On this page of our guide to BioShock Infinite you will find the third part of a detailed walkthrough of Chapter 38 - Engineering Deck. The journey to the Captain's Bridge is temporarily free of fighting. Thanks to a careful exploration of the luxury cabins you can find two voxophones.
Make sure to explore Comstock's bedroom on your way to the bridge. The bedroom is located between floors, opposite the stained-glass window. Pick up Voxophone #79 from the bed.
There's also Comstock's study on the same floor. Approach the large desk found in this cabin and collect Voxophone #80 (this is the last recording you'll find in the game).
Go behind the glass-stained window and ask Elizabeth to open a gate leading to the zeppelin's bridge. Use the steering controls found on the bridge when you're ready for the final battle.