Bell's application, filed on February 14, 1876, described a method of transmitting speech electrically. Hours later that same day, Elisha Gray filed a notice describing a similar device, setting off decades of legal disputes over who truly invented the telephone. The U.S. Patent Office ultimately awarded Bell patent number 174,465, one of the most valuable patents in history.
The timing was almost absurdly close. On the morning of February 14, 1876, Alexander Graham Bell's lawyer walked into the U.S. Patent Office in Washington and filed an application titled 'Improvement in Telegraphy.' Later that same day, Elisha Gray, a Chicago-based inventor working for Western Union, filed a caveat, a kind of placeholder notice of an invention not yet finalized, describing a strikingly similar device for transmitting vocal sounds electrically.
Who filed first, and whether Bell's lawyer had improperly viewed Gray's caveat before completing Bell's application, became the subject of bitter dispute and congressional inquiry for years afterward. Bell's own notebooks show he added a crucial detail, a description of a liquid transmitter, in the margin of his patent after the initial filing, a detail suspiciously similar to Gray's design.
Despite the controversy, the Patent Office granted Bell U.S. Patent No. 174,465 on March 7, 1876, just weeks later. It became arguably the single most valuable patent ever issued, the foundation of a communications empire that would grow into AT&T. Gray, largely forgotten by history, spent years contesting the outcome without success.