Tesla letter: We have a message from another world

In the summer of 1899, whilst alone in his Colorado Springs laboratory working with his magnifying transmitter, the inimitable Nikola Tesla observed a series of unusual rhythmic signals which he described as 'counting codes'. Having just detected cosmic radio signals for the first time, Tesla immediately believed them to be attempted communications from an intelligent life-form on either Venus or Mars, and later said of the experience, 'The feeling is constantly growing on me that I had been the first to hear the greeting of one planet to another'.