Expressed as Roman numerals, the first twelve numbers are usually given as I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII. However, on many clock faces, when the numbers on the dial are in Roman numerals, IIII replaces IV.
In Pittsburgh, for example, the ornate Kaufmann's clock (above) at the corner of Smithfield Street and Fifth Avenue, shows IIII instead of IV.
There are many stories about why IIII appears so often as a replacement for IV on clocks but no definitive explanation. The tradition apparently has a long history and may even go back to sundials.
A large entrance clock created for Thomas Jefferson at his home Monticello features IIII instead of IV.
I tend to like the explanations that appeal to symmetry. Using IIII instead of IV means that the first four numbers—I, II, III, IIII—require only I; the next four—V, VI, VII, VIII—only I and V; and the final four—IX, X, XI, XII—only I and X.
A clock in Portland, Oregon.
Some also argue that, on a clock face, IIII is a better balance than IV for the VIII that appears across from it.
You can also count up how many of each character you need to create all the numbers. In the IIII case, the totals are 20 I's, 4 V's, and 4 X's (all even numbers), versus 17 I's, 5 V's, and 4 X's.
Some clocks do use IV instead of IIII, like the clock (above) in Pittsburgh's Market Square. The most famous example may be Big Ben in London.
The clock atop the tower at the University of Texas in Austin features IV instead of IIII.
So, what happens with Roman numerals on a 24-hour clock? What about sundials?
Photos by I. Peterson