Illustration: Edward Hughes listens to radio waves The story of radio began when, as long as 1964, a Cambridge University professor, James Clerk Maxwell, completed an amazing work of pure mathematics that dealt with something with which he had...

Before the radio was invented people used diverse ways of communication and signals. Here is a flag signal semaphore chart widely adopted and used in the maritime world in 19th and at the beginning of 20th Century.  Illustration: The story of...