In 1829, Governor Sir George Arthur ordered the construction of a heated wall to protect frost-tender plants and extend growing periods of fruit trees on the boundary of the Colonial Gardens. Styled on the heated walls that were popular at the time in English gardens, it had internal channels built into the thick brickwork.
In theory, coal-fired furnaces would send hot air through the channels, radiating heat through the wall's thick brick and stone surfaces. However, this convict-built wall was only heated on a few occasions over the years as it was soon realised that this functionality was not needed. As opposed to the harsh winters of England, the milder climate of Van Diemen's Land (Tasmania), meant fruit trees flourished without the need for artificial heat. Also, the main face of the wall has a mostly northerly aspect which gets full sun throughout the year. Warmed by the sun during the day, the large amount of stone and brick in the wall acts as a heat store, re-radiating heat through much of the night.
Although not useful in the way intended, the wall did prove effective in keeping the public out. It also supported a glasshouse which enabled Davidson to grow exotic fruit, specifically some of Australia's first pineapples.
The wall had developed a noticeable lean to the east before buttresses were added. The sandstone facing is standing up quite well to weathering, but the bricks are beginning to show signs of deterioration, partly due to the high salt content in the local clay.
This is the only wall of its type in the Southern Hemisphere and one of only a handful around the world.