• Find the key. There are three locations for this key: Markarth Understone Keep, Septimus Signus' Outpost, and Reachwind Eyrie.
• Find the key and bauble plans in the Mathematicians' Quarters and find the Calculation Tetradecagon in the Calculatory.
• Use the key to find the Arithmetic Puzzle Cube in the Calculatory.
• Place the Calculation Tetradecagon on the Dwarven Mechanism in the Stellar Fulcrum.
• Use the new key to enter the Vault of Secunda.