Thursday, April 9, 2015

Clocktower: IIII for four o'clock

Clocktower clock, Maynard, MA
Admire the clock faces on the Clocktower clock. On each, four o'clock is designated by a Roman numeral "IIII." Which begs the question, why not "IV?"

The best-supported answer is that Romans did not always use Roman numerals the way we do. We use a subtractive mode (IV instead of IIII, IX instead of VIIII), which became the standard in Europe long after the decline and fall of the Roman Empire. IIII was used on Roman era sundials, and appears to have been carried forward in time to Renaissance era clocks.

Another theory is that IIII provides more visual symmetry for the clock face, with clock makers conforming to this practice by design. With IIII for four and VIII for eight, the two numbers opposing each other are of similar width. Jibing with this concept is the fact that the same clocks that do not use subtractive mode for four do use it for nine (IX), creating a closer visual match for III on the other side. Finally, using IIII means that the first third of the clock face has I's, the next third has V's and the final third has X's. Internet searching yields a few other explanations, but these two - tradition and symmetry - make the most sense.

Clock faces incorporate other traditions. When the Hindu-Arabic numbering system (1,2,3,4,5...) is used, all numbers are oriented to be top end up when the face is viewed vertically, but Roman numerals (I,II,III,IIII,V...) are oriented to be top end up from the viewpoint of the center of the face, facing outward. Was this to be radially symmetric or functional? Likely the latter, carried forward in time by tradition. Think of walking up to a sundial; with your back to the sun the shadow cast by the upright will be opposite you and the number it points to will be right side up.

Clock hands proceed clockwise. In the Northern hemisphere a horizontal sundial will have twelve o'clock oriented due north. As the sun's position in the sky shifts from east to south to west the shadow will move around the top arc of the face left to right. When mechanical clocks were perfected in Europe the sundial's movement was mimicked for its familiarity. Hence, the worldwide convention is clockwise. (It is possible to buy novelty clocks that run counterclockwise.)

If sundials had spread to the rest of the world from the southern hemisphere then the sun's shadow would have proceeded across the top arc from right to left and mechanical clocks might well have followed that tradition to end up going the opposite direction of what we know accept. (Of course, this manner of movement would have been called "clockwise.")

The earliest mechanical clocks did not have hands or faces. In Catholic Europe, these devices were installed in church towers to automate ringing of bells meant to signify daily calls to prayer. Hours were signified by bells. Time was audible rather than visual.

Clocktower clock face from inside the clock
External clock faces and hands were added once clock mechanisms became more accurate. Standards of design now call for a short, stout hour hand, a longer, thinner minute hand and a very thin second hand, often a different color. Days have 24 hours but clock faces have only 12, mostly because a clock face with 24 numbers would be too crowded. Smart watches keep digital time (either 12- or 24-hour) but can display analog faces. The French Revolution brought the world the metric system of measuring distance and weight, but the metric clock (10 hours, 100 minutes per hour, 100 seconds per minute) was an epic fail.

Time used to be local. Starting in the 1800s, problems were caused by railroads traveling so far in a day as to be servicing cities each maintaining its own local time. The solution, reached in 1883, was to agree on dividing the U.S. into four time zones, with concord on accurate time within and between zones made possible by telegraph.  

Close-up of gears at the clock face
In print advertising for watches and clocks it is traditional to show the time as 10:10. Maynard's Town Seal shows the Clocktower clock at 12:10 to indicate the more than century long tradition - abandoned in 2011 - of the fire department conducting a daily test of the fire horn at ten minutes after noon.

I am really sad that the fire station's fire horn no longer sounds at 12:10. I found that 125 dB electric horns and a control box could be purchased from SENTRY SIREN and installed at the mill complex, perhaps on the Clocktower or chimney.   


  1. I've noticed this! I live right near the clocktower and I remember I first noticed that IIII instead of IV during the holiday season a couple of years ago when I saw the clock faces change to festive colors for the first time (I had moved to Maynard a few months prior to then).

    Very interesting stuff!

    - L

  2. oh that's great info i never would have guessed thanks