Semaphore flags - School of Cipher

about 10 minutes no cutting needed if you use tea towels makes a working machine

What you need

Two garden canes, dowels or wooden spoons

Two tea towels, or the printed flags on card

Sticky tape

A friend far enough away to need it

How to build it

Make the flagsTape a cloth to each stick along one edge. Different colours if you can, so the arms are easy to tell apart.

Stand where they can see youAcross a garden, a hall or a street. Far enough that shouting is annoying.

Hold each arm in one of eight placesStraight down, low, straight out, high, straight up, and the same on the other side.

Rest between lettersBoth arms straight down means a gap. Without it, letters run together.

Send slowly and waitHold each letter still for two seconds. Semaphore is read when the flags stop, not while they move.

Keep the sticks away from faces and windows, and give yourself an arm’s length of space in every direction before you start.

The template

Print this at 100 per cent, not fit to page, or the sizes will be wrong. The ruler line below tells you whether it printed correctly.

The bar above should measure exactly 10 centimetres. If it does not, your printer has shrunk the page.

Now send something

Send your friend’s name. Then try it from opposite ends of a park, where nothing else would carry.

Where it comes from

The Napoleonic wars onward

Faster than a horse

Before flags there were towers with great moving arms, and a message could cross France in minutes rather than days. Hand-held flags brought the same alphabet down to two arms and two cloths. It was standard at sea for a century and is still used between ships that would rather not broadcast a radio signal.

Why it works

Eight positions for each arm, two arms, and enough combinations for the alphabet. It is read when the flags stop, not while they move, which is why holding each letter still matters more than speed.

When it goes wrong

It usually does, the first time. Almost always one of these.

Nobody can read youYou are moving too fast. Hold each letter still for two seconds; it is read when the flags stop.

Letters run togetherDrop both arms straight down between letters. That gap is part of the alphabet.

Where to go next

The alphabet, arm by arm Back to Make