In 1844 Samuel F.B. Morse sent the encoded message 'What hath God wrought' via electromagnetic impulses along a wire from Washington to Baltimore in America, signalling a communications revolution. Telegraphy was introduced to Australia by Irish Canadian Samuel McGowan, who had trained under Morse. The line was hung from poles along the north bank of the Yarra River, connecting Melbourne and the Harbour Master's office at Williamstown in 1854. By 1857 the electric telegraph had replaced the system of signalling flags on Flagstaff Hill employed to disseminate shipping intelligence. Telegraphic communication was established between Melbourne and Geelong (December 1854), Queenscliff (January 1855), Port Melbourne (July 1855), Ballarat and some central Victorian gold towns (December 1856). In 1858 lines connected Melbourne with Adelaide and Sydney, and in that year around 130 000 telegrams were sent in Victoria.
Although an undersea cable laid in Bass Strait carried the first transmission between Melbourne and Launceston in October 1859, the line failed some months afterwards and was not restored until 1869. The first overseas message was received in Melbourne in 1872. The original Central Telegraph Office was situated at the north-east corner of William and Little Bourke streets, with subsequent services located at the Hall of Commerce in Collins Street, Flinders Street and from 1872 at the General Post Office. The technology provided new employment opportunities for women in the city as telegraph operators but was overtaken as telephone access spread in the 20th century.