The Code Gallery

Telecommunications in a world without phones

Telecommunications means sending/receiving information over long distances.

Before the middle of the 19th Century, if you wanted to communicate over long distances, you either sent someone with a message, or you tried to signal to them in some way.

Drums, beacon fires, smoke signals, heliographs could send a message faster than a man could run or ride a horse, but their range was limited, and you had to understand the code that was used.


Claude Chappe, a French engineer, first created semaphore using a network of towers in post-revolutionary France. A message could travel hundreds of kilometers in just a few minutes this way.

Railway signals were developed using the same system of winches and mechanical arms. The semaphore alphabet using flags was developed by the navy, and is still used to signal between ships that need to maintain radio silence.

International Flag alphabet

The international flag alphabet is still used today on ships. As well as the letters A-Z and the numbers 0-9, different combinations of flags have special meanings. For example, the letters AD stand for "I must abandon ship".

 After all, you might be able to talk to the captain of a nearby ship by radio, but that won't help you if you don't speak the same language!

Morse Code

Samuel Morse created morse code specifically to send messages by wire. His system of long and short signals, dots and dashes is still used to communicate by radio or flashlight.

You can encode messages and decode them with the resources included on this site.


Introduction Telegraph Telephone Radio
Television Fax Computers Resources