After you've entered the new location begin exploring it, finding a lever you need to pull. You'll soon lose consciousness and once again you'll end up in DeWitt's office. In order to continue to open a door leading to a side room.
The only way to return to the bridge is to jump through a hole found in the attic and attach Booker to a maintenance hook. Land to the bridge, go to the other side and then enter Comstock's house by going through an opened gate.