The ground floor was used to store pitch, turpentine and lead, and there were offices for the engineers of the Dockyard upstairs. The brick passageway at the entrance divided brick-lined pits used for storing the pitch, which was in barrels. Some original pitch marks may still be seen at the foot of the stairs. The bricks used in the building were brought over from England as ship’s ballast, and it is said that the ballast used on the return trip was mostly rum.
The round pillars on the grounds once supported a large boat house with a sail loft above. The plans of this building may be seen in the museum. The roof was destroyed by earthquake in 1871, and concrete caps were placed on each pillar to prevent erosion.