Alexander Graham Bell (1847- 1922) is most well known for inventing the telephone. When he was eleven, Bell invented a machine that could clean wheat. He later said that if he had understood electricity at all, he would have been too discouraged to invent the telephone. Everyone else "knew" it was impossible to send voice signals over a wire. Thomas A. Watson, one of Bell's assistants, was trying to reactivate a telegraph transmitter. Hearing the sound, Bell believed that he could solve the problem of sending a human voice over a wire. He figured out how to transmit a simple current first, and received a patent for that invention on March 7, 1876. Five days later, he transmitted actual speech. Sitting in one room, he spoke into the phone to his assistant in another room, saying the now famous words: "Mr. Watson, come here. I need you." The telephone patent is one of the most valuable patents ever issued.