Adelaide's exact place in the world marked in city's west parklands at former observatory site turned into high school
Adelaide's exact latitude (south 34˚ 56) and' longitude (east 138˚ 36') was marked in the 21st century by grey pavers in a courtyard at Adelaide High School on the the city western parklands site of the Adelaide Observatory (at right) where Charles Todd calculated the location in the 19th Century.
Pavers image courtesy archeologist Cameron Hartnell; others coutesy State Library of South Australia
Adelaide’s exact geographical location – latitude: south 34˚ 56' longitude: east 138˚ 36' – also deciding its time zone, was marked in the 21st Century by grey pavers in an Adelaide High School extension courtyard.
The school (as Adelaide Boys High) was built in the 1950s on the site of the Adelaide Observatory, that, from 1860, had been in the city west parklands between the ends of Currie and Waymouth streets. It also was the family home of Charles Todd, South Australia’s superintendent of telegraphs, government astronomer, postmaster general and meteorologist.
The Adelaide Observatory complex, completed in 1876, had refracting and transit telescopes, a time service and a seismograph. Todd was able to do geodetic surveys and observe comets, planetary satellites and other astronomical phenomena. With no Australian bureau of meteorology before federation in 1901, the West Terrace observatory became the hub for meteorological observation stations that reported daily using the telegraph system pioneered by Todd. He was basically running the South Australian weather bureau from this site.
As astronomical observer, Todd also was responsible for taking the measurements to maintain Adelaide’s local time standard. The Adelaide meridian – the north-south line where the sun was directly overhead at noon – ran through the observatory (the position later indicated by the grey pavers in Adelaide High School courtyard).
When the world adopted standard time measured from Greenwich, London, as the “prime meridian” in the 1890s, Australia was spanned by three one-hour time zones. Todd, perhaps anticipating federation, proposed that Australia, as one continent, adopt one time zone based on the 135th meridian in South Australia that was nine hours east or ahead of Greenwich, London. He argued this would be a “very great convenience” for people using the telegraph for “communications of an urgent commercial nature to and from all the commercial centres of the world”.
But the majority view was to adopt three one-hour zones and the standard time acts were passed in the Australian colonies. Adelaide adopted central standard time on February1, 1895, that involved putting the clocks back 14 minutes and 20 seconds at midnight on January 31. The 135th meridian ran through Elliston on Eyre Peninsula but Adelaide was a few degrees ahead at 138.6 – so the need to put clocks back. The observed sunrise/sunset times changed by four minutes for every degree of longitude from Adelaide: plus four minutes for Whyalla, plus 20 minutes for Ceduna, minus eight minutes for Mount Gambier.
The eastern colonies adopted the 150th meridian that ran through the Blue Mountains so Sydney only had to alter its clocks by five minutes. Because of its businesses being unable to manage the one-hour time difference with the eastern colonies (particular Melbourne), South Australia’s parliament was persuaded to create the anomaly with an act for all clocks in South Australia on May 1, 1899, to be put forward half an hour, becoming in line local time in Warrnambool, Victoria.
