1872
1874

1873

Western Union contracts with Thomas Edison and Elisha Gray to solve telegraph multiplexing
Thomas Edison Elisha Gray
PDF: Western Union Annual Report 1873
Western Union Annual Report 1873
Photo: Western Union contracts with Thomas Edison and Elisha Gray to solve telegraph multiplexing
Western Union contracts with Thomas Edison and Elisha Gray to solve telegraph multiplexing
Elisha Gray demonstrates his 'harmonic telegraph' to Western Union
Elisha Gray demonstrates his 'harmonic telegraph' to Western Union