Morse Code

Do what Vail did — count, then assign.

1. Take a page of ordinary English and tally how often each letter appears.
2. Rank the letters from commonest to rarest.
3. Assign your own codes: one element to the top two letters, two elements to the next four, and so on.

Five durations carry the whole system.

1. A dot is one unit.
2. A dash is three units.
3. The gap between elements inside a letter is one unit.
4. The gap between letters is three units.
5. The gap between words is seven units.

Prove that the code is independent of the channel.

1. Tap a short message on a table with a pencil.
2. Send the same message by covering and uncovering a lamp.
3. Send it by voice, saying dit and dah.
4. Send it by squeezing a partner's hand.

Put a number on what the frequency weighting buys.

1. Encode a 100-letter passage in Morse and count the total time units.
2. Now encode the same passage giving EVERY letter the same five-element length, as Baudot does.
3. Compare the totals.

Alfred Vail and Samuel Morse developed the code around 1838; the frequency weighting is generally credited to Vail. The original American Morse used internal spaces within some letters, which machines handled badly. The International Morse agreed at Berlin in 1851 removed those and is the version still in use.

The code outlived its machine by a century. The telegraph is a museum piece; Morse is not. It stayed in maritime service until 1999, remains in amateur radio, and is still specified for aviation navigation beacons, which identify themselves in Morse to this day. Its endurance comes from the property in step 3: any channel that can be turned on and off can carry it, and a human ear can pull it out of noise that would defeat a voice transmission entirely.

Where it sits among neighbours in this catalogue: Baudot uses fixed-length codes so a machine can print without judging gaps; Huffman coding computes the provably shortest variable-length code for a specific message rather than for English in general; barcodes apply the same short-and-long idea to space instead of time. Morse's region is the one where a person is the receiver, the channel is poor, and the equipment might be nothing more than a torch.

A note on SOS: it stands for nothing. It was adopted in 1906 because three dots, three dashes, three dots is an unmistakable rhythm, easy to send and hard to confuse — the letters were chosen to fit the pattern, not the other way round.