) After that, the two methods were both used, but mostly the substractive.

Edit: Ok, so mr Blue has already covered all of this stuff...
I even vaguely remember that 'IIXX' business from one of my textbooks, although I couldn't possibly be bothered to dig it out right now...
This comment was edited on Aug 12, 18:27.