More than you might think
It turns out that analog clocks have more in common with Roman mythology than you thought. If you’ve ever looked at the dial on a Roman numeral analog clock and wondered why the notation for ‘4’ was ‘IIII’ instead of the subtractive “IV” that we’ve come to know, then read on!
It may come as no surprise that the Roman numeral dial was first used by—you guessed it—the Roman Empire. Of course, the people of the Roman Empire weren't quite using the spring-driven analog clock movements of today (which wasn’t invented until the 15th century, and even then, it took awhile before accurate and self-regulating spring-driven movements were invented). Instead, sundials were used.
Let’s take a side step here and talk mythology. The Roman Empire followed the Roman religion and the king of the gods was Jupiter. Jupiter, as the king of the gods, was the god of the sky and thunder. The Romans believed that it was through Jupiter that they had achieved supremacy in their conquest of Europe and was ‘the fount of the auspices upon which the relationship of the city with the gods rested.’ As the king, he was the deity that the Roman people prayed to the most—and whose wrath they feared the most. It’s also important to note that in Latin, the Roman’s official language, ‘Jupiter’ was spelled ‘IVPPITER’ and was abbreviated as ‘IV’. Look familiar?
So, in order to avoid accidentally calling on the supreme god and triggering his wrath, the Romans thought it would be best to just avoid using his name altogether on sundials or in accounting books, preferring instead to use the notation IIII, and one theory is that clock and watchmakers have just stuck with this tradition, especially as the metal work involved for using ‘IIII’ would’ve been significantly easier versus needing to create yet another mold for ‘4’.
Some critics of this theory do like to point out that subtractive notation (where ‘IV’ means ‘4’ because it is ‘I’ less than ‘V’) wasn’t the standard until well after the fall of the Western Roman Empire, so ‘IIII’ was simply the proper notation to use at the time and had nothing to do with divine retribution. Still others say that the tradition was continued with other monarchs throughout history such as King Louis XIV of France, who demanded that his clockmakers used the ‘IIII’ so as to not deride from his significance.
Of course, maybe the clockmakers used the ‘IIII’ notation instead of ‘IV’ simply because it looked nicer to them.
What do you think? Which theory do you believe is the most accurate? Do you have a different theory?