"Mr Watson - come here!"

Those were the first words transmitted through technology on this day, March 10, 1876. They were spoken by Alexander Graham Bell to his assistant, Thomas A Watson, in the next room.

Bell worked on creating a device that could transmit speech electrically. He and another inventor, Elisha Gray, worked independently on similar devices. Gray created a harmonic telegraph, the transmitter and receiver of which consisted of a set of metallic reeds tuned to different frequencies. An electromagnetic coil was located near each of the reeds.

telephone: Bell’s sketch of a telephone. Photograph. Encyclopædia Britannica Online. Web. 10 Mar. 2015. <http://academic.eb.com/EBchecked/media/120543/Alexander-Graham-Bells-sketch-of-a-telephone>.

The device failed, however, Bell took some of Gray's suggestions and created a kind of "liquid" transmitter design, which was the design that permitted the first transmission of speech, "Mr. Watson - come here - I want to see you." And, thanks to the Library of Congress, we can actually view Bell's lab notebook! 

The first public demonstrations of the telephone followed shortly afterward. 139 years later, the telephone as we know it is almost unrecognizable compared to the one Bell started working with, but the simple fact we can communicate electronically remains the same.