Clocks with Roman numerals have ‘4’ as ‘IV,’ while others use ‘IIII’. Why?
There is no a definitive answer. There are a handful of competing theories and one of them might just be the correct one.
Let’s look at a few.
When Roman numerals were used by the Roman Empire, the name of the Romans’ supreme deity, Jupiter, was spelled as IVPPITER in Latin. Reluctant to put a god’s name on a sundial IIII became the preferred representation of four.
IV, instead of IIII, which represents four didn’t become the standard until well after the fall of the Roman Empire. It’s likely, then, that IIII was used on sundials (and everywhere else) simply because that was accepted convention at the time, and not for fear of divine retribution.
In the years to follow every clock-maker had to decide whether to adopt IV because it was the new standard, or hang onto the traditional IIII.
IIII might have stuck around because it’s easily recognizable as four. IV involves a little math. it’s a simple subtraction operation. Though subtractive notations really caught on in the Middle Ages, the majority of people were not literate or numerate. Subtraction involved conscious thought. IV and VI might also have been easily confused by the uneducated.
Using IIII may have also made work a little easier for certain clock makers. If you’re making a clock where the numerals are cut from metal and affixed to the face, using IIII means you’ll need twenty I’s, four V’s, and four X’s. That’s one mold with a V, five I’s, and an X cast four times. With an IV, you’d need seventeen I’s, five V’s, and four X’s, requiring several molds in different configurations.
King Louis XIV of France preferred IIII over IV, perhaps for the same reasons Jupiter would not want two letters from his name on a sundial, and so ordered his clock-makers to use the former. Some later clock-makers followed the tradition, and others did not. Other monarchs might have felt the same way, and IIII was used also in areas where there was no king with an IV in his title to object to the subtractive notation.
And lastly IIII is that it creates more visual symmetry with the VIII opposite it on the clock face than IV does. Using IIII also means that only I is seen the first four hour markings on the, V is only seen in the next four markings, and X is seen only in the last four markings, creating radial symmetry.
Which theory do you prefer?