The Absolute Magnetic Hut was used in association with, and as a reference point for, observations made in the Magnetograph House. It was located one hundred and seventy feet (52 m) south of Magnetograph House, on a raised rock shelf. The Absolute Magnetic Hut was erected during February 1912, using remnant timber not used in other building efforts.

It was six foot square (1.8 m x 1.8 m) in plan with a skillion roof. It had an Oregon timber frame which was fixed with copper nails and lined with timber boarding. Tar–paper was added internally and fixed with battens for weatherproofing. The structure was anchored to the ground to prevent it from being blown away by wind. The instruments inside the hut were set into the rock and measurements were taken through small sliding doors, without entering the structure.