The doorway is cased by a Tuscan prostyle porch in ashlar limestone with block parapet and projecting cornice mould set over modillion brackets. The frieze is decorated by triglyths separated by unadorned metopes. The only decoration of the architrave is the guttae that give emphasis to the triglyphs above. A pair of doors with small pane glazing above the lock rail and timber panels below close the entrance. The windows are all small pane sliding sashes each with a dressed limestone cill, lintel and stepped dressings to the jambs.
Chimneys crown all four gables.
Between the pitches of the roofs is a wide platform that has been used to mount various instruments. All four corners have stepped fielded quoins. The main feature of the south face is the circular telescope tower which bears the same inscription as the medal. Approximately two thirds of the bulk of the tower projects beyond the body of the building and the observation room at the top creates an attic storey. The whole feature is capped by a hemispherical, copper-clad dome.