It’s the only example left in Tasmania of a properly designed and built Gunpowder house, first put into use in 1851. The structure was beautifully built by convict labour and is in near perfect condition, except for a damaged front entrance, which can easily be repaired.
The Gunpowder house was designed with all the technical and chemical knowledge of the storage and treatment of gunpowder known in the 1840's. Structurally, it’s a superb example of military architecture. Built of sandstone with a slate roof with brick interior and brick vaulted ceilings. The Domain powder magazine, was first built as a double roofed, solid sandstone building, with "vaulted" inner brick ceilings, by the Royal Engineers in 1850-51 and was capable of storing 1600 whole barrels of powder. In 1857 another totally separate bay was added. It remained as Hobart’s main gunpowder storage until 1970.
To overcome the danger from sparks, the only metals used are copper (doors and grills), bronze and brass. In some areas, the floorboards are pegged with wooden dowel. Ventilation is indirect to prevent sparks from bushfires entering the magazine. Two copper conducting rods called "Franklin Rods", (after their inventor, Dr Benjamin Franklin,) protect the building from lightning strikes. These rods run down to two separate water reservoirs to provide safe earthing, a method that was the subject of the first world-wide patent. The small building in the eastern wall is the old ‘shifting house’ in which casks were opened and gunpowder exchanged.
There was a "gunpowder" jetty associated with the magazine for taking deliveries of gunpowder. The jetty was demolished some time after 1970 and all that remains are the stone abutments at the waters edge beyond the slipways towards Government House.