Double Magnetic Indicator

This double-needle magnetic indicator telegraph instrument patented and manufactured by William Thomas Henley (1813 – 1882), who was based in London, England. W. T. Henley was an electrical engineer and pioneer in the manufacture of telegraph cables. He undertook work for a number of people, including Charles Wheatstone and William Henry Fox Talbot. This instrument is based on the ABC system designed by Charles Wheatstone in 1840, where the letters of the alphabet were arranged around a clock-face, and the signal caused a needle to indicate the letter. This early system required the receiver to be present in real time to record the message. Australia was a relatively early adopter of telegraph technology from the mid-1850s, despite its low population densities and the difficult conditions sometimes encountered in laying lines. The first line was completed in South Australia in November 1855, and during the same month Charles Todd arrived in the Colony as the Superintendent of Telegraphs. The social impact of the telegraph in Australia was great, with most demand for use coming from Government, business and newspapers. In 1856, the electric telegraph line was extended from Port Adelaide to Semaphore. Instruments using this system was not widely used but was in operation on the Adelaide-Semaphore line in South Australia in the 1850s before being superseded by Morse instruments. Telegraph services declined in usage following the end of World War II due to the increase in popularity of the telephone.

This item was donated by the Postmaster General in 1912 to the Art Gallery of South Australia. It was later transferred to the History Trust of South Australia. Following the federation of Australia in 1901, the Postmaster-General's Department was established to administer postal and telegraphic services on a national basis. This object is part of the Historical Relics collection, which includes a number of objects relating to the telegraph in South Australia.