Gray's telephone (1876) : close, but no cigar...

Timing is everything. Elisha Gray knew that all too well. On February 14, 1876, the day that Alexander Graham Bell applied for a patent for his version of the telephone, Elisha Gray applied for a caveat - a document indicating that he intended to file his own patent claim within three months.

But Gray was a few hours too late - Bell had already filed an actual patent application - and the courts later ruled that this took precedence.

Even so, Gray's claim has its merits - Bell first transmitted the sound of a human voice over a wire, using a liquid transmitter of the microphone type previously developed by Gray and unlike any described in Bell's previous patent applications. He also used an electromagnetic metal-diaphragm receiver of the kind built and used publicly by Gray several months earlier.