Fun with flags: take two

[This is the second part of this article.]

There are two separate motives behind use of flags. First one is marking, and the second one is communication. Although we usually see the first one as a dominant one, in this antifeuilleton we will focus on the second one: how to communicate using flags? Two well-known ways are flag semaphore and maritime signal flags. Both means of communication are used on ships, so you can imagine being aboard a ship, boat or a raft while reading this article.

Flag semaphore is like a sign language: person sending the message holds two flags in their hands and the location of arms (flags) denotes the letter being transferred currently. This position, for instance

is letter N, while

is the letter D. Put one over the other – what do you get? The international peace sign! That was the idea behind the sign, actually: letters ND stand for Nuclear Disarmament.

Now, if we want to reduce the hand-waving and allow a message on a ship to be displayed for a longer time period, we have the colourful maritime signal flags. You can see them on the mainland as well, Paul & Shark jackets, for instance. If you have a P&S jacket somewhere near you, check the ribbon on the inside, the one containing a sequence of flags from this alphabet:

(if it doesn’t say what you’d expect it to say, you might have bought a fake P&S jacket, check the possibility of returning it to the shop.)

These flags are usually found hanging on a string above the ship’s deck (you’ll find them in a box on every ship, just like a reflective triangle in a car. Every ship having them as a standard equipment led to these flags becoming an important factor in 1945. After the capitulation of Japan and Germany, the Allies forbid the use of their flags. However, there cannot be a ship at the sea without a flag (the first use of a flag is marking!) so there had to be a solution for the ships at distant seas. It couldn’t be a random signal flag either, because everyone would simply think it’s a signal flag. What if we make a pennant out of a signal flag, by cutting a triangle from the side (swallow’s tail)? That would make it different than the signal flags and make it appropriate as a marking flag. Flags A and B already have swallow’s tail ending, so the first one that could have been used was flag C (with the triangular ending, it became Pennant-C) and Germany started using it at the sea. Okinawa got D, and Japan got E pennant.

The only non-rectangular national flag in the world looks like a pennant as well: the national flag of Nepal. Mathematicians love the Article 5 of the Constitution of Nepal, as it defines the geometric construction of the flag in a strict mathematical fashion. Try the construction on your own, it’s fun (with flags)!

The next antifeuilleton will continue with the geometric motif, but we’ll bring in the freemasons as well in the story “Secret division plans.”

[This is the fifith article in a series of ten articles to be published over the course of a few weeks.]